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Microbial Cell Factories

Anna Detman, Damian Mielecki, Aleksandra Chojnacka, Agnieszka Salamon, Mieczysław K Błaszczyk, Anna Sikora
BACKGROUND: Interactions between microorganisms during specific steps of anaerobic digestion determine metabolic pathways in bioreactors and consequently the efficiency of fermentation processes. This study focuses on conversion of lactate and acetate to butyrate by bacteria of dark fermentation. The recently recognized flavin-based electron bifurcation as a mode of energy coupling by anaerobes increases our knowledge of anaerobic lactate oxidation and butyrate formation. RESULTS: Microbial communities from dark fermentation bioreactors or pure culture of Clostridium butyricum are able to convert lactate and acetate to butyrate in batch experiments...
February 13, 2019: Microbial Cell Factories
Garrett W Roell, Jian Zha, Rhiannon R Carr, Mattheos A Koffas, Stephen S Fong, Yinjie J Tang
During microbial applications, metabolic burdens can lead to a significant drop in cell performance. Novel synthetic biology tools or multi-step bioprocessing (e.g., fermentation followed by chemical conversions) are therefore needed to avoid compromised biochemical productivity from over-burdened cells. A possible solution to address metabolic burden is Division of Labor (DoL) via natural and synthetic microbial consortia. In particular, consolidated bioprocesses and metabolic cooperation for detoxification or cross feeding (e...
February 8, 2019: Microbial Cell Factories
Yingpeng Xu, Li Yang, Shujuan Zhao, Zhengtao Wang
BACKGROUND: Bear bile powder is a valuable medicinal material characterized by high content of tauroursodeoxycholic acid (TUDCA) at a certain ratio to taurochenodeoxycholic acid (TCDCA). We had created an engineered E. coli harboring two-step bidirectional oxidative and reductive enzyme-catalyzing pathway that could rapidly convert TCDCA to TUDCA at a specific percentage in shake flasks. RESULTS: We reported here the large-scale production of TUDCA containing products by balancing the bidirectional reactions through optimizing fermentation process of the engineered E...
February 8, 2019: Microbial Cell Factories
Huan Yu, Ning Wang, Wenbo Huo, Yuhong Zhang, Wei Zhang, Yu Yang, Zhenya Chen, Yi-Xin Huo
BACKGROUND: Isobutanol, a C4 branched-chain higher alcohol, is regarded as an attractive next-generation transport fuel. Metabolic engineering for efficient isobutanol production has been achieved in many studies. BmoR, an alcohol-regulated transcription factor, mediates a σ54 -dependent promoter Pbmo of alkane monooxygenase in n-alkane metabolism of Thauera butanivorans and displays high sensitivity to C4-C6 linear alcohols and C3-C5 branched-chain alcohols. In this study, to achieve the high-level production of isobutanol, we established a screening system which relied on the combination of BmoR-based biosensor and isobutanol biosynthetic pathway and then employed it to screen isobutanol overproduction strains from an ARTP mutagenesis library...
February 7, 2019: Microbial Cell Factories
Elke R Duell, Paul M D'Agostino, Nicole Shapiro, Tanja Woyke, Thilo M Fuchs, Tobias A M Gulder
BACKGROUND: Serratia plymuthica WS3236 was selected for whole genome sequencing based on preliminary genetic and chemical screening indicating the presence of multiple natural product pathways. This led to the identification of a putative sodorifen biosynthetic gene cluster (BGC). The natural product sodorifen is a volatile organic compound (VOC) with an unusual polymethylated hydrocarbon bicyclic structure (C16 H26 ) produced by selected strains of S. plymuthica. The BGC encoding sodorifen consists of four genes, two of which (sodA, sodB) are homologs of genes encoding enzymes of the non-mevalonate pathway and are thought to enhance the amounts of available farnesyl pyrophosphate (FPP), the precursor of sodorifen...
February 7, 2019: Microbial Cell Factories
Outi L Lyytinen, Daria Starkova, Minna M Poranen
BACKGROUND: Cystoviruses have a phospholipid envelope around their nucleocapsid. Such a feature is unique among bacterial viruses (i.e., bacteriophages) and the mechanisms of virion envelopment within a bacterial host are largely unknown. The cystovirus Pseudomonas phage phi6 has an envelope that harbors five viral membrane proteins and phospholipids derived from the cytoplasmic membrane of its Gram-negative host. The phi6 major envelope protein P9 and the non-structural protein P12 are essential for the envelopment of its virions...
February 7, 2019: Microbial Cell Factories
Janine Heinrich, Chris Drewniok, Eva Neugebauer, Harald Kellner, Thomas Wiegert
BACKGROUND: Heterologous gene expression is well established for various prokaryotic model systems. However, low yield, incorrect folding and instability still impede the production of soluble, bioactive proteins. To improve protein production with the Gram-positive host Bacillus subtilis, a secretory expression system was designed that enhances translocation, folding and stability of heterologous proteins, and simplifies purification. Based on the theta-replication plasmid pHT01, a B...
