PRIHARDI Kahar | ![]() |
プリハルディ カハル | |
大学院工学研究科 応用化学専攻 | |
准教授 | |
農芸化学関係 |
2004年 International Symposium on Biological Polyesters (ISBP), The Prominent Poster Award, Effective Production and Kinetic Characteristic of Ultra-high-molecular-weight of PHB in Recombinant Escherichia coli
中華人民共和国国際学会・会議・シンポジウム等の賞
Each year, the palm oil industry generates a significant amount of biomass residue and effluent waste; both have been identified as significant sources of greenhouse gas (GHG) emissions. This issue poses a severe environmental challenge for the industry due to the possibility of long-term negative effects on human well-being. The palm-oil industry must invest significantly in the technology that is required to resolve these issues and to increase the industry's sustainability. However, current technologies for converting wastes such as lignocellulosic components and effluents into biochemical products are insufficient for optimal utilization. This review discusses the geographical availability of palm-oil biomass, its current utilization routes, and then recommends the development of technology for converting palm-oil biomass into value-added products through an integrated biorefinery strategy. Additionally, this review summarizes the palm oil industry's contribution to achieving sustainable development goals (SDGs) through a circular bioeconomy concept.
2021年11月02日, Bioresource technology, 126266 - 126266, 英語, 国際誌[査読有り]
研究論文(学術雑誌)
Lignocellulosic biomass has great potential as an inedible feedstock for bioplastic synthesis, although its use is still limited compared to current edible feedstocks of glucose and starch. This review focuses on recent advances in the production of biopolymers and biomonomers from lignocellulosic feedstocks with downstream processing and chemical polymer syntheses. In microbial production, four routes composed of existing poly (lactic acid) and polyhydroxyalkanoates (PHAs) and the emerging biomonomers of itaconic acid and aromatic compounds were presented to review present challenges and future perspectives, focusing on the use of lignocellulosic feedstocks. Recently, advances in purification technologies decreased the number of processes and their environmental burden. Additionally, the unique structures and high-performance of emerging lignocellulose-based bioplastics have expanded the possibilities for the use of bioplastics. The sequence of processes provides insight into the emerging technologies that are needed for the practical use of bioplastics made from lignocellulosic biomass.
2021年10月22日, Bioresource technology, 126165 - 126165, 英語, 国際誌[査読有り]
研究論文(学術雑誌)
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研究論文(学術雑誌)
Biorefinery has been suggested to provide relevant substitutes to a number of fossil products. Feedstocks and conversion technologies have, however, been the bottleneck to the realization of this concept. Herein, feedstocks and bioconversion technologies under biorefinery have been reviewed. Over the last decade, research has shown possibilities of generating tens of new products but only few industrial implementations. This is partly associated with low production yields and poor cost-competitiveness. This review addresses the technical barriers associated with the conversion of emerging feedstocks into chemicals and bioenergy platforms and summarizes the developed biotechnological approaches including advances in metabolic engineering. This summary further suggests possible future advances that would expand the portfolio of biorefinery and speed up the realization of biofuels and biochemicals.
2019年06月, Biotechnology Journal, 14 (6), 1800494, 英語, 国際誌[査読有り]
研究論文(学術雑誌)
A novel strategy for the low-cost, high-yield co-production of xylose and xylooligosaccharides together with no xylose inhibition was developed using a novel heterologous expression of XYN10Ks_480 endo-1,4-β-xylanase with a ricin-type β-trefoil type of domain and XYN11Ks_480 endo-1,4-β-xylanase with a CBM 2 superfamily from the Kitasatospora sp in an actinomycetes expression system. Xylose is the main building block for hemicellulose xylan. Our findings demonstrated high levels of expression and catalytic activity for XYN10Ks_480 during hydrolysis of the extracted xylan of bagasse, and three types of xylan-based substrates were used to produce xylose and xylooligosaccharides. However, hydrolysis by XYN11Ks_480 produced xylooligosaccharides without xylose formation. This study demonstrated how integrating sodium hypochlorite-extracted xylan and enzymatic hydrolysis could provide an alternative strategy for the generation of XOS from lignocellulosic material.
2019年01月, Bioresource technology, 272, 315 - 325, 英語, 国際誌[査読有り]
研究論文(学術雑誌)
The ability of oleaginous yeast Lipomyces starkeyi to efficiently produce lipids when cultivated on sap extracted from felled oil palm trunk (OPT) as a novel inexpensive renewable carbon source was evaluated. OPT sap was found to contain approximately 98 g/L glucose and 32 g/L fructose. Batch fermentations were performed using three different OPT sap medium conditions: regular sap, enriched sap, and enriched sap at pH 5.0. Under all sap medium conditions, the cell biomass and lipid production achieved were approximately 30 g/L and 60% (w/w), respectively. L. starkeyi tolerated acidified medium (initial pH ≈ 3) and produced considerable amounts of ethanol as well as xylitol as by-products. The fatty acid profile of L. starkeyi was remarkably similar to that of palm oil, one of the most common vegetable oil feedstock used in biodiesel production with oleic acid as the major fatty acid followed by palmitic, stearic and linoleic acids.
2019年01月, Journal of bioscience and bioengineering, 127 (6), 726 - 731, 英語, 国内誌[査読有り]
研究論文(学術雑誌)
A two-stage selection process was applied to eight oleaginous yeast strains from the Lipomyces genera. In the primary selection stage, a nitrogen-limited mineral medium (-NMM) that contained a mixture of glucose and xylose as a carbon source was used to evaluate the lipid-accumulating abilities of the yeast strains. The strains L. doorenjongii, L. orientalis, and L. starkeyi were selected as the potential strains in the primary selection. These three strains exhibited a remarkable ability to simultaneously assimilate glucose and xylose and achieved a cell biomass of more than 30 g/L. The values for lipid content in the selected strains were 57.89 ± 1.92, 56.38 ± 1.93, and 77.14 ± 1.55% for L. doorenjongii, L. orientalis, and L. starkeyi, respectively. In the secondary selection, when the -NMM medium contained an inhibitory chemical compound (ICC), the selected strains showed a different tolerance level against each of the typical inhibitor compounds. However, L. starkeyi accumulated the highest lipid content and yield at 68.24 ± 2.48% and 0.19 ± 0.00 (w/w), respectively. L. starkeyi accumulated high levels of intracellular lipid and tolerated the ICC. The composition of fatty acid methyl esters (FAMEs) was unaltered by the presence of ICC and the major FAMEs consisted of oleic, palmitic, stearic, palmitoleic and linoleic acids.
