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Microbial Cell Factories

Ting Liu, Chuanbo Zhang, Wenyu Lu
BACKGROUND: Levopimaric acid (LA), a type of diterpene resin acid produced by plants, is a significant industrial intermediate that is mainly produced via phytoextraction. This work aimed to apply synthetic biology to produce LA in yeast strains from a simple carbon source. RESULTS: Levopimaradiene (LP), the precursor of LA, was produced via LP synthase (LPS) expression in yeast. LPS was then modified by N-terminal truncating and site-directed mutagenesis. The strain containing t79LPSMM (79 N-terminal amino acid truncating and M593I/Y700F mutation) produced 6...
July 18, 2018: Microbial Cell Factories
Debora Trichez, Clément Auriol, Audrey Baylac, Romain Irague, Clémentine Dressaire, Marc Carnicer-Heras, Stéphanie Heux, Jean Marie François, Thomas Walther
BACKGROUND: Malate is a C4-dicarboxylic acid widely used as an acidulant in the food and beverage industry. Rational engineering has been performed in the past for the development of microbial strains capable of efficient production of this metabolite. However, as malate can be a precursor for specialty chemicals, such as 2,4-dihydroxybutyric acid, that require additional cofactors NADP(H) and ATP, we set out to reengineer Escherichia coli for Krebs cycle-dependent production of malic acid that can satisfy these requirements...
July 16, 2018: Microbial Cell Factories
Loknath Gidijala, Stefan Uthoff, Sebastiaan J van Kampen, Alexander Steinbüchel, Raymond M D Verhaert
BACKGROUND: The yeast Komagataella phaffii, better known as Pichia pastoris, is a commonly used host for recombinant protein production. Here expression vectors are reported that address the different steps of the transcription-translation-secretion pathway of heterologous protein production. RESULTS: Transcription and translation enhancing elements were introduced in an expression cassette for the production of recombinant Aspergillus niger feruloyl esterase A...
July 13, 2018: Microbial Cell Factories
Katharina Novak, Lukas Flöckner, Anna Maria Erian, Philipp Freitag, Christoph Herwig, Stefan Pflügl
BACKGROUND: Due to its high stress tolerance and low acetate secretion, Escherichia coli W is reported to be a good production host for several metabolites and recombinant proteins. However, simultaneous co-utilization of glucose and other substrates such as acetate remains a challenge. The activity of acetyl-CoA-synthetase, one of the key enzymes involved in acetate assimilation is tightly regulated on a transcriptional and post-translational level. The aim of this study was to engineer E...
July 9, 2018: Microbial Cell Factories
Teresa Mohr, Habibu Aliyu, Raphael Küchlin, Shamara Polliack, Michaela Zwick, Anke Neumann, Don Cowan, Pieter de Maayer
BACKGROUND: The overreliance on dwindling fossil fuel reserves and the negative climatic effects of using such fuels are driving the development of new clean energy sources. One such alternative source is hydrogen (H2 ), which can be generated from renewable sources. Parageobacillus thermoglucosidasius is a facultative anaerobic thermophilic bacterium which is frequently isolated from high temperature environments including hot springs and compost. RESULTS: Comparative genomics performed in the present study showed that P...
July 9, 2018: Microbial Cell Factories
Janina Müller, Mario Beckers, Nina Mußmann, Johannes Bongaerts, Jochen Büchs
BACKGROUND: Culture media containing complex compounds like yeast extract or peptone show numerous disadvantages. The chemical composition of the complex compounds is prone to significant variations from batch to batch and quality control is difficult. Therefore, the use of chemically defined media receives more and more attention in commercial fermentations. This concept results in better reproducibility, it simplifies downstream processing of secreted products and enable rapid scale-up...
July 9, 2018: Microbial Cell Factories
Katherina Garcia Vanegas, Arésu Bondrup Larsen, Michael Eichenberger, David Fischer, Uffe Hasbro Mortensen, Michael Naesby
BACKGROUND: C-glycosylated flavones have recently attracted increased attention due to their possible benefits in human health. These biologically active compounds are part of the human diet, and the C-linkage makes them more resistant to hydrolysis and degradation than O-glycosides. In contrast to O-glycosyltransferases, few C-glycosyltransferases (CGTs) have so far been characterized. Two different biosynthetic routes for C-glycosylated flavones have been identified in plants. Depending on the type of C-glycosyltransferase, flavones can be glycosylated either directly or indirectly via C-glycosylation of a 2-hydroxyflavanone intermediate formed by a flavanone 2-hydroxylase (F2H)...
