JBB : Journal of Bioscience and Bioengineering

JBB Vol. 126表紙  



  • Characteristics of heterotrophic nitrification and aerobic denitrification bacterium Acinetobacter sp. T1 and its application for pig farm wastewater treatment

    Publication date: Available online 20 September 2018

    Source: Journal of Bioscience and Bioengineering

    Author(s): Shaohua Chen, Shuyan He, Chenjie Wu, Dongyun Du

    A novel heterotrophic bacterium was isolated from activated sludge of a pig farm wastewater treatment plant and identified as Acinetobacter sp. T1. It exhibited efficient heterotrophic nitrification and aerobic denitrification capability to utilize ammonium, nitrate or nitrite as the sole nitrogen source, and their removal rates were 12.08, 5.53 and 1.69 mg/L/h, respectively. Furthermore, the optimal conditions for the heterotrophic nitrification process were sodium citrate as the carbon source, C/N mass ratio of 10, pH of 8.5 and dissolved oxygen (DO) concentration of 5.1 mg/L. Only trace amounts of nitrate and nitrite were observed during the process. When the aerobic tank of the A2O process of a pig farm wastewater treatment plant was inoculated with traditional activated sludge, the average removals of COD, NH4+- N and TN in the effluent were 30%, 15% and 16%, respectively, which was much lower than that of inoculated with strain T1, the increase was statistically significant, indicating a great potential of strain T1 for full-scale applications.

  • Synthesis and characterization of Ogataea thermomethanolica alcohol oxidase immobilized on barium ferrite magnetic microparticles

    Publication date: Available online 20 September 2018

    Source: Journal of Bioscience and Bioengineering

    Author(s): Natthaya Mangkorn, Pattanop Kanokratana, Niran Roongsawang, Apirat Laobuthee, Navadol Laosiripojana, Verawat Champreda

    Alcohol oxidase catalyzes the oxidation of primary alcohols into the corresponding aldehydes, making it a potential biocatalyst in the chemical industry. However, the high production cost and poor operational stability of this enzyme are limitations for industrial application. Immobilization of enzyme onto solid supports is a useful strategy for improving enzyme stability. In this work, alcohol oxidase from the thermotolerant methylotrophic yeast Ogataea thermomethanolica (OthAOX) was covalently immobilized onto barium ferrite (BaFe12O19) magnetic microparticles. Among different conditions tested, the highest immobilization efficiency of 71.0 % and catalytic activity of 34.6 U/g was obtained. Immobilization of OthAOX onto magnetic support was shown by Fourier-Transformed infrared microscopy, scanning electron microscopy and X-ray diffraction. The immobilized OthAOX worked optimally at 55 °C and pH 8.0. Immobilization also improved thermostability, in which >65% of the initial immobilized enzyme activity was retained after 24 h pre-incubation at 45 °C. The immobilized enzyme showed a greater catalytic efficiency for oxidation of methanol and ethanol than free enzyme. The immobilized enzyme could be recovered by magnetization and recycled for at least three consecutive batches, after which 70% activity remained. The properties of the immobilized enzyme suggest its potential industrial application for synthesis of aldehyde.

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  • Two NADH-dependent (S)-3-hydroxyacyl-CoA dehydrogenases from polyhydroxyalkanoate-producing Ralstonia eutropha

    Publication date: Available online 19 September 2018

    Source: Journal of Bioscience and Bioengineering

    Author(s): Mutsumi Segawa, Cheng Wen, Izumi Orita, Satoshi Nakamura, Toshiaki Fukui

