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1.
Chelladurai Rathnasingh Jong Myoung Park Duk-ki Kim Hyohak Song Yong Keun Chang 《Biotechnology letters》2016,38(6):975-982
Objectives
To improve the production of 2,3-butanediol (2,3-BD) in Klebsiella pneumoniae, the genes related to the formation of lactic acid, ethanol, and acetic acid were eliminated.Results
Although the cell growth and 2,3-BD production rates of the K. pneumoniae ΔldhA ΔadhE Δpta-ackA strain were lower than those of the wild-type strain, the mutant produced a higher titer of 2,3-BD and a higher yield in batch fermentation: 91 g 2,3-BD/l with a yield of 0.45 g per g glucose and a productivity of 1.62 g/l.h in fed-batch fermentation. The metabolic characteristics of the mutants were consistent with the results of in silico simulation.Conclusions
K. pneumoniae knockout mutants developed with an aid of in silico investigation could produce higher amounts of 2,3-BD with increased titer, yield, and productivity.2.
Lifei Chen Chunling Ma Ruiming Wang Jianlou Yang Haijie Zheng 《Biotechnology letters》2016,38(10):1769-1774
Objectives
To improve 1,3-propanediol (1,3-PD) production and reduce byproduct concentration during the fermentation of Klebsiella pneumonia.Results
Klebsiella. pneumonia 2-1ΔldhA, K. pneumonia 2-1ΔaldH and K. pneumonia 2-1ΔldhAΔaldH mutant strains were obtained through deletion of the ldhA gene encoding lactate dehydrogenase required for lactate synthesis and the aldH gene encoding acetaldehyde dehydrogenase involved in the synthesis of ethanol. After fed-batch fermentation, the production of 1,3-PD from glycerol was enhanced and the concentrations of byproducts were reduced compared with the original strain K. pneumonia 2-1. The maximum yields of 1,3-PD were 85.7, 82.5 and 87.5 g/l in the respective mutant strains.Conclusion
Deletion of either aldH or ldhA promoted 1,3-PD production in K. pneumonia.3.
Xuechang Wu Lijie Zhang Xinna Jin Yahong Fang Ke Zhang Lei Qi Daoqiong Zheng 《Biotechnology letters》2016,38(7):1097-1106
4.
Junhong Wei Jinjin Tian Guoqing Pan Jie Xie Jialing Bao Zeyang Zhou 《Biotechnology letters》2017,39(6):857-864
Objective
To develop a reliable and easy to use expression system for antibiotic production improvement of Streptomyces.Results
A two-compound T7 RNA polymerase-dependent gene expression system was developed to fulfill this demand. In this system, the T7 RNA polymerase coding sequence was optimized based on the codon usage of Streptomyces coelicolor. To evaluate the functionality of this system, we constructed an activator gene overexpression strain for enhancement of actinorhodin production. By overexpression of the positive regulator actII-ORF4 with this system, the maximum actinorhodin yield of engineered strain was 15-fold higher and the fermentation time was decreased by 48 h.Conclusion
The modified two-compound T7 expression system improves both antibiotic production and accelerates the fermentation process in Streptomyces. This provides a general and useful strategy for strain improvement of important antibiotic producing Streptomyces strains.5.
Objectives
To enhance acid tolerance of Candida glabrata for pyruvate production by engineering AMP metabolism.Results
The physiological function of AMP deaminase in AMP metabolism from C. glabrata was investigated by deleting or overexpresseing the corresponding gene, CgAMD1. At pH 4, CgAMD1 overexpression resulted in 59 and 51% increases in biomass and cell viability compared to those of wild type strain, respectively. In addition, the intracellular ATP level of strain Cgamd1Δ/CgAMD1 was down-regulated by 22%, which led to a 94% increase in pyruvate production. Further, various strengths of CgAMD1 expression cassettes were designed, thus resulting in a 59% increase in pyruvate production at pH 4. Strain Cgamd1Δ/CgAMD1 (H) was grown in a 30 l batch bioreactor at pH 4, and pyruvate reached 46.1 g/l.Conclusion
CgAMD1 overexpression plays an active role in improving acid tolerance and pyruvate fermentation performance of C. glabrata at pH 4.6.