July 9, 2018: Microbial Cell Factories
Song Wang, Sujit K Verma, Inamullah Hakeem Said, Laurenz Thomsen, Matthias S Ullrich, Nikolai Kuhnert
BACKGROUND: Marine diatoms have a higher fucoxanthin content in comparison to macroalgae. Fucoxanthin features many potent bioactive properties, particularly anti-obesity properties. Despite the great potential for harvesting larger amounts of fucoxanthin, the impacts of light quality (light source, intensity, and photoperiod) on fucoxanthin production and the essential proteins involved in fucoxanthin biosynthesis in marine diatoms remain unclear. RESULTS: In the present study, Cylindrotheca closterium was selected from four different species of diatoms based on its high fucoxanthin content and productivity...
July 9, 2018: Microbial Cell Factories
Jingya Li, Changhao Li, Christopher Q Lan, Dankui Liao
BACKGROUND: Low concentration NaHCO3 (ca. 12 mM) had been demonstrated to be an excellent carbon source for industrially important green alga Chlorella vulgaris and high concentration NaHCO3 (e.g. 160 mM) had been shown to be capable of controlling protozoa and stimulating lipid accumulation of another green alga, i.e., Neochloris oleoabundans. Furthermore, little was known about the mechanisms of the effects of NaHCO3 on microalgae. Thorough studies on the effects of high NaHCO3 on C...
July 9, 2018: Microbial Cell Factories
Jian-Zhong Xu, Ze-Hua Wu, Shi-Jun Gao, Weiguo Zhang
BACKGROUND: Oxaloacetate (OAA) and L-glutamate are essential precursors for the biosynthesis of L-lysine. Reasonable control of all potentially rate-limiting steps, including the precursors supply rate, is of vital importance to maximize the efficiency of L-lysine fermentation process. RESULTS: In this paper, we have rationally engineered the tricarboxylic acid (TCA) cycle that increased the carbon yield (from 36.18 to 59.65%), final titer (from 14.47 ± 0.41 to 23...
July 7, 2018: Microbial Cell Factories
Oscar van Mastrigt, Diego Gallegos Tejeda, Mette N Kristensen, Tjakko Abee, Eddy J Smid
BACKGROUND: Cheese ripening is a complex, time consuming and expensive process, which involves the generation of precursors from carbohydrates, proteins and fats and their subsequent conversion into a wide range of compounds responsible for the flavour and texture of the cheese. This study aims to investigate production of cheese aroma compounds outside the cheese matrix that could be applied for instance as food supplements in dairy or non-dairy products. RESULTS: In this study, aroma formation by a dairy Lactococcus lactis was analysed as a function of the growth medium [milk, hydrolysed micellar casein isolate (MCI) and chemically defined medium (CDM)] and the cultivation conditions (batch culture, retentostat culture and a milli-cheese model system)...
July 4, 2018: Microbial Cell Factories
Jing Chen, Wei Li, Zhao-Zhou Zhang, Tian-Wei Tan, Zheng-Jun Li
BACKGROUND: High production cost of bioplastics polyhydroxyalkanoates (PHA) is a major obstacle to replace traditional petro-based plastics. To address the challenges, strategies towards upstream metabolic engineering and downstream fermentation optimizations have been continuously pursued. Given that the feedstocks especially carbon sources account up to a large portion of the production cost, it is of great importance to explore low cost substrates to manufacture PHA economically. RESULTS: Escherichia coli was metabolically engineered to synthesize poly-3-hydroxybutyrate (P3HB), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) using acetate as a main carbon source...
July 3, 2018: Microbial Cell Factories
Mark Levisson, Constantinos Patinios, Sascha Hein, Philip A de Groot, Jean-Marc Daran, Robert D Hall, Stefan Martens, Jules Beekwilder
BACKGROUND: Anthocyanins are polyphenolic pigments which provide pink to blue colours in fruits and flowers. There is an increasing demand for anthocyanins, as food colorants and as health-promoting substances. Plant production of anthocyanins is often seasonal and cannot always meet demand due to low productivity and the complexity of the plant extracts. Therefore, a system of on-demand supply is useful. While a number of other (simpler) plant polyphenols have been successfully produced in the yeast Saccharomyces cerevisiae, production of anthocyanins has not yet been reported...