    Ralstonia eutropha H16 contains both NADH- and NADPH-dependent reduction activities to acetoacetyl-CoA, and the NADPH-dependent activity is mediated by PhaB paralogs with (R)-stereospecificity providing (R)-3-hydroxybutyryl (3HB)-CoA monomer for poly((R)-3-hydroxybutyrate) synthesis. In contrast, the gene encoding the NADH-dependent enzyme has not been identified to date. This study focused on the NADH-dependent dehydrogenase with (S)-stereospecificity in R. eutropha, as the (S)-specific reduction of acetoacetyl-CoA potentially competed with the polyester biosynthesis via (R)-3HB-CoA. The NADH-dependent reduction activity decreased to one-half when the gene for H16_A0282 (PaaH1), one of two homologs of clostridial NADH-3HB-CoA dehydrogenase, was deleted. The enzyme responsible for the remaining activity was partially purified and identified as H16_A0602 (Had) belonging to a different family from PaaH1. Gene disruption analysis elucidated that most of the NADH-dependent activity was mediated by PaaH1 and Had. The kinetic analysis using the recombinant enzymes indicated that PaaH1 and Had were both NADH-dependent 3-hydroxyacyl-CoA dehydrogenases with rather broad substrate specificity to 3-oxoacyl-CoAs of C4 to C8. The deletion of had in the R. eutropha strain previously engineered for biosynthesis of poly((R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate) led to decrease in the C6 composition of the copolyester synthesized from soybean oil, suggesting the role of Had in (S)-specific reduction of 3-oxohexanoyl-CoA with reverse β-oxidation direction. Crotonase ((S)-specific enoyl-CoA hydratase) in R. eutropha H16 was also partially purified and identified as H16_A3307.

  • Effects of ammonium and/or sulfide on methane production from acetate or propionate using biochemical methane potential tests

    Publication date: Available online 19 September 2018

    Source: Journal of Bioscience and Bioengineering

    Author(s): Li Tan, Qiu-Shi Cheng, Zhao-Yong Sun, Yue-Qin Tang, Kenji Kida

    The inhibitory effects of ammonium and sulfide on the methane production using acetate or propionate as a carbon source were investigated under different pH and temperature conditions. The methane production rate, duration of the lag phase, and inhibition threshold limit during methane production were estimated using the Gompertz equation and inhibitor mathematical model. The methane production rates at 53°C were 2.3–2.7 times higher than those at 35°C in the case of non-inhibitors. Increasing the NH4+ and/or S2− concentration decreased the methane production rate and increased the duration of the lag phase. For methane fermentation that was not acclimated to high NH4+ concentration, the critical NH4+ concentration beyond which methane fermentation would stop was 4000–5650 mg/L, depending on the pH, temperature, and carbon source. When NH4+ and S2− were coexistent, the critical NH4+ concentration decreased to approximately 3800 mg/L when propionate was used and to approximately 4450 mg/L when acetate was used. However, no synergistic effect of NH4+ and S2− on the methane production rate was found at an NH4+ concentration of < 5000 mg/L and S2− concentration of 50 mg/L.

  • Roles of aging in the production of light-flavored Daqu

    Publication date: Available online 18 September 2018

    Source: Journal of Bioscience and Bioengineering

    Author(s): Guangsen Fan, Zhilei Fu, Baoguo Sun, Yuhang Zhang, Xinlei Wang, Yanqiu Xia, Mingquan Huang, Xiuting Li

    Daqu, a complex starting material used for Baijiu production, contains microorganisms, enzymes, and volatile compounds. An important part of Daqu production is aging, but the physicochemical and microbial changes during aging remain largely unknown. This study characterized “aging” according to physicochemical parameters, volatile compounds, and microbial communities. Aging was found to aid in the stabilization of the physicochemical parameters. Solid-phase microextraction-gas chromatography-mass spectrometry was used to detect 72 types of volatile compounds, which were predominantly alcohols, esters, aldehydes, alkenes, and alkanes. During aging, these compounds changed considerably, but their structures eventually stabilized. A high-throughput sequencing approach was used to analyze the changing composition of the microbial communities. In general, aging helped to enrich and stabilize the microbial population for making Baijiu. A total of 35 bacteria were detected as prokaryotic; among these, 15 had a diversity abundance ratio of more than 1%. The dominant bacteria were from the genus Pantoea, but these decreased with aging, while bacteria from Lactobacillus and Weissella increased. After aging for 2 months, Pantoea, Lactobacillus and Weissella accounted for 0.4%, 54.0%, and 18.9%, respectively. A total of 12 eukaryotic yeast and fungi were detected, the most abundant of which were Incertae_Sedis_incertae_sedis, Saccharomycopsis, Trichocomaceae_unclassified, Pichia, Tremellales_unclassified, and Galactomyces. During aging, the levels of Trichocomaceae_unclassified, Saccharomycopsis, and Galactomyces initially decreased but then increased. Pichia stayed unchanged as aging progressed. In conclusion, aging led to rebalanced interactions among Daqu microbes and was important in improving Daqu quality and ensuring its stability.