Chengqian Zhu Xiao Jiang Yongqiang Zhang Jie Lin Shuilin Fu Heng Gong 《Biotechnology letters》2015,37(9):1783-1790
Objective
To improve 1,3-propanediol production in Klebsiella pneumoniae, the effects of puuC expression in lactate- and lactate/2,3-butanediol-deficient strains were assessed.Results
Overexpression of puuC (encoding an aldehyde dehydrogenase) inhibited 1,3-propanediol production and increased 3-hydroxypropionic acid formation in both lactate- and lactate/2,3-butanediol-deficient strains. An improvement in 1,3-propanediol production was only achieved in a lactate-deficient strain via moderate expression of puuC; at the end of the fermentation, 1,3-propanediol productivity increased by 14 % compared with the control. Further comparative analysis of the metabolic flux distributions in different strains indicated that 3-hydroxypropionic acid formation could play a considerable role in cell metabolism in K. pneumoniae.Conclusion
An improvement in 3-hydroxypropionic acid formation would be beneficial for cell metabolism, which can be accomplished by enhancing 1,3-propanediol productivity in a lactate-deficient strain via moderate expression of puuC.7.
Objectives
To reduce the amount of citrulline produced by arginine-consuming bacteria in the moromi mash during soy sauce production.Results
Bacillus amyloliquefaciens JY06, a salt-tolerant strain with high arginine consumption ability and low citrulline accumulation capacity, was isolated from moromi mash. The concentration of citrulline was decreased from 26.8 to 5.1 mM and ethyl carbamate in soy sauce, after sterilization, decreased from 97 to 17 μg kg?1 when B. amyloliquefaciens JY06 was added during fermentation. The aroma of the sauce was improved by increasing the ester content.Conclusions
B. amyloliquefaciens JY06 is a beneficial bacterium that can be used in soy sauce fermentation to eliminate ethyl carbonate and enhance the flavor of the sauce.8.
Wenwen Zhang Zhaohui Chen Mengmeng Wu Zhong Shi Feng Zhu Guoqiang li Ting Ma 《Biotechnology letters》2016,38(6):991-997
Objective
To improve the production of welan gum and obtain a carotenoid-free strain while reducing the fermentation and post-treatment costs.Results
The vitreoscilla globin (vgb) gene combined with the β-galactosidase (lacZ) promoter was inserted into the phytoene synthase (crtB) gene region of the chromosome in Alcaligenes sp. ATCC31555. When the recombinant strain was grown in a 5 l fermentor, welan gum was produced at 24 ± 0.4 g l?1 compared to 21 g ± 0.4 g l?1 in the wild type. Furthermore, the carotenoid-free welan gum produced using Alcaligenes sp. ATCC31555 VHb strain was less expensive with improved properties.Conclusions
Alcaligenes sp. ATCC31555 VHb strain was a better neutral welan-producing strain with a higher production than the wild-type strain.9.
Gbekeloluwa B. Oguntimein Miguel RodriguezJr. Alexandru Dumitrache Todd Shollenberger Stephen R. Decker Brian H. Davison Steven D. Brown 《Biotechnology letters》2018,40(2):303-308
Objective
To develop and prototype a high-throughput microplate assay to assess anaerobic microorganisms and lignocellulosic biomasses in a rapid, cost-effective screen for consolidated bioprocessing potential.Results
Clostridium thermocellum parent Δhpt strain deconstructed Avicel to cellobiose, glucose, and generated lactic acid, formic acid, acetic acid and ethanol as fermentation products in titers and ratios similar to larger scale fermentations confirming the suitability of a plate-based method for C. thermocellum growth studies. C. thermocellum strain LL1210, with gene deletions in the key central metabolic pathways, produced higher ethanol titers in the Consolidated Bioprocessing (CBP) plate assay for both Avicel and switchgrass fermentations when compared to the Δhpt strain.Conclusion
A prototype microplate assay system is developed that will facilitate high-throughput bioprospecting for new lignocellulosic biomass types, genetic variants and new microbial strains for bioethanol production.10.
Tinghong Ming Jiaojiao Han Yanyan Li Chenyang Lu Dihong Qiu Ye Li Jun Zhou Xiurong Su 《BMC microbiology》2018,18(1):216
Background
Lactobacillus plantarum, a versatile lactic acid-fermenting bacterium, isolated from the traditional pickles in Ningbo of China, was chosen for grass carp fermentation, which could also improve the flavor of grass carp. We here explored the central metabolic pathways of L. plantarum by using metabolomic approach, and further proved the potential for metabolomics combined with proteomics approaches for the basic research on the changes of metabolites and the corresponding fermentation mechanism of L. plantarum fermentation.Results
This study provides a cellular material footprinting of more than 77 metabolites and 27 proteins in L. plantarum during the grass carp fermentation. Compared to control group, cells displayed higher levels of proteins associated with glycolysis and nucleotide synthesis, whereas increased levels of serine, ornithine, aspartic acid, 2-piperidinecarboxylic acid, and fumarate, along with decreased levels of alanine, glycine, threonine, tryptophan, and lysine.Conclusions
Our results may provide a deeper understanding of L. plantarum fermentation mechanism based on metabolomics and proteomic analysis and facilitate future investigations into the characterization of L. plantarum during the grass carp fermentation.11.