Elsevier B.V., 2018年09月15日, Biochemical Engineering Journal, 137, 182 - 191, 英語[査読有り]
研究論文(学術雑誌)
The aim of this study was to construct a cost-effective method for repeated bioethanol production using membrane (ultrafiltration permeation and nanofiltration concentration)-concentrated sweet sorghum juice by using flocculent Saccharomyces cerevisiae F118 strain. With low initial dry cell concentrations at around 0.28-0.35 g L-1, the S. cerevisiae F118 strain provided an ethanol titer of 86.19 ± 1.15 g L-1 (theoretical ethanol yield of 70.77%), which was higher than the non-flocculent S. cerevisiae BY4741 strain at 33.92 ± 0.99 g L-1 after 24 h fermentation. This result was correlated with higher gene expressions of the sucrose-hydrolysing enzyme invertase, sugar phosphorylation, and pyruvate-to-ethanol pathways in the F118 strain compared with the BY4741 strain. Sequential fed-batch fermentation was conducted, and the F118 strain was easily separated from the fermentation broth via the formation of flocs and sediment. After the 5th cycle of fermentation with the F118 strain, the ethanol concentration reached 100.37 g L-1.
2018年07月, Bioresource technology, 265, 542 - 547, 英語, 国際誌[査読有り]
研究論文(学術雑誌)
Actinobacteria plays a key role in the cycling of organic matter in soils. They secret biomass-degrading enzymes that allow it to produce the unique metabolites that originate in plant biomass. Although past studies have focused on these unique metabolites, a large-scale screening of Actinobacteria is yet to be reported to focus on their biomass-degrading ability. In the present study, a rapid and simple method is constructed for a large-scale screening, and the novel resources that form the plant biomass-degrading enzyme cocktail are identified from 850 isolates of Actinobacteria. As a result, Nonomuraea fastidiosa secretes a biomass degrading enzyme cocktail with the highest enzyme titer, although cellulase activities are lower than a commercially available enzyme. So the rich accessory enzymes are suggested to contribute to the high enzyme titer for a pretreated bagasse with a synergistic effect. Additionally, an optimized cultivation method of biomass induction caused to produce the improved enzyme cocktail indicated strong enzyme titers and a strong synergistic effect. Therefore, the novel enzyme cocktails are selected via the optimized method for large-scale screening, and then the enzyme cocktail can be improved via the optimized production with biomass-induction.
2018年07月, Biotechnology journal, 14 (3), e1700744, 英語, 国際誌[査読有り]
研究論文(学術雑誌)
Oleaginous microbes can convert substrates such as carbon dioxide, sugars, and organic acids to single-cell oils (SCOs). Among the oleaginous microorganisms, Lipomyces starkeyi is a particularly well-suited host given its impressive native abilities, including the capability to utilize a wide variety of carbon sources. In this work, the potential of L. starkeyi NBRC10381 to produce SCOs in a synthetically nitrogen-limited mineral medium (-NMM) was investigated by differing the inoculum size using glucose and/or xylose as a carbon source. Fermentation using glucose and xylose as mixed carbon sources generated the highest production of biomass at 40.8 g/L, and achieved a lipid content of 84.9% (w/w). When either glucose or xylose was used separately, the totals for achieved lipid content were 79.6% (w/w) and 85.1% (w/w), respectively. However, biomass production was higher for glucose than for xylose (30.3 vs. 28.7 g/L, respectively). This study describes the first simultaneous achievement of higher levels of cell mass and lipid production using glucose and/or xylose as the carbon sources in different inoculum sizes.
Elsevier B.V., 2018年06月01日, Journal of Bioscience and Bioengineering, 125 (6), 695 - 702, 英語[査読有り]
研究論文(学術雑誌)
The addition of enzymes that are capable of degrading hemicellulose has a potential to reduce the need for commercial enzymes during biomass hydrolysis in the production of fermentable sugars. In this study, a high xylanase producing actinomycete strain (Kitasatospora sp. ID06-480) and the first ethyl ferulate producing actinomycete strain (Nonomuraea sp. ID06-094) were selected from 797 rare actinomycetes, respectively, which were isolated in Indonesia. The addition (30%, v/v) of a crude enzyme supernatant from the selected strains in sugarcane bagasse hydrolysis with low-level loading (1 FPU/g-biomass) of Cellic® CTec2 enhanced both the released amount of glucose and reducing sugars. When the reaction with Ctec2 was combined with crude enzymes containing either xylanase or feruloyl esterase, high conversion yield of glucose from cellulose at 60.5% could be achieved after 72 h-saccharification.
Japan Society for Bioscience Biotechnology and Agrochemistry, 2018年, Bioscience, Biotechnology and Biochemistry, 82 (5), 904 - 915, 英語[査読有り]
研究論文(学術雑誌)
This work aims to produce glutathione directly from mannan-based bioresources using engineered Saccharomyces cerevisiae. Mannan proved to be a valuable carbon source for glutathione production by this organism. Mannan-hydrolyzing S. cerevisiae was developed by heterologous expression of mannanase/ mannosidase on its cell surface. This strain efficiently produced glutathione from mannose polysaccharide, beta-1,4-mannan. Furthermore, it produced glutathione from locust bean gum (LBG), a highly dense and inexpensive mannan-based bioresource, as sole carbon source. Glutathione productivity from LBG was enhanced by engineering the glutathione metabolism of mannan-hydrolyzing S. cerevisiae. Expression of extracellular mannanase/mannosidase protein combined with intracellular metabolic engineering is potentially applicable to the efficient, environmentally friendly bioproduction of targeted products from mannan-based bioresources. (C) 2017 Elsevier Ltd. All rights reserved.