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  • Searching for high-binding peptides to bile acid for inhibition of intestinal cholesterol absorption using principal component analysis

    Publication date: Available online 18 September 2018

    Source: Journal of Bioscience and Bioengineering

    Author(s): Masako Ito, Kazunori Shimizu, Hiroyuki Honda

    We previously proposed a new method for exploring functional peptides using both spot-synthesis peptide libraries and principal component analysis (PCA). Here, we applied these methods to determine if high-binding 6-mer peptides can be used on bile acid for the inhibition of intestinal cholesterol absorption. We used a binding assay of 512 basal 4-mer peptides to bile acid, and from these selected high-binding and low-binding peptides. PCA was performed on data from both these binding groups and many physicochemical variables of the 512 peptides tested, and then through this, the variables were reduced to two principal components (PCs). The peptides were plotted on the PCA chart, and we identified distinct clusters of high- and low-binding regions. These PCA regions were applied to 6-mer random peptides, and we identified 6-mer peptides with high and low binding capacity to bile acid. We confirmed that the average fluorescence intensity of high-binding peptides was 3.0-fold higher than that of low-binding peptides. We succeeded in identifying 6-mer peptides with high and low-binding affinity based on the PCA analysis of 4-mer peptides. These results were compared and discussed with regard to those acquired by our previous computational analysis based on neural networks.

  • Glucose production from cellulose through biological simultaneous enzyme production and saccharification using recombinant bacteria expressing the β-glucosidase gene

    Publication date: Available online 17 September 2018

    Source: Journal of Bioscience and Bioengineering

    Author(s): Shunsuke Ichikawa, Maiko Ichihara, Toshiyuki Ito, Kazuho Isozaki, Akihiko Kosugi, Shuichi Karita

    Efficient cellulosic biomass saccharification technologies are required to meet biorefinery standards. Biological simultaneous enzyme production and saccharification (BSES), which is glucose production from cellulosic biomass by Clostridium thermocellum, can be a reliable cellulose saccharification technology for biorefineries. However, the current BSES processes require purified β-glucosidase supplementation. In this study, recombinant bacteria expressing the β-glucosidase gene were developed and directly applied to BSES. The engineered Escherichia coli expressing the thermostable β-glucosidase gene from Thermoanaerobacter brockii exhibited 0.5 U/ml of β-glucosidase activities. The signal peptide sequence of lytF gene from Bacillus subtilis was the most appropriate for the β-glucosidase secretion from Brevibacillus choshinensis, and the broth exhibited 0.74 U/ml of β-glucosidase activities. The engineered E. coli and B. choshinensis expressing the thermostable β-glucosidase gene produced 47.4 g/L glucose and 49.4 g/L glucose, respectively. Glucose was produced by the hydrolysis of 100 g/L Avicel cellulose for 10 days through BSES, and the product yield was similar to that obtained through BSES with purified β-glucosidase supplementation. Our findings indicate that the direct supplementation of β-glucosidase using bacterial cells expressing β-glucosidase gene or their broth was applicable to BSES, suggesting the potential of this process as a cost-effective approach to cellulose saccharification.