Takuya Matsusako Yoshihiro Toya Katsunori Yoshikawa Hiroshi Shimizu 《Biotechnology for biofuels》2017,10(1):307
Background
Synechocystis sp. PCC 6803 is an attractive organism for the production of alcohols, such as isobutanol and ethanol. However, because stress against the produced alcohol is a major barrier for industrial applications, it is highly desirable to engineer organisms with strong alcohol tolerance.Results
Isobutanol-tolerant strains of Synechocystis sp. PCC 6803 were obtained by long-term passage culture experiments using medium containing 2 g/L isobutanol. These evolved strains grew on medium containing 5 g/L isobutanol on which the parental strain could not grow. Mutation analysis of the evolved strains revealed that they acquired resistance ability due to combinatorial malfunctions of slr1044 (mcpA) and slr0369 (envD), or slr0322 (hik43) and envD. The tolerant strains demonstrated stress resistance against isobutanol as well as a wide variety of alcohols such as ethanol, n-butanol, and isopentanol. As a result of introducing an ethanol-producing pathway into the evolved strain, its productivity successfully increased to 142% of the control strain.Conclusions
Novel mutations were identified that improved the stress tolerance ability of various alcohols in Synechocystis sp. PCC 6803.12.
Tianzhen Li Wei Zhou Huiping Bi Yibin Zhuang Tongcun Zhang Tao Liu 《Biotechnology letters》2018,40(7):1057-1065
Objectives
To achieve biosynthesis of caffeoylmalic acid from glucose in engineered Escherichia coli.Results
We constructed the biosynthetic pathway of caffeoylmalic acid in E. coli by co-expression of heterologous genes RgTAL, HpaBC, At4CL2 and HCT2. To enhance the production of caffeoylmalic acid, we optimized the tyrosine metabolic pathway of E. coli to increase the supply of the substrate caffeic acid. Consequently, an E. coli–E. coli co-culture system was used for the efficient production of caffeoylmalic acid. The final titer of caffeoylmalic acid reached 570.1 mg/L.Conclusions
Microbial production of caffeoylmalic acid using glucose has application potential. In addition, microbial co-culture is an efficient tool for producing caffeic acid esters.13.
Thijs Welle Anna T. Hoekstra Ineke A. J. J. M. Daemen Celia R. Berkers Matheus O. Costa 《Metabolomics : Official journal of the Metabolomic Society》2017,13(7):83
Introduction
Swine dysentery caused by Brachyspira hyodysenteriae is a production limiting disease in pig farming. Currently antimicrobial therapy is the only treatment and control method available.Objective
The aim of this study was to characterize the metabolic response of porcine colon explants to infection by B. hyodysenteriae.Methods
Porcine colon explants exposed to B. hyodysenteriae were analyzed for histopathological, metabolic and pro-inflammatory gene expression changes.Results
Significant epithelial necrosis, increased levels of l-citrulline and IL-1α were observed on explants infected with B. hyodysenteriae.Conclusions
The spirochete induces necrosis in vitro likely through an inflammatory process mediated by IL-1α and NO.14.
Yu Zhang Ying Wang Mingdong Yao Hong Liu Xiao Zhou Wenhai Xiao Yingjin Yuan 《Biotechnology letters》2017,39(7):1033-1039
Objectives
To engineer Yarrowia lipolytica for improving the heterologous production of campesterol (a key precursor to manufacture pharmaceutical steroids).Results
By screening 7-dehydrocholesterol reductase (DHCR7) from diverse species, DHCR7 from Danio rerio was the best candidate for campesterol synthesis. Overexpression of ACL (ATP: citrate lyase) or POX2 (peroxisome acyl-CoA oxidase 2) were key to improving campesterol production. The highest yield of campesterol was 942 mg/l was with the strain overexpressing POX2 in a 5 l bioreactor via high cell density fermentation process with a restricted supply of carbon sourc, sunflower seed oil.Conclusions
A promising platform to synthesize downstream steroid drugs was established. Efficient approaches were provided to improve the production of desired molecules in Y. lipolytica with high oil utilization efficiency.15.