ELSEVIER SCI LTD, 2017年12月, BIORESOURCE TECHNOLOGY, 245 (Pt B), 1400 - 1406, 英語[査読有り]
研究論文(学術雑誌)
This study provides insight observation based on the gene expression and the metabolomic analysis of the natural robust yeast Saccharomyces cerevisiae NBRC849 during the fermentation in the medium containing inhibitory chemical complexes (ICC) at different concentrations. The tolerance mechanisms involved in the strain might have existed through the upregulation of genes involved in NAD(H)/NADP (H) cofactors generations (ALD6, ZWF1, GND1), membrane robustness for efflux pump (YOR1, PDR5, TPO3) and cation/polyamine transport (TPO3). The alteration of metabolic flux to the shikimic pathway was also found in this strain, resulted in the enhanced formation of aromatic amino acid required for cell survival. Enhanced expression of these genes as well as the increase of metabolic flux to shikimic pathway were suggested to result in the robustness of non-flocculating S. cerevisiae haploid strain. (C) 2017 Elsevier Ltd. All rights reserved.
ELSEVIER SCI LTD, 2017年12月, BIORESOURCE TECHNOLOGY, 245 (Pt B), 1436 - 1446, 英語[査読有り]
研究論文(学術雑誌)
Caffeic acid (3,4-dihydroxycinnamic acid) serves as a building block for thermoplastics and a precursor for biologically active compounds and was recently produced from glucose by microbial fermentation. To produce caffeic acid from inedible cellulose, separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) reactions were compared using kraft pulp as lignocellulosic feedstock. Here, a tyrosine-overproducing Escherichia coli strain was metabolically engineered to produce caffeic acid from glucose by introducing the genes encoding a 4-hydroxyphenyllactate 3-hydroxylase (hpaBC) from Pseudomonas aeruginosa and tyrosine ammonia lyase (fevV) from Streptomyces sp. WK-5344. Using the resulting recombinant strain, the maximum yield of caffeic acid in SSF (233 mg/L) far exceeded that by SHF (37.9 mg/L). In the SSF with low cellulase loads (ae<currency>2.5 filter paper unit/g glucan), caffeic acid production was markedly increased, while almost no glucose accumulation was detected, indicating that the E. coli cells experienced glucose limitation in this culture condition. Caffeic acid yield was also negatively correlated with the glucose concentration in the fermentation medium. In SHF, the formation of by-product acetate and the accumulation of potential fermentation inhibitors increased significantly with kraft pulp hydrolysate than filter paper hydrolysate. The combination of these inhibitors had synergistic effects on caffeic acid fermentation at low concentrations. With lower loads of cellulase in SSF, less potential fermentation inhibitors (furfural, 5-hydroxymethyfurfural, and 4-hydroxylbenzoic acid) accumulated in the medium. These observations suggest that glucose limitation in SSF is crucial for improving caffeic acid yield, owing to reduced by-product formation and fermentation inhibitor accumulation.
SPRINGER, 2017年07月, APPLIED MICROBIOLOGY AND BIOTECHNOLOGY, 101 (13), 5279 - 5290, 英語[査読有り]
研究論文(学術雑誌)
Mannan endo-1,4-beta-mannosidase(commonly known as beta-mannanase) catalyzes a random cleavage of the beta-D-1,4mannopyranosyl linkage in mannan polymers. The enzyme has been utilized in biofuel production from lignocellulose biomass, as well as in production of mannooligosaccharides (MOS) for applications in feed and food industries. We aimed to obtain a beta-mannanase, for such mannan polymer utilization, from actinomycetes strains isolated in Indonesia. Strains exhibiting high mannanase activity were screened, and one strain belonging to the genus Kitasatospora was selected. We obtained a beta-mannanase from this strain, and an amino acid sequence of this Kitasatospora beta-mannanase showed a 58-71% similarity with the amino acid sequences of Streptomyces beta-mannanases. The Kitasatospora beta-mannanase showed a significant level of activity (944 U/mg) against locust bean gum (0.5% w/v) and a potential for oligosaccharide production from various mannan polymers. The beta-mannanase might be beneficial particularly in the enzymatic production of MOS for applications of mannan utilization.
BIOMED CENTRAL LTD, 2017年05月, AMB Express, 7 (1), 100, 英語[査読有り]
研究論文(学術雑誌)
Chinese hamster ovary (CHO) cells are the primary host used for biopharmaceutical protein production. The engineering of CHO cells to produce higher amounts of biopharmaceuticals has been highly dependent on empirical approaches, but recent high-throughput "omics" methods are changing the situation in a rational manner. Omics data analyses using gene expression or metabolite profiling make it possible to identify key genes and metabolites in antibody production. Systematic omics approaches using different types of time-series data are expected to further enhance understanding of cellular behaviours and molecular networks for rational design of CHO cells. This study developed a systematic method for obtaining and analysing time-dependent intracellular and extracellular metabolite profiles, RNA-seq data (enzymatic mRNA levels) and cell counts from CHO cell cultures to capture an overall view of the CHO central metabolic pathway (CMP). We then calculated correlation coefficients among all the profiles and visualised the whole CMP by heatmap analysis and metabolic pathway mapping, to classify genes and metabolites together. This approach provides an efficient platform to identify key genes and metabolites in CHO cell culture.
NATURE PUBLISHING GROUP, 2017年03月, SCIENTIFIC REPORTS, 7, 43518, 英語[査読有り]
研究論文(学術雑誌)
Background: Mannans represent the largest hemicellulosic fraction in softwoods and also serve as carbohydrate stores in various plants. However, the utilization of mannans as sustainable resources has been less advanced in sustainable biofuel development. Based on a yeast cell surface-display technology that enables the immobilization of multiple enzymes on the yeast cell walls, we constructed a recombinant Saccharomyces cerevisiae strain that co-displays beta-mannanase and beta-mannosidase; this strain is expected to facilitate ethanol fermentation using mannan as a biomass source. Results: Parental yeast S. cerevisiae assimilated mannose and glucose as monomeric sugars, producing ethanol from mannose. We constructed yeast strains that express tethered beta-mannanase and beta-mannosidase; co-display of the two enzymes on the cell surface was confirmed by immunofluorescence staining and enzyme activity assays. The constructed yeast cells successfully hydrolyzed 1,4-beta-D-mannan and produced ethanol by assimilating the resulting mannose without external addition of enzymes. Furthermore, the constructed strain produced ethanol from 1,4-beta-D-mannan continually during the third batch of repeated fermentation. Additionally, the constructed strain produced ethanol from ivory nut mannan; ethanol yield was improved by NaOH pretreatment of the substrate. Conclusions: We successfully displayed beta-mannanase and beta-mannosidase on the yeast cell surface. Our results clearly demonstrate the utility of the strain co-displaying beta-mannanase and beta-mannosidase for ethanol fermentation from mannan biomass. Thus, co-tethering beta-mannanase and beta-mannosidase on the yeast cell surface provides a powerful platform technology for yeast fermentation toward the production of bioethanol and other biochemicals from lignocellulosic materials containing mannan components.