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  • Highly efficient deproteinization with an ammonifying bacteria Lysinibacillus fusiformis isolated from brewery spent diatomite

    Publication date: Available online 15 September 2018

    Source: Journal of Bioscience and Bioengineering

    Author(s): Xiaoxi Gong, Weijun Tian, Jie Bai, Kaili Qiao, Jing Zhao, Liang Wang

    To explore a new method for bio-regeneration of high-protein brewery spent diatomite, an ammonifying bacteria (BSD1) was screened out from it and identified as Lysinibacillus fusiformis. The protein degradation characteristics of BSD1 was studied with rice protein as the sole nitrogen source. Maximum protein degradation activity was obtained when BSD1 was inoculated with an inoculum of 5% into a medium with glucose as carbon source and initial pH value of 7.0 and incubated at 30°C for 48 h. In this optimal condition, protein concentration decreased from 156.8 mg/L to 19.2 mg/L, and protein degradation efficiency of BSD1 reached 88%. Free amino acid analysis showed that the content of Phe, Tyr, Pro, Ala, Lys, Thr and His increased in protein degradation process. After degradation, NH4+N concentration producing in medium supernatant reached 232.2 mg/L. These results indicated the strain BSD1 could transform proteins into free amino acids and eventually convert them to ammonium or ammonia. Furthermore, strain BSD1 could also be used for deproteinization of brewery spent diatomite and 51% of proteins in spent diatomite were degraded. After biological deproteinization the specific surface area and total pore volume of diatomite improved obviously. These results illustrated that the application of strain BSD1 for bio-regeneration of high-protein brewery spent diatomite was efficient and feasible.

  • Identification and analysis of binding residues in the CBM68 of pullulanase PulA from Anoxybacillus sp. LM18-11

    Publication date: Available online 15 September 2018

    Source: Journal of Bioscience and Bioengineering

    Author(s): Yan Zeng, Hongchen Zheng, Yingying Shen, Jianyong Xu, Ming Tan, Fang Liu, Hui Song

    Carbohydrate binding module (CBM) as a kind of non-catalytic domain has significant effects on the substrate binding and catalytic properties of glycoside hydrolases. CBM68 of an Anoxybacillus sp. pullulanase (PulA) was identified as a new type of CBM in our previous studies. Then, four key substrate binding amino acid residues (Y14, V91, G92, and R96) were obtained by alanine substitutions in this work. Through kinetic analysis of the mutants, V91A and G92A showed significant reduction both in Km values and kcat values against pullulan. To further identify the changes of substrate affinities of V91A and G92A, devitalized mutants V91A-D413N and G92A-D413N were under measuring by surface plasmon resonance (SPR). Compared with that of PulA-D413N, the substrate affinities of V91A-D413N and G92A-D413N were improved by 1.6-fold and 2.2-fold, respectively. However, as to the product (maltotriose) binding force tested by the isothermal titration calorimetry (ITC), G92A showed higher binding force than that of V91A and PulA by 4.2-fold and 6.2-fold, respectively. That may cause G92A showing significantly lower catalytic efficiency than V91A and PulA. Moreover, four different kinds of amino acids (leucine, serine, glutamic acid and arginine) substitutions for V91 and G92 showed various changes both on the kinetic parameters and enzymatic properties, which demonstrated that V91 and G92 were the critical binding residues in the CBM68. The results of this study made contributed to the rational design for improving the catalytic efficiency of PulA.

  • Production of bio-hydrogen from dairy wastewater using pretreated landfill leachate sludge as an inoculum

    Publication date: Available online 15 September 2018

    Source: Journal of Bioscience and Bioengineering

    Author(s): Yee Meng Wong, Pau Loke Show, Ta Yeong Wu, Hui Yi Leong, Shaliza Ibrahim, Joon Ching Juan

    Bio-hydrogen production from wastewater using sludge as inoculum is a sustainable approach for energy production. This study investigated the influence of initial pH and temperature on bio-hydrogen production from dairy wastewater using pretreated landfill leachate sludge (LLS) as an inoculum. The maximum yield of 113.2 ± 2.9 mmol H2/g chemical oxygen demand (COD) (12.8 ± 0.3 mmol H2/g carbohydrates) was obtained at initial pH 6 and 37 °C. The main products of volatile fatty acids were acetate and butyrate with the ratio of acetate:butyrate was 0.4. At optimum condition, Gibb's free energy was estimated at −40 kJ/mol, whereas the activation enthalpy and entropy were 65 kJ/mol and 0.128 kJ/mol/l, respectively. These thermodynamic quantities suggest that bio-hydrogen production from dairy wastewater using pretreated LLS as inoculum was effective and efficient. In addition, genomic and bioinformatics analyses were performed in this study.