February 7, 2019: Microbial Cell Factories
V D Jäger, R Kloss, A Grünberger, S Seide, D Hahn, T Karmainski, M Piqueray, J Embruch, S Longerich, U Mackfeld, K-E Jaeger, W Wiechert, M Pohl, U Krauss
BACKGROUND: Immobilization is an appropriate tool to ease the handling and recycling of enzymes in biocatalytic processes and to increase their stability. Most of the established immobilization methods require case-to-case optimization, which is laborious and time-consuming. Often, (chromatographic) enzyme purification is required and stable immobilization usually includes additional cross-linking or adsorption steps. We have previously shown in a few case studies that the molecular biological fusion of an aggregation-inducing tag to a target protein induces the intracellular formation of protein aggregates, so called inclusion bodies (IBs), which to a certain degree retain their (catalytic) function...
February 7, 2019: Microbial Cell Factories
Zhenyu Tong, Xiaomei Zheng, Yi Tong, Yong-Cheng Shi, Jibin Sun
Citric acid is the world's largest consumed organic acid and is widely used in beverage, food and pharmaceutical industries. Aspergillus niger is the main industrial workhorse for citric acid production. Since the release of the genome sequence, extensive multi-omic data are being rapidly obtained, which greatly boost our understanding of the citric acid accumulation mechanism in A. niger to a molecular and system level. Most recently, the rapid development of CRISPR/Cas9 system facilitates highly efficient genome-scale genetic perturbation in A...
February 4, 2019: Microbial Cell Factories
Yi-Min Li, Jiao-Qi Gao, Xu-Ze Pei, Cong Du, Chao Fan, Wen-Jie Yuan, Feng-Wu Bai
BACKGROUND: L-Alanyl-L-glutamine (Ala-Gln) represents the great application potential in clinic due to the unique physicochemical properties. A new approach was developed to synthesize Ala-Gln by recombinant Escherichia coli OPA, which could overcome the disadvantages of traditional chemical synthesis. Although satisfactory results had been obtained with recombinant E. coli OPA, endotoxin and the use of multiple antibiotics along with toxic inducer brought the potential biosafety hazard for the clinical application of Ala-Gln...
February 2, 2019: Microbial Cell Factories
Juan Carlos Fragoso-Jiménez, Jonathan Baert, Thai Minh Nguyen, Wenzheng Liu, Hosni Sassi, Frédéric Goormaghtigh, Laurence Van Melderen, Paul Gaytán, Georgina Hernández-Chávez, Alfredo Martinez, Frank Delvigne, Guillermo Gosset
BACKGROUND: Escherichia coli W3110 and a group of six isogenic derivatives, each displaying distinct specific rates of glucose consumption were characterized to determine levels of GFP production and population heterogeneity. These strains have single or combinatory deletions in genes encoding phosphoenolpyruvate:sugar phosphotransferase system (PTS) permeases as PtsG and ManX, as well as common components EI, Hpr protein and EIIA, also the non-PTS Mgl galactose/glucose ABC transporter...
February 2, 2019: Microbial Cell Factories
Yan Hua, Jichao Wang, Yelin Zhu, Biao Zhang, Xin Kong, Wenjie Li, Dongmei Wang, Jiong Hong
BACKGROUND: Lignocellulosic biomass is one of the most abundant materials for biochemicals production. However, efficient co-utilization of glucose and xylose from the lignocellulosic biomass is a challenge due to the glucose repression in microorganisms. Kluyveromyces marxianus is a thermotolerant and efficient xylose-utilizing yeast. To realize the glucose-xylose co-utilization, analyzing the glucose repression of xylose utilization in K. marxianus is necessary. In addition, a glucose-xylose co-utilization platform strain will facilitate the construction of lignocellulosic biomass-utilizing strains...
February 1, 2019: Microbial Cell Factories
Alexandra Bergman, John Hellgren, Thomas Moritz, Verena Siewers, Jens Nielsen, Yun Chen
INTRODUCTION: Phosphoketolases (Xfpk) are a non-native group of enzymes in yeast, which can be expressed in combination with other metabolic enzymes to positively influence the yield of acetyl-CoA derived products by reducing carbon losses in the form of CO2 . In this study, a yeast strain expressing Xfpk from Bifidobacterium breve, which was previously found to have a growth defect and to increase acetate production, was characterized. RESULTS: Xfpk-expression was found to increase respiration and reduce biomass yield during glucose consumption in batch and chemostat cultivations...