BIOMED CENTRAL LTD, 2016年09月, Biotechnology for biofuels, 9 (1), 188, 英語[査読有り]
研究論文(学術雑誌)
Dilute acid-pretreated sorghum bagasse, which was predominantly composed of glucan (59%) and xylose (7.2%), was used as a lignocellulosic feedstock for D-phenyllactic acid (PhLA) production by a recombinant Escherichia coli strain expressing phenylpyruvate reductase from Wickerhamia fluorescens. During fermentation with enzymatic hydrolysate of sorghum bagasse as a carbon source, the PhLA yield was reduced by 35% compared to filter paper hydrolysate, and metabolomics analysis revealed that NAD(P)H regeneration and intracellular levels of erythrose-4-phosphate and phosphoenolpyruvate for PhLA biosynthesis markedly reduced. Compared to separate hydrolysis and fermentation (SHF) with sorghum bagasse hydrolysate, simultaneous saccharification and fermentation (SSF) of sorghum bagasse under glucose limitation conditions yielded 4.8-fold more PhLA with less accumulation of eluted components, including p-coumaric acid and aldehydes, which inhibited PhLA fermentation. These results suggest that gradual enzymatic hydrolysis during SSF enhances PhLA production under glucose limitation and reduces the accumulation of fermentation inhibitors, collectively leading to increased PhLA yield. (c) 2015 Elsevier Ltd. All rights reserved.
ELSEVIER SCI LTD, 2015年04月, BIORESOURCE TECHNOLOGY, 182, 169 - 178, 英語[査読有り]
研究論文(学術雑誌)
Bioethanol production from lignocellulosic biomass, in particular xylose, is currently of great concern, given the abundance of this sugar in the world, because Saccharomyces cerevisiae, which is widely used for bioethanol production, is unable to naturally ferment xylose. The aim of this study was to obtain a novel yeast capable of stably producing ethanol from biomass contain
Springer, 2014年, Sustainable Chemical Processes, 2 (17), 1 - 12, 英語[査読有り]
研究論文(学術雑誌)
The multiple effects of pretreatments by chemical delignification using acidified sodium chlorite (ASC) and swelling using sodium bicarbonate (SB) for enzymatic saccharification of rice straw in bioethanol production have been investigated in this study. The treatment with the combination of ASC three times (3 x ASC) first and SB later resulted in the significant reduction in Mason lignin content up to 90% (wt./wt.). By the saccharification of the pretreated rice straw with cellulase enzymes, it was confirmed that SB treatment was an important step in the pretreatment process not only to disintegrate the cellulose structure but also to facilitate the amorphization of the crystalline cellulose as well as the extended removal of integrated lignin. Furthermore, FTIR analyses revealed that the crystal type of cellulose appeared to be changed from type I to type II by SB treatment, thereby increasing the cellulose surface area and making it more accessible to the cellulase enzyme. Conversion rate to sugar was remarkably increased when 3x ASC + SB treatments were applied to untreated rice straw, even though the saccharification of the treated rice straw was performed at a low enzyme loading (1/100, wt.-enzymes/wt.-substrate). Conclusively, rice straw could be saccharified at high yield in short time at low cellulase loading, enables the enzymatic saccharification to be more feasible for practical bioethanol production using rice straw as a substrate. (C) 2013, The Society for Biotechnology, Japan. All rights reserved.
SOC BIOSCIENCE BIOENGINEERING JAPAN, 2013年12月, JOURNAL OF BIOSCIENCE AND BIOENGINEERING, 116 (6), 725 - 733, 英語[査読有り]
研究論文(学術雑誌)
Chemical mutation of Saccharomyces cerevisiae using ethyl methane sulfonate was performed to enhance its ability of xylose uptake for ethanol production from lignocellulose under microaerobic condition. Among the appeared mutants, the mutant no. 2 (M2) strain screened using inhibitory effects of 2-deoxyglucose (DOG) showed more than 4-fold high ability in xylose uptake compared with the wild type strain, under the presence of glucose. The catabolite repression by glucose was sufficiently reduced in M2 strain due to its tolerance to the high concentration of DOG (0.5%, wt./vol.). Metabolomic analyses of various sugars in the cell revealed that some of xylose was reduced to xylitol in M2 cell, providing the concentration gradient of xylose and more uptake of xylose. Xylulose-5-phosphate was significantly detected in the crude cell extract from M2 strain, indicating higher metabolic activity in pentose phosphate pathway. This was also confirmed by in vitro analyses of key enzymes involved in glucose and xylose metabolism, such as hexokinase, glucose-6-phosphate dehydrogenase and xylose reductase. Glucose uptake was moderately suppressed in the presence of trehalose-6-phosphate inhibiting the activation of hexokinase, resulting in more uptake of xylose through hexose transport system. To our knowledge, this study is the first report verifying that the mutation technique successfully enhances the xylose uptake by S. cerevisiae, particularly under the presence of glucose. (C) 2010, The Society for Biotechnology, Japan. All rights reserved.
SOC BIOSCIENCE BIOENGINEERING JAPAN, 2011年05月, JOURNAL OF BIOSCIENCE AND BIOENGINEERING, 111 (5), 557 - 563, 英語[査読有り]
研究論文(学術雑誌)
A local thermophilic microorganism namely DMS-3 has been identified as thermostable alkaline lipase producing isolate. The bacterium was isolated from Domas hot spring, Tangkuban Perahu Mount, West Java. Based on gram staining test and Scanning Electron Microscopy, the microorganism showed a rod shape and a gram positive bacterium. The isolated showed maximum expression of lipase at pH 9 and 70°C. The lipase produced by DMS-3 isolate was purified using column chromatography of DEAE sepharose fast flow and Sephacryl S-200. Following Sephacryl separation the enzyme still showed specific activity at 54 times higher compared to that the wild type, with yield was about 4.89%. Polyacryamide gel electrophoresis combining with zymogram analysis showed that there were 4 bands of protein exhibiting lipase activity. Further analysis by eluting of each band showed that the first, second, and third band revealed few bands similar of each other on denatured SDS-PAGE. Meanwhile the fourth band only showed single band. The data suggested that DMS-3 isolated expressed more than one type of lipases.