  • Anomalous cell migration triggers a switch to deviation from the undifferentiated state in colonies of human induced pluripotent stems on feeder layers

    Publication date: Available online 14 September 2018

    Source: Journal of Bioscience and Bioengineering

    Author(s): Eri Shuzui, Mee-Hae Kim, Masahiro Kino-oka

    Understanding the fundamental mechanisms that trigger deviation from the undifferentiated state of human induced pluripotent stem cells (hiPSCs) provides key strategies to maintain their undifferentiated state during cell expansion. We assessed deviation from the undifferentiated state in hiPSC colonies by measuring cell migration rates in colonies with deviation that were targeted by the end of culture, in a backward manner. Analyses of migration rates of single cells in colonies with deviation demonstrated that the distribution of migration rates at the region with occurrence of deviated cells had a broad or narrow range compared with those at the regions of undifferentiated cells. It was found that deviated cells in hiPSC colonies accidentally occurred consequent to the appearance of relatively fast or slow migrating cells at the peripheral or central region of colonies, reflecting disorders owing to cell migration anomalies in the hiPSC colony. Fluorescence microscopy for F-actin, paxillin, and E-cadherin clarified the localization of integrin-mediated and cadherin-mediated adhesions, introducing the concept that the occurrence and pattern of deviation in a colony were responsive to changes of cell migration in that colony. Furthermore, a major component of the nuclear lamina, laminA/C displayed a rim at the nuclear periphery in the regions with occurrence of deviated cells, concomitant with the actin cytoskeleton associated with integrin- and cadherin-mediated cell adhesion. These results showed that an anomaly of cell migration in hiPSC colonies led to the accidental appearance of deviated cells therein through alternation of the nuclear lamina and imbalance between cell–cell and cell-substrate interactions.

  • Densitometric quantification for the validation of decolorization of Disperse Orange ERL by lichen Parmelia sp.

    Publication date: Available online 7 September 2018

    Source: Journal of Bioscience and Bioengineering

    Author(s): Ashwini N. Kulkarni, Bhumika N. Bhalkar, Rahul V. Khandare, Mayur B. Kurade, Byong-Hun Jeon, Sanjay P. Govindwar

    Densitometric HPTLC quantification method was developed to validate the decolorization/biotransformation of Disperse Orange ERL and dye mixture by lichen Parmelia sp. which release several colored compounds during decolorization process, hence unable to use colorimetric estimation. Percent decolorization of Disperse Orange ERL and dye mixture by lichen Parmelia sp. was observed when estimated using developed high performance thin layer chromatography method. Limit of detection and limit of quantification for both dyes in mixture were obtained as 0.3 and 1 μg/μl, respectively. Area of peak of control Disperse Orange ERL was reduced by 43% after 12 h, 71% after 48 h and upto 82% after 72 h of incubation. Precision and repeatability of data elucidated the % relative standard deviation less than 3 for all the values thus indicating statistically acceptable. Biodegradation of dye and mixture was confirmed with FTIR analysis, i.e., altered fingerprinting spectral pattern.