February 1, 2019: Microbial Cell Factories
Juan Rico, Katia Duquesne, Jean-Louis Petit, Aline Mariage, Ekaterina Darii, Frédéric Peruch, Véronique de Berardinis, Gilles Iacazio
BACKGROUND: Terpenes are industrially relevant natural compounds the biosynthesis of which relies on two well-established-mevalonic acid (MVA) and methyl erythritol phosphate (MEP)-pathways. Both pathways are widely distributed in all domains of life, the former is predominantly found in eukaryotes and archaea and the latter in eubacteria and chloroplasts. These two pathways supply isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), the universal building blocks of terpenes...
February 1, 2019: Microbial Cell Factories
Wenqian Wang, Yuxin Song, Linlin Liu, Yuan Zhang, Tingting Wang, Wang Zhang, Kai Li, Xiaole Qi, Yulong Gao, Li Gao, Changjun Liu, Yanping Zhang, Yongqiang Wang, Qing Pan, Gaoming He, Xiaomei Wang, Hongyu Cui
BACKGROUND: Infectious bursal disease (IBD) is an acute contagious immunosuppressive disease which lead to acute bursal injury and immune dysfunction in poultry. It has caused heavy economic losses in the commercial poultry industry for many years in worldwide. Attenuated live vaccine has widely used in poultry showing some promising signs against IBDV infection. But it has defects such as generating enhanced virulence and immunosuppression prohibits. Therefore, the development of mucosal vaccines using the food-grade lactic acid bacterium is necessary...
January 31, 2019: Microbial Cell Factories
Tingting Guo, Yongping Xin, Yi Zhang, Xinyi Gu, Jian Kong
BACKGROUND: Lactococcus lactis is one of the most extensively characterized lactic acid bacteria, from physiological traits to industrial exploitation. Since last decade, L. lactis has been developed into cell factories for the production of bioactive compounds such as enzymes, vaccine antigens and natural products. However, its precise and efficient genome editing tools is still required to make L. lactis more suitable candidate for engineered functionality. RESULTS: A high active recombinase, RecT of Enterococcus faecalis ATCC14506, was selected from six candidates and mediated homologous recombination between single-stranded DNA (ssDNA) and the L...
January 31, 2019: Microbial Cell Factories
Xiaomeng Tong, Eun Kyoung Oh, Byeong-Ha Lee, Jeong K Lee
BACKGROUND: Long-chain free fatty acids (FFAs) are a type of backbone molecule that can react with alcohol to produce biodiesels. Various microorganisms have become potent producers of FFAs. Efforts have focused on increasing metabolic flux to the synthesis of either neutral fat or fatty acyl intermediates attached to acyl carrier protein (ACP), which are the source of FFAs. Membrane lipids are also a source of FFAs. As an alternative way of producing FFAs, exogenous phospholipase may be used after heterologous production and localization in the periplasmic space...
January 31, 2019: Microbial Cell Factories
Isabel Guerrero Montero, Katarzyna Magdalena Dolata, Rabea Schlüter, Gilles Malherbe, Susanne Sievers, Daniela Zühlke, Thomas Sura, Emma Dave, Katharina Riedel, Colin Robinson
BACKGROUND: The Twin-arginine translocation (Tat) pathway of Escherichia coli has great potential for the export of biopharmaceuticals to the periplasm due to its ability to transport folded proteins, and its proofreading mechanism that allows correctly folded proteins to translocate. Coupling the Tat-dependent protein secretion with the formation of disulfide bonds in the cytoplasm of E. coli CyDisCo provides a powerful platform for the production of industrially challenging proteins...
January 29, 2019: Microbial Cell Factories
Shuai Qian, Ye Li, Patrick C Cirino
BACKGROUND: Salicylate can be biosynthesized from the common metabolic intermediate shikimate and has found applications in pharmaceuticals and in the bioplastics industry. While much metabolic engineering work focused on the shikimate pathway has led to the biosynthesis of a variety of aromatic compounds, little is known about how the relative expression levels of pathway components influence salicylate biosynthesis. Furthermore, some host strain gene deletions that improve salicylate production may be impossible to predict...
January 29, 2019: Microbial Cell Factories
Qing-Ting Bu, Pin Yu, Jue Wang, Zi-Yue Li, Xin-Ai Chen, Xu-Ming Mao, Yong-Quan Li
BACKGROUND: Streptomyces chattanoogensis L10 is the industrial producer of natamycin and has been proved a highly efficient host for diverse natural products. It has an enormous potential to be developed as a versatile cell factory for production of heterologous secondary metabolites. Here we developed a genome-reduced industrial Streptomyces chassis by rational 'design-build-test' pipeline. RESULTS: To identify candidate large non-essential genomic regions accurately and design large deletion rationally, we performed genome analyses of S...
January 28, 2019: Microbial Cell Factories
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