2010年12月01日, Biosciences Biotechnology Research Asia, 7, 617 - 622This study aimed to investigate the factors affecting molecular weight of poly[(R)-3-hydroxybutyrate] [P(3HB)] when polyhydroxyalkanoate (PHA) synthase (PhaRC(Bsp)) from Bacillus sp. INT005 was used for P(3HB) synthesis in Escherichia coli JM109. It was found that the molecular weight of P(3HB) decreased with time in mid- and late-phase of culture and was strongly affected by culture temperature. At 37 degrees C culture temperature, the molecular weight of P(3HB) rapidly decreased from 4.4 x 10(5) to 4.8 x 10(4) with culture time, whereas it was almost unchanged at 25 degrees C. Kinetic analysis suggested that the decrease in molecular weight of P(3HB) was due to random scission of the polymer chain. The decrease in molecular weight of P(3HB) was not observed when PHA synthases other than PhaRC(Bsp) were expressed. This study sheds light on the unique behaviour in molecular weight change of P(3HB) that is synthesized by E. coli expressing PhaRCB(sp). (C) 2010 Elsevier Ltd. All rights reserved.
ELSEVIER SCI LTD, 2010年12月, POLYMER DEGRADATION AND STABILITY, 95 (12), 2250 - 2254, 英語研究論文(学術雑誌)
In this study, the effect and the optimum pretreatment condition of corncobs using low strength of H(2)SO(4) were investigated, in which H(2)SO(4) was used to improve the enzymatic digestibility of corncobs for saccharification without degradation of sugars released. The optimum pretreatment condition was found to be the addition of 0.5% (vol./vol.) H(2)SO(4) and autoclaving at 122 degrees C for 20 min. Under this condition, the structural integrity of corncob was altered to make cellulose microfibrils more accessible for cellulase enzymes, and the enzymatic digestion of corncobs could be significantly enhanced. A high yield of sugar, 80% (wt./wt.), could be obtained at a low enzyme dosage of 0.024 g enzymes/g cobs, when pretreated. As a result, the ethanol production was obviously improved by the pretreatment, i.e., the ethanol yield of 77% (wt./wt.) was obtained within 36 h in the SSF fermentation using Saccharomyces cerevisiae NBRC2114. (C) 2010, The Society for Biotechnology, Japan. All rights reserved.
SOC BIOSCIENCE BIOENGINEERING JAPAN, 2010年10月, JOURNAL OF BIOSCIENCE AND BIOENGINEERING, 110 (4), 453 - 458, 英語[査読有り]
研究論文(学術雑誌)
Polyhydroxyalkanoate (PHA) synthase (PhaC) from Wautersia eutropha was expressed in a wide range of production level in Escherichia coli XL1-Blue cells and its effects on PhaC activity, poly[(R)-3-hydroxybutyrate] [P(3HB)] production and its molecular weights were investigated. The production level of PhaC was controlled by both amount of chemical inducer (IPTG) added into the medium and use of different copy number of plasmids. In a flask experiment, as increasing PhaC production level in the cells, the PhaC activity also increased in the range of low PhaC concentration. However, PhaC activity did not further increase in the range of high PhaC concentration, probably due to formation of inclusion body in the cells. The molecular weight of P(3HB) was found to decrease with increasing PhaC activity. This trend was also verified in high cell density cultivation using 10-l jar fermentor. Furthermore, we demonstrated that use of low copy number plasmid and appropriate induction of PhaC expression were effective in achieving both high productivity and high molecular weight of P(3HB).
2006年10月19日, Polymer Preprints, Japan, 55, 2204Polyhydroxyalkanoate (PHA) synthase (PhaC) from Wautersia eutropha was expressed in a wide range of production level in Escherichia coli XL1-Blue cells and its effects on PhaC activity, poly [(R)-3-hydroxybutyrate] [P(3HB)] production and its molecular weights were investigated. The production level of PhaC was controlled both by the amount of chemical inducer (isopropyl-beta-D-thiogalactopyranoside, IPTG) added into the medium and the use of different copy number of plasmids. In a flask experiment, as PhaC production level in the cells increased, the PhaC activity also increased in the range of low PhaC concentration. However, PhaC activity did not further increase in the range of high PhaC concentration, probably due to the formation of inclusion body in the cells. The molecular weight of P(3HB) was found to decrease with increasing PhaC activity. This trend was also verified in high cell density cultivation using 10-1 jar fermentor. Furthermore, we demonstrated that the use of low copy number plasmid and appropriate induction of PhaC expression were effective in achieving both high productivity and high molecular weight of P(3HB). (c) 2006 Elsevier Ltd. All rights reserved.
ELSEVIER SCI LTD, 2006年08月, POLYMER DEGRADATION AND STABILITY, 91 (8), 1645 - 1650, 英語研究論文(学術雑誌)
This study investigated the relationship of growth conditions, host strains and molecular weights of poly[(R)-3-hydroxybutyrate] [P(3HB)] synthesized by genetically engineered Escherichia coli. Various PHA synthases belonging to types I-IV enzymes were expressed in E. coli JM109 under the same experimental conditions, and the molecular weights of the polymers were characterized by gel permeation chromatography. The results demonstrate that P(3HB) polymers have varied molecular weights and polydispersities dependent on the characteristics of the individual PHA synthase employed. P(3HB) with high number-average molecular weights (Mn) [(1.5-4.0) X 10(6)] and narrow polydispersities (1.6-1.8) were synthesized by PHA synthases from Ralstonia eutropha (type 1), Delftia acidovorans (type 1) and Allochromatium vinosum (type 111). Contrary to these, P(3HB) with relatively low M-n [(0.17-0.79) X 10(6)] and broad polydispersities (2.2-9.0) were synthesized by PHA synthases from Aeromonas caviae (type I), Pseudomonas sp. 61-3 (type II) and Bacillus sp. INT005 (type IV). Furthermore, the molecular weights of P(3HB) synthesized under various culture conditions, in various hosts of E. coli and by mutants of PHA synthase were characterized. It was found that, in addition to culture pH [Kusaka et al. Appl Microbiol Biotechnol 1997;47:140], other variances such as culture temperature, host strain and use of mutants are effective in changing polymer molecular weight. (c) 2005 Elsevier Ltd. All rights reserved.