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  • Mechanisms and characteristics of biofilm formation via novel DEAMOX system based on sequencing biofilm batch reactor

    Publication date: Available online 7 September 2018

    Source: Journal of Bioscience and Bioengineering

    Author(s): Hanyu Zhang, Rui Du, Shenbin Cao, Shuyin Wang, Yongzhen Peng

    A denitrifying ammonium oxidation (DEAMOX) process has been regarded as an innovative process to simultaneously treat ammonia and nitrate containing wastewaters, whereas very limited research has focused on its application in biofilm system. In this research, a novel DEAMOX process was established with fixed sponge carriers in a sequencing biofilm batch reactor (SBBR). To investigate biofilm formation process and characteristics can encourage further research on DEAMOX system optimization, deteriorated performance recovery strategies and application with actual wastewater. Total nitrogen removal efficiency was maintained at 93.0 % after 240 days of operation. With biofilm growth, the protein-like extracellular polymeric substances (EPS) and tightly-bound EPS (TB-EPS) of biofilms increased from 65.6 to 46.1, to 179.6 and 142.0 mg gVSS−1, respectively, revealing that protein-like substances and TB-EPS promote biofilm formation. The mechanism of biofilm formation was discussed by analyzing the morphological development and functional bacterial activities of biofilms. Furthermore, high anammox activity was obtained in biofilms with specific NH4+N removal rates over 4.29 mgN gVSS−1h−1, which were significantly higher than in suspended sludge (2.56 mgN gVSS−1h−1). Quantitative polymerase chain reaction results showed that the abundance of anammox bacteria in biofilms increased from 1.87 % to 11.48 % with biofilm growth. These results imply that mature biofilms formed on carriers and the anammox bacteria were sufficient enriched in DEAMOX-SBBR system.

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  • Enhanced production of d-lactate from mixed sugars in Corynebacterium glutamicum by overexpression of glycolytic genes encoding phosphofructokinase and triosephosphate isomerase

    Publication date: Available online 6 September 2018

    Source: Journal of Bioscience and Bioengineering

    Author(s): Yota Tsuge, Naoto Kato, Shogo Yamamoto, Masako Suda, Masayuki Inui

    The use of mixed sugars containing glucose and xylose in lignocellulosic biomass is desirable for the microbial production of chemicals and fuels. We investigated the effect of individual or simultaneous overexpression of glycolytic genes on d-lactate production from a mixture of glucose and xylose by a recombinant xylose-assimilating Corynebacterium glutamicum strain. The individual overexpression of genes encoding phosphofructokinase (PFK) and triosephosphate isomerase (TPI) increased d-lactate production rate by 71% and 34%, respectively, with corresponding increases (2.4- and 1.8-fold) in the glucose consumption; however, the amount of xylose consumed not altered. d-Lactate yield was also increased by 5.5%, but only in the strain overexpressing the gene encoding PFK. In the parent strain and the strains overexpressing the genes encoding PFK or TPI, a reduction in d-lactate production occurred at approximately 900 mM after 32 h. However, the strain that simultaneously overexpressed the genes encoding PFK and TPI continued to produce d-lactate after 32 h, with the eventual production of 1326 mM after production for 80 h in mineral salts medium. Our findings contribute to the cost-effective, large-scale production of d-lactate from mixed sugars.

  • Biochemical characterization of isoprene synthase from Ipomoea batatas

    Publication date: Available online 3 September 2018

    Source: Journal of Bioscience and Bioengineering

    Author(s): Meijie Li, Changqing Liu, Hailin Chen, Li Deng, Haibo Zhang, Rui Nian, Mo Xian

    The bio-production process of isoprene, an essential chemical used in industry, is strongly limited by isoprene synthase. In our previous work, relatively high isoprene production was observed with isoprene synthase from Ipomoea batatas (IspSib). In this work the biochemical properties of IspSib were analyzed and compared with those of isoprene synthase from Populus alba (IspSpa) and other species. Firstly, IspSib and IspSpa were expressed, purified, and identified by SDS-PAGE and western blot analysis. Secondly, pH and temperature dependence of IspSib were performed and an optimum pH of 8.6 and an optimum temperature of 42 °C were resulted. Mg2+ with optimum concentration of 56 mM was proved to be needed for enzyme activation. In addition, in vivo and in vitro study of the thermostabilities of IspSib and IspSpa were performed. The enzyme activity of IspSib and IspSpa dropped very rapidly after incubation at 30 °C; almost 80% enzyme activity of IspSib was lost after 20 min of incubation. Moreover, the Michaelis–Menten constant was measured. IspSib showed a lower Km, 0.2 mM, and a higher kcat, 0.37 s−1, as compared with IspSpa. The high catalytic efficiency, which was reflected by the high kcat/Km ratio, indicates that IspSib is a good candidate for the bio-isoprene production, while its thermal instability remains as a challenge. Enzyme engineering efforts, such as direction evolution or semi-rational evolution, are planned for further research.