July 3, 2018: Microbial Cell Factories
Sora Yu, Jing-Jing Liu, Eun Ju Yun, Suryang Kwak, Kyoung Heon Kim, Yong-Su Jin
BACKGROUND: 2'-Fucosyllactose (2-FL), one of the most abundant oligosaccharides in human milk, has potential applications in foods due to its health benefits such as the selective promotion of bifidobacterial growth and the inhibition of pathogenic microbial binding to the human gut. Owing to the limited amounts of 2-FL in human milk, alternative microbial production of 2-FL is considered promising. To date, microbial production of 2-FL has been studied mostly in Escherichia coli. In this study, 2-FL was produced alternatively by using a yeast Saccharomyces cerevisiae, which may have advantages over E...
June 27, 2018: Microbial Cell Factories
Alina Świzdor, Anna Panek, Paulina Ostrowska
BACKGROUND: Metabolic activities of microorganisms to modify the chemical structures of organic compounds became an effective tool for the production of high-valued steroidal drugs or their precursors. Currently research efforts in production of steroids of pharmaceutical interest are focused on either optimization of existing processes or identification of novel potentially useful bioconversions. Previous studies demonstrated that P. lanosocoeruleum KCH 3012 metabolizes androstanes to the corresponding lactones with high yield...
June 26, 2018: Microbial Cell Factories
Han Wang, Xiangzhen Li, Yi Wang, Yong Tao, Shaowen Lu, Xiaoyu Zhu, Daping Li
BACKGROUND: Global energy and resource shortages make it necessary to quest for renewable resources. n-Caproic acid (CA) production based on carboxylate platform by anaerobic fermentation is booming. Recently, a novel Ruminococcaceae bacterium CPB6 is shown to be a potential biotransformation factory for CA production from lactate-containing wastewater. However, little is known about the effects of different electron acceptors (EAs) on the fermentative products of strain CPB6, as well as the optimum medium for CA production...
June 25, 2018: Microbial Cell Factories
Tingting Yao, Zengzhi Liu, Tong Li, Hui Zhang, Jing Liu, Huayue Li, Qian Che, Tianjiao Zhu, Dehai Li, Wenli Li
BACKGROUND: Polyene antibiotics are important as antifungal medicines albeit with serious side effects such as nephrotoxicity. Reedsmycin (RDM) A (1), produced by marine-derived Streptomyces youssoufiensis OUC6819, is a non-glycosylated polyene macrolide antibiotic with antifungal activity comparable to that of clinically used nystatin. To elucidate its biosynthetic machinery, herein, the rdm biosynthetic gene cluster was cloned and characterized. RESULTS: The rdm cluster is located within a 104 kb DNA region harboring 21 open reading frames (ORFs), among which 15 ORFs were designated as rdm genes...
June 19, 2018: Microbial Cell Factories
Markus R M Fiedler, Lars Barthel, Christin Kubisch, Corrado Nai, Vera Meyer
BACKGROUND: The lifestyle of filamentous fungi depends on the secretion of hydrolytic enzymes into the surrounding medium, which degrade polymeric substances into monomers that are then taken up to sustain metabolism. This feature has been exploited in biotechnology to establish platform strains with high secretory capacity including Aspergillus niger. The accepted paradigm is that proteins become mainly secreted at the tips of fungal hyphae. However, it is still a matter of debate if the amount of growing hyphal tips in filamentous fungi correlates with an increase in secretion, with previous studies showing either a positive or no correlation...
June 16, 2018: Microbial Cell Factories
Benjamin Roenneke, Natalie Rosenfeldt, Sami M Derya, Jens F Novak, Kay Marin, Reinhard Krämer, Gerd M Seibold
BACKGROUND: α-D-Glucosylglycerol (αGG) has beneficial functions as a moisturizing agent in cosmetics and potential as a health food material, and therapeutic agent. αGG serves as compatible solute in various halotolerant cyanobacteria such as Synechocystis sp. PCC 6803, which synthesizes αGG in a two-step reaction: The enzymatic condensation of ADP-glucose and glycerol 3-phosphate by GG-phosphate synthase (GGPS) is followed by the dephosphorylation of the intermediate by the GG-phosphate phosphatase (GGPP)...
June 16, 2018: Microbial Cell Factories
Liangcai Lin, Zhiyong Sun, Jingen Li, Yong Chen, Qian Liu, Wenliang Sun, Chaoguang Tian
BACKGROUND: The cellulolytic fungus Neurospora crassa is considered a potential host for enzyme and bioethanol production. However, large scale applications are hindered by its filamentous growth. Although previous investigations have shown that mycelial morphology in submerged culture can be controlled by altering physical factors, there is little knowledge available about the potential for morphology control by genetic modification. RESULTS: In this study, we screened morphological mutants in the filamentous fungus N...
June 16, 2018: Microbial Cell Factories
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