ELSEVIER SCI LTD, 2006年05月, POLYMER DEGRADATION AND STABILITY, 91 (5), 1138 - 1146, 英語研究論文(学術雑誌)
An inducible and highly effective production of ultra-high-molecular-weight poly[(R)-3-hydroxybutyrate] [UHMW-P(3HB)] in recombinant Escherichia coli XL1-Blue was investigated. Two expression plasmids harbouring Ralstonia eutropha P(3HB) biosynthesis genes (phaCAB(Re)) downstream of an inducible trc promoter, pTrcphaCAB(Re) and pJRDTrcphaCAB(Re) were constructed using the high copy number plasmid pTrc99a and the low copy number plasmid pJRDTrc1, respectively. These plasmids and the constitutive expression plasmid harbouring phaCAB(Re) genes (pSYL105) were individually introduced into E. coli XL1-Blue, and a comparative study for P(3HB) production from glucose using a 10-1 fermentor was carried out. The highest P(3HB) productivity (2.8 g/l h) was obtained when the recombinant harbouring pJRDTrcphaCAB(Re) was cultured with the induction of gene expression. The produced P(3HB) had extremely high weight-average molecular weights ranging from 3.5 x 10 to 5.0 x 10(6). with relatively low polydispersities of around 1.5. The molecular weights remained nearly unchanged during the course of cultivation from 12 to 54 h, suggesting that a chain-transfer reaction took place to regulate the length of polymer chains within the E. coli cells. (C) 2004 Elsevier Ltd. All rights reserved.
ELSEVIER SCI LTD, 2005年01月, POLYMER DEGRADATION AND STABILITY, 87 (1), 161 - 169, 英語研究論文(学術雑誌)
High yield production of polyhydroxyalkanoates (PHAs) by Ralstonia eutropha H16 and its recombinant strain PHB(-)4/pJRDEE32d13 (a PHA-negative mutant harboring Aeromonas caviae PHA synthase gene, phaC(Ac)) from renewable inexpensive soybean oil was investigated. The PHA production by the wild-type strain H16 was achieved with a high dry cells weight (118-126 g/l) and a high poly[(R)-3-hydroxybutyrate] [P(3HB)] content per dry cells of 72-76% (w/w). A copolymer of 3HB with 5 mol% (R)-3-hydroxyhexanoate, P(3HB-co-5 mol% 3HHx), could be produced from soybean oil as a sole carbon source by the recombinant strain PHB(-)4/pJRDEE32d13 with a high dry cells weight (128-138 g/l) and a high PHA content of 71-74% (w/w). The reproducible results of PHA production in the presence of soybean oil as a sole carbon source was obtained with a high yield at a range of 0.72 to 0.76 g-PHA per g-soybean oil used. (C) 2003 Elsevier Ltd. All rights reserved.
ELSEVIER SCI LTD, 2004年01月, POLYMER DEGRADATION AND STABILITY, 83 (1), 79 - 86, 英語研究論文(学術雑誌)
cis-Aconitic acid decarboxylase (CAD) was assumed to be a key enzyme in the production of itaconic acid by comparing the activity of CAD from Aspergillus terreus TN484-M1 with that of CAD from the low-itaconate yielding strain Aspergillus terreus CM85J. The constitutive CAD was purified to homogeneity from A. terreus TN484-M1 by ammonium sulfate fractionation, and column chromatography on DEAE-toyopearl, Butyl-toyopearl, and Sephacryl S200HR, and then characterized. A molecular mass of 55 kDa for the native enzyme was determined by SDS-PAGE. The enzymic activity was optimal at a pH of 6.2 and temperature of 45degreesC. The K-m value for cis-aconitic acid was determined as 2.45 mM (pH 6.2, 37degreesC). The enzyme was completely inactivated by Hg+, Cu2+, Zu(2+),p-chloromercuribenzoate, and 5,5'-dithio-bis(2-nitrobenzoate).
SOC BIOSCIENCE BIOENGINEERING JAPAN, 2002年07月, JOURNAL OF BIOSCIENCE AND BIOENGINEERING, 94 (1), 29 - 33, 英語[査読有り]
研究論文(学術雑誌)
cis-Aconitic acid decarboxylase (CAD) was assumed to be a key enzyme in the production of itaconic acid by comparing the activity of CAD from Aspergillus terreus TN484-M1 with that of CAD from the low-itaconate yielding strain Aspergillus terreus CM85J. The constitutive CAD was purified to homogeneity from A. terreus TN484-M1 by ammonium sulfate fractionation, and column chromatography on DEAE-toyopearl, Butyl-toyopearl, and Sephacryl S200HR, and then characterized. A molecular mass of 55 kDa for the native enzyme was determined by SDS-PAGE. The enzymic activity was optimal at a pH of 6.2 and temperature of 45degreesC. The K-m value for cis-aconitic acid was determined as 2.45 mM (pH 6.2, 37degreesC). The enzyme was completely inactivated by Hg+, Cu2+, Zu(2+),p-chloromercuribenzoate, and 5,5'-dithio-bis(2-nitrobenzoate).
SOC BIOSCIENCE BIOENGINEERING JAPAN, 2002年07月, JOURNAL OF BIOSCIENCE AND BIOENGINEERING, 94 (1), 29 - 33, 英語[査読有り]
研究論文(学術雑誌)
This paper deals with studies on ε-poly-L-lysine (ε-PL) production in an airlift bioreactor (ABR) using Streptomyces albulus S410 (S410) to minimize the production cost including the downstream processing of ε-PL. In a 5-l ABR, 30 g/l of ε-PL was produced with a power consumption of 0.3 kW/m^3, the production level being similar to that in a 5-l jar fermentor with a power consumption of 8.0 kW/m^3. Furthermore, the leakage of intracellular nucleic acid (INA)-related substances into the culture broth in the ABR was less than that in the jar fermentor. Due to the high-level power consumption (8.0 kW/m^3) in the jar fermentor, the morphology of the cells changed from the pellet to filament form due to the extensive shear stress arising from continuous agitation, thereby increasing the leakage of the INA-related substances into the culture broth. This suggested that ABR would have an advantage in the low-cost production of ε-PL over stirred tank type reactors (STR).