  • Gas chromatography coupled with mass spectrometry-based metabolomics for the classification of tempe from different regions and production processes in Indonesia

    Publication date: September 2018

    Source: Journal of Bioscience and Bioengineering, Volume 126, Issue 3

    Author(s): Adinda Darwati Kadar, Pingkan Aditiawati, Made Astawan, Sastia Prama Putri, Eiichiro Fukusaki

    Tempe, a fermented soybean originally from Indonesia, is an excellent protein source with high nutritional quality. Differences in the production process and unique fermentation condition in different regions result in varieties of tempe. Despite its high cultural and economic values, there are very few studies on the characterization of tempe based on the differences of production process and geographical origin. Metabolomics is a powerful tool assessing food quality, food safety, and determination of origin and varietal differences. In this study, metabolomics is applied for the study of Indonesian tempe obtained from various regions and different production processes. Seventeen samples were collected from 6 different cities in Java Island, which were produced by local tempe crafters (traditional), semi-modern industry and modern industry. Untargeted metabolomics by gas chromatography coupled with mass spectrometry (GC/MS) was implemented to discriminate various kinds of tempe and identify metabolites that are associated with these differences. Results showed that tempe produced in different places clustered together according to the cities and their production category. Sugars and amino acids groups were found to be primary compounds that contributed to this result. This is the first report that address the metabolic differences between different varieties of tempe from different regions and production processes. The knowledge from this study is important for future development of tempe production.

  • Recovery of biotechnological products using aqueous two phase systems

    Publication date: September 2018

    Source: Journal of Bioscience and Bioengineering, Volume 126, Issue 3

    Author(s): Win Nee Phong, Pau Loke Show, Yin Hui Chow, Tau Chuan Ling

    Aqueous two-phase system (ATPS) has been suggested as a promising separation tool in the biotechnological industry. This liquid-liquid extraction technique represents an interesting advance in downstream processing due to several advantages such as simplicity, rapid separation, efficiency, economy, flexibility and biocompatibility. Up to date, a range of biotechnological products have been successfully recovered from different sources with high yield using ATPS-based strategy. In view of the important potential contribution of the ATPS in downstream processing, this review article aims to provide latest information about the application of ATPS in the recovery of various biotechnological products in the past 7 years (2010–2017). Apart from that, the challenges as well as the possible future work and outlook of the ATPS-based recovery method have also been presented in this review article.

  • Meiotic chromosomal recombination defect in sake yeasts

    Publication date: Available online 1 September 2018

    Source: Journal of Bioscience and Bioengineering

    Author(s): Hitoshi Shimoi, Yuta Hanazumi, Natsuki Kawamura, Miwa Yamada, Shohei Shimizu, Taro Suzuki, Daisuke Watanabe, Takeshi Akao