Objective
To explore the glycerol utilization pathway in Corynebacterium glutamicum for succinate production under O2 deprivation.Result
Overexpression of a glycerol facilitator, glycerol dehydrogenase and dihydroxyacetone kinase from Escherichia coli K-12 in C. glutamicum led to recombinant strains NC-3G diverting glycerol utilization towards succinate production under O2 deprivation. Under these conditions, strain NC-3G efficiently consumed glycerol and produced succinate without growth. The recombinant C. glutamicum utilizing glycerol as the sole carbon source showed higher intracellular NADH/NAD+ ratio compare with utilizing glucose. The mass conversion of succinate increased from 0.64 to 0.95. Using an anaerobic fed-batch fermentation process, the final strain produced 38.4 g succinate/l with an average yield of 1.02 g/g.Conclusions
The metabolically-engineered strains showed an efficient succinate production using glycerol as sole carbon source under O2 deprivation.16.
Andrelisse Arruda Viviane Castelo Branco Reis Vinícius Daniel Ferreira Batista Bruno Sahim Daher Luiza Cesca Piva Janice Lisboa De Marco Lidia Maria Pepe de Moraes Fernando Araripe Gonçalves Torres 《Biotechnology letters》2016,38(3):509-517
Objectives
To develop a new vector for constitutive expression in Pichia pastoris based on the endogenous glycolytic PGK1 promoter.Results
P. pastoris plasmids bearing at least 415 bp of PGK1 promoter sequences can be used to drive plasmid integration by addition at this locus without affecting cell growth. Based on this result, a new P. pastoris integrative vector, pPICK2, was constructed bearing some features that facilitate protein production in this yeast: a ~620 bp PGK1 promoter fragment with three options of restriction sites for plasmid linearization prior to yeast transformation: a codon-optimized α-factor secretion signal, a new polylinker, and the kan marker for vector propagation in bacteria and selection of yeast transformants.Conclusions
A new constitutive vector for P. pastoris represents an alternative platform for recombinant protein production and metabolic engineering purposes.17.
Objectives
To develop a versatile Trichoderma reesei (teleomorph Hypocrea jecorina) expression system for the high-purity production of heterologous proteins.Results
The versatile T. reesei expression system is based on xyn1 and xyn2 promoters, A824V transition in XYRI, and a bicomponent carbon source strategy. Red fluorescent protein gene rfp and alkaline endoglucanase EGV gene egv3 from Humicola insolens were used as reporter genes to test our versatile expression systemConclusions
The versatile T. reesei expression system can be applied to produce heterologous proteins with high purity and high yield.18.
Shenghai Wang Mengjie Duan Yalan Liu Sen Fan Xiaoshan Lin Yi Zhang 《Biotechnology letters》2017,39(3):391-396
Objective
To breed Aspergillus oryzae strains with high fructosyltransferase (FTase) activity using intraspecific protoplast fusion via genome-shuffling.Results
A candidate library was developed using UV/LiCl of the conidia of A. oryzae SBB201. By screening for enzyme activity and cell biomass, two mutants (UV-11 and UV-76) were chosen for protoplast fusion and subsequent genome shuffling. After three rounds of genome recombination, a fusion mutant RIII-7 was obtained. Its FTase activity was 180 U g?1, approximately double that of the original strain, and RIII-7 was genetically stable. In fermentation culture, FTase activity of the genome-shuffled strain reached a maximum of 353 U g?1 using substrate-feeding method, and this value was approximately 3.4-times higher than that of the original strain A. oryzae SBB201.Conclusions
Intraspecific protoplast fusion of A. oryzae significantly enhanced FTase activity and generated a potentially useful strain for industrial production.19.
Yibin Zhuang Jingjie Jiang Huiping Bi Hua Yin Shaowei Liu Tao Liu 《Biotechnology letters》2016,38(4):619-627
Objectives
To produce rosmarinic acid analogues in the recombinant Escherichia coli BLRA1, harboring a 4-coumarate: CoA ligase from Arabidopsis thaliana (At4CL) and a rosmarinic acid synthase from Coleus blumei (CbRAS).Results
Incubation of the recombinant E. coli strain BLRA1 with exogenously supplied phenyllactic acid (PL) and analogues as acceptor substrates, and coumaric acid and analogues as donor substrates led to production of 18 compounds, including 13 unnatural RA analogues.Conclusion
This work demonstrates the viability of synthesizing a broad range of rosmarinic acid analogues in E. coli, and sheds new light on the substrate specificity of CbRAS.20.
Takuya Katayama Yuki Tanaka Tomoya Okabe Hidetoshi Nakamura Wataru Fujii Katsuhiko Kitamoto Jun-ichi Maruyama 《Biotechnology letters》2016,38(4):637-642