公益社団法人日本生物工学会, 2002年03月, Journal of bioscience and bioengineering, 93 (3), 274 - 280, 英語[査読有り]
研究論文(学術雑誌)
Epsilon-poly-L-lysine(以下ePL)は、アルカロイド生産菌の検索の過程で、Streptomyces albulusの生産するL-lysineのホモポリマー(n=25-30)として酒井らにより初めて見出されたePLは必須アミノ酸であるリジンのホモポリマーであるので安全性が高くかつカチオン含量が高いので、さらにHレタリー用品、食品添加物、化粧品、医寮晶、農薬晶、電子材料などの広範な用途が期待され、ePLの工業生産プロセスが重要になってくる。我々は、培養中のpHやグルコースの残存濃度などの培養条件を検討し、ePLの高収率生産プロセスを構築することを試みた。さらに、低コスト化に向けた高純度など一PL生産システムの構築を実現するためにエアリフト型バイオリアククーでの発酵生産を検討した。
岐阜大学機関リポジトリ, 2002年, 農学 甲第275号, 英語[査読有り]
学位論文(博士)
An optimal feed rate profile of a substrate (tylosin) for a novel antibiotic, acetyl-isovaleryl tylosin (AIV) production process was investigated. In the first step of optimization, a kinetic model for production of AIV from tylosin by Streptomyces thermotolerans was established properly using the least square method, followed by the confirmation that the proposed model could be used to predict the production process of AIV from tylosin. An objective function, state equations and an inequality constraint with respect to the tylosin feeding rate profile were applied to maximize the amount of AIV produced from tylosin in a fed-batch culture. The optimized tylosin feeding rate profile was determined using a direct iterative search algorithm based on the modified complex method. The simulation of AIV production at the optimal tylosin feeding profile indicates that the final amount of AIV is expected to be about 30% higher than that at the conventional constant tylosin feeding rate, which was also confirmed experimentally using a 30-l jar fermentor.
SOC BIOSCIENCE BIOENGINEERING JAPAN, 2001年05月, JOURNAL OF BIOSCIENCE AND BIOENGINEERING, 91 (5), 504 - 508, 英語研究論文(学術雑誌)
The enhancement of epsilon -poly-L-lysine (epsilon -PL) production by Streptomyces albulus strain no. 410 (S410) by means of a pH control strategy was investigated. S140 cells produce epsilon -PL at a high concentration if the culture pH remains at about 4.0; however, if it shifts to higher than 4.0, the accumulated epsilon -PL is depolymerized. We therefore suggest a pH control strategy for cell growth and epsilon -PL production aimed at increasing the amount of epsilon -PL produced. The cultivation was divided into two control phases. In phase I, cell growth was accelerated by maintaining the pH at higher than 5.0; in phase II, epsilon -PL production was increased by maintaining the pH at about 4.0. To avoid an increase in the pH during phase II as a result of glucose depletion, the glucose concentration was kept at around 10 g/l by glucose feeding. This control strategy enhanced the production of h-PL to 48.3 g/l from 5.7 g/l in the case of batch culture.
SOC BIOSCIENCE BIOENGINEERING JAPAN, 2001年02月, JOURNAL OF BIOSCIENCE AND BIOENGINEERING, 91 (2), 190 - 194, 英語研究論文(学術雑誌)
The enhancement of epsilon -poly-L-lysine (epsilon -PL) production by Streptomyces albulus strain no. 410 (S410) by means of a pH control strategy was investigated. S140 cells produce epsilon -PL at a high concentration if the culture pH remains at about 4.0; however, if it shifts to higher than 4.0, the accumulated epsilon -PL is depolymerized. We therefore suggest a pH control strategy for cell growth and epsilon -PL production aimed at increasing the amount of epsilon -PL produced. The cultivation was divided into two control phases. In phase I, cell growth was accelerated by maintaining the pH at higher than 5.0; in phase II, epsilon -PL production was increased by maintaining the pH at about 4.0. To avoid an increase in the pH during phase II as a result of glucose depletion, the glucose concentration was kept at around 10 g/l by glucose feeding. This control strategy enhanced the production of h-PL to 48.3 g/l from 5.7 g/l in the case of batch culture.
SOC BIOSCIENCE BIOENGINEERING JAPAN, 2001年02月, JOURNAL OF BIOSCIENCE AND BIOENGINEERING, 91 (2), 190 - 194, 英語[査読有り]
研究論文(学術雑誌)
Corn starch and soybean oil are suitable carbon sources for the production of tetracycline by Streptomyces aureofacience CG-1. However, it could not produce more than 6 g/l of tetracycline even if initial corn starch concentration was increased to more than 100 g/l. It was confirmed by shaking flask experiments that the k(L)a in a mixture of 2% soybean oh in water was four folds compared with that without soybean oil. With the addition of soybean oil to the starch medium in a shaking flask, tetracycline production was significantly improved. By scaling-up to a 5.5-l airlift bioreactor from 500-ml Erlenmeyer flask, more than 10 g/l of tetracycline was produced with the addition of 60 g/l of soybean oil to the medium containing 100 g/l of corn starch. The dissolved oxygen level in the airlift bioreactor containing soybean oil was higher than that without soybean oil. This suggests that soybean oil is not only a suitable carbon source but is also a surface-active agent which may accelerate the oxygen transfer. This may lead to the possibility of the enhanced production of tetracycline at a low cost in airlift bioreactor.
SOC BIOSCIENCE BIOENGINEERING JAPAN, 1999年06月, JOURNAL OF BIOSCIENCE AND BIOENGINEERING, 87 (6), 825 - 827, 英語研究論文(学術雑誌)
A simple kinetics of soybean on consumption and cephamycin C production in Streptomyces sp. culture using a mineral support is proposed in this study. The mineral support was used for both suspending the soybean oil as fine oil droplets and immobilizing mycelia. The optimum concentrations of oil and mineral support for obtaining the maximum cephamycin C production were determined to be 50 and 15 g/l, respectively, by the proposed kinetics. At the optimal concentrations, the concentration of cephamycin C estimated from the proposed model and from the experimental data was 2.82 and 2.80 g/l respectively.,The results of the simulation coincided well with the experimental data for various concentrations of the soybean oil and the support. This demonstrates that our model can explain the kinetics of a culture using vegetable oil-as the carbon source and mineral support for both oil suspension and mycelial immobilization.