    Sake yeast strains are classified into Saccharomyces cerevisiae and have a heterothallic life cycle. This feature allows cross hybridization between two haploids to breed new strains with superior characteristics. However, cross hybridization of sake yeast is very difficult because only a few spores develop in a sporulation medium, and most of these spores do not germinate. We hypothesized that these features are attributable to chromosome recombination defect in meiosis, which leads to chromosome loss. To test this hypothesis, we examined meiotic recombination of sake yeast Kyokai no. 7 (K7) using the following three methods: (i) analysis of the segregation patterns of two heterozygous sites in the same chromosome in 100 haploid K7 strains; (ii) sequencing of the whole genomes of four haploid K7 strains and comparison of the bases derived from the heterozygosities; and (iii) construction of double heterozygous disruptants of CAN1 and URA3 on the chromosome V of K7 and the examination of the genotypes of haploids after sporulation. We could not detect any recombinant segregants in any of the experiments, which indicated defect in meiotic recombination in K7. Analyses after sporulation of the same double heterozygous disruptants of K6, K9, and K10 also indicated meiotic recombination defect in these strains. Although rapamycin treatment increased the sporulation efficiency of K7, it did not increase the meiotic recombination of the double heterozygous K7. Moreover, the spo13 disruptant of the K7 derivative produced two spore asci without meiotic recombination. These results suggest that sake yeasts have defects in meiotic recombination machinery.

  • Exopolysaccharides from the fungal endophytic Fusarium sp. A14 isolated from Fritillaria unibracteata Hsiao et KC Hsia and their antioxidant and antiproliferation effects

    Publication date: Available online 1 September 2018

    Source: Journal of Bioscience and Bioengineering

    Author(s): Feng Pan, Kai Hou, Dan-Dan Li, Tian-Jiao Su, Wei Wu

    Exopolysaccharides (EPSs) are high-molecular-weight carbohydrates with a wide range of biophysiological activities, such as antioxidant activity, immunostimulatory activity, antitumor activity, hepatoprotective activity, and antifatigue effects. In the present work, two water-soluble EPSs, namely, A14EPS-1 and A14EPS-2, were isolated and purified from the fungal endophytic strain A14 using ethanol precipitation, DEAE-cellulose ion exchange chromatography and Sepharose G-150 gel filtration chromatography. A14EPS-1 (∼2.4 × 104 Da, the major fraction) was mainly composed of mannose, rhamnose, glucose, galactose, xylose and arabinose with a molar ratio of 0.31:0.55:10.00:0.34:0.03:0.06. The major monosaccharide of A14EPS-1 was pyranose, which was connected by α-glycosidic linkages. And the side chains of A14EPS-1 may be composed of rhamnose, arabinose, glucose and galactose; moreover, the backbone of A14EPS-1 may be composed of rhamnose, xylose, arabinose and glucose. A14EPS-2 (∼0.5 × 104 Da) was mainly composed of mannose, rhamnose, glucose, galactose, xylose and arabinose in a ratio of 0.16:0.88:10.00:0.39:0.06:0.06. Pyranose was observed in both the α- and β-configurations in A14EPS-2, and the α configuration was dominant. In addition, the results of the bioactivity assays indicated that both A14EPS-1 and A14EPS-2 had moderate antioxidant activity in vitro, and A14EPS-2 showed a moderate antiproliferation effect on human hepatocellular carcinoma HepG2 cells.

  • Epipremnum aureum and Dracaena braunii as indoor plants for enhanced bio-electricity generation in a plant microbial fuel cell with electrochemically modified carbon fiber brush anode

    Publication date: September 2018

    Source: Journal of Bioscience and Bioengineering, Volume 126, Issue 3

    Author(s): Pranab Jyoti Sarma, Kaustubha Mohanty

    In this study, two different unexploited indoor plants, Epipremnum aureum and Dracaena braunii were used to produce clean and sustainable bio-electricity in a plant microbial fuel cell (PMFC). Acid modified carbon fiber brush electrodes as well as bare electrodes were used in both the PMFCs. A bentonite based clay membrane was successfully integrated in the PMFCs. Maximum performance of E. aureum was 620 mV which was 188 mV higher potential than D. braunii. The bio-electricity generation using modified electrode was 154 mV higher than the bare carbon fiber, probably due to the effective bacterial attachment to the carbon fiber owing to hydrogen bonding. Maximum power output of 15.38 mW/m2 was obtained by E. aureum with an internal resistance of 200 Ω. Higher biomass yield was also obtained in case of E. aureum during 60 days of experiment, which may correlate with the higher bio-electricity generation than D. braunii.

    Graphical abstract

    Graphical abstract for this article