SOC BIOSCIENCE BIOENGINEERING JAPAN, 1999年03月, JOURNAL OF BIOSCIENCE AND BIOENGINEERING, 87 (3), 390 - 393, 英語研究論文(学術雑誌)
The effect of an oxygen vector on the oxygen transfer rate in air-lift bioreactor was evaluated using the ratio of the volumetric oxygen transfer coefficient to the volumetric fraction of the oxygen vector. When n-dodecane and perfluorocarbon were added at final concentrations of 3% and 2% (v/v), respectively, the oxygen transfer rate reached a maximum value. By addition of 3% (v/v) of n-dodecane to the yeast fermentation, the yeast concentration increased to 26.2 g/l which was 20% higher than in the case of fermentation in the absence of the oxygen vector.
SOC FERMENTATION BIOENGINEERING, JAPAN, 1997年, JOURNAL OF FERMENTATION AND BIOENGINEERING, 84 (2), 176 - 178, 英語研究論文(学術雑誌)
When lignocellulosic biomass is utilized as a fermentative substrate to produce biochemicals, the existence of a yeast strain resistant to inhibitory chemical compounds (ICCs) released from the biomass becomes critical. To achieve the purpose, in this study, Saccharomyces yeast strains from a NBRC yeast culture collection were used for exploration and evaluated in two different media containing ICCs that mimic one another but resemble the hydrolysate of real biomass. Among them, S. cerevisiae F118 strain shows robustness upon the fermentation with unique flocculation trait that was strongly responsive to ICC stress. When this strain was cultured in the presence of ICCs, its cell wall hydrophobicity increased dramatically, and reduced significantly when the ICCs were depleted, demonstrating that cell-surface hydrophobicity can also act as an adaptive response to the ICCs. Cells from the strain with the highest cell-wall hydrophobicity displayed progressively stronger flocculation, indicating that the F118 strain is having unique robustness under ICC stress. Gene expression perturbation analysis revealed that mot3 gene encoding regulatory Mot3p from the F118 strain was expressed in response to the concentration of ICCs. This gene was found to control expression of ygp1 gene that encoding Ygp1p, one of cell wall proteins. Deep sequencing analysis revealed that the Mot3p of the F118 strain features a unique insertion and deletion of nucleotides that encode glutamine or asparagine residues, particularly in N-terminal domain, as determined by comparison to the Mot3p sequence from the S288c strain, which was employed as a control strain. Furthermore, the cell wall hydrophobicity of the S288c strain was greatly enhanced and became ICC-responsive after gene swapping with the mot3 gene from the F118 strain. The gene-swapped S288c strain fermented 6-fold faster than the wild-type strain, producing 14.5 g/L of ethanol from 30 g/L of glucose consumed within 24 h in a medium containing the ICCs. These such modifications to Mot3p in unique locations in its sequence have a potential to change the expression of a gene involved in cell wall hydrophobicity and boosted the flocculation response to ICC stress, allowing for the acquisition of extraordinary robustness.
2022年03月04日, Metabolic engineering, 72, 82 - 96, 英語, 国際誌[査読有り]
研究論文(学術雑誌)
Background: Mannans represent the largest hemicellulosic fraction in softwoods and also serve as carbohydrate stores in various plants. However, the utilization of mannans as sustainable resources has been less advanced in sustainable biofuel development. Based on a yeast cell surface-display technology that enables the immobilization of multiple enzymes on the yeast cell walls, we constructed a recombinant Saccharomyces cerevisiae strain that co-displays beta-mannanase and beta-mannosidase; this strain is expected to facilitate ethanol fermentation using mannan as a biomass source. Results: Parental yeast S. cerevisiae assimilated mannose and glucose as monomeric sugars, producing ethanol from mannose. We constructed yeast strains that express tethered beta-mannanase and beta-mannosidase; co-display of the two enzymes on the cell surface was confirmed by immunofluorescence staining and enzyme activity assays. The constructed yeast cells successfully hydrolyzed 1,4-beta-D-mannan and produced ethanol by assimilating the resulting mannose without external addition of enzymes. Furthermore, the constructed strain produced ethanol from 1,4-beta-D-mannan continually during the third batch of repeated fermentation. Additionally, the constructed strain produced ethanol from ivory nut mannan; ethanol yield was improved by NaOH pretreatment of the substrate. Conclusions: We successfully displayed beta-mannanase and beta-mannosidase on the yeast cell surface. Our results clearly demonstrate the utility of the strain co-displaying beta-mannanase and beta-mannosidase for ethanol fermentation from mannan biomass. Thus, co-tethering beta-mannanase and beta-mannosidase on the yeast cell surface provides a powerful platform technology for yeast fermentation toward the production of bioethanol and other biochemicals from lignocellulosic materials containing mannan components.
BIOMED CENTRAL LTD, 2016年09月, BIOTECHNOLOGY FOR BIOFUELS, 9 (Sept), 9:188 (WEB ONLY), 英語The enhancement of ε-poly-L-lysine (ε-PL) production by Streptomyces albulus strain no.410 (S410) by means of a pH control strategy was investigated. S140 cells produce ε-PL at a high concentration if the culture pH remains at about 4.0; however, if it shifts to higher than 4.0, the accumulated ε-PL is depolymerized. We therefore suggest a pH control strategy for cell growth and ε-PL production aimed at increasing the amount of ε-PL produced. The cultivation was divided into two control phases. In phase I, cell growth was accelerated by maintaining the pH at higher than 5.0; in phase II, ε-PL production was increased by maintaining the pH at about 4.0. To avoid an increase in the pH during phase II as a result of glucose depletion, the glucose concentration was kept at around 10 g/l by glucose feeding. This control strategy enhanced the production of ε-PL to 48.3 g/l from 5.7 g/l in the case of batch culture.
公益社団法人日本生物工学会, 2001年02月, Journal of bioscience and bioengineering, 91 (2), 190 - 194, 英語学術書
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