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Baisuo Zhao, Jie Liu, Craig Frear, Mark Holtzapple, Shulin Chen
This study employed mixed-culture consolidated bioprocessing (CBP) to digest microalgal biomass in an anaerobic sequencing batch reactor (ASBR). The primary objectives are to evaluate the impact of hydraulic residence time (HRT) on the productivity of carboxylic acids and to characterize the bacterial community. HRT affects the production rate and patterns of carboxylic acids. For the 5-L laboratory-scale fermentation, a 12-day HRT was selected because it offered the highest productivity of carboxylic acids and it synthesized longer chains...
October 1, 2016: Bioresource Technology
Song Jiao, Xu Li, Huimin Yu, Huan Yang, Xue Li, Zhongyao Shen
Surfactin-family lipopeptides are green biosurfactants with substantial industrial potential. The major problem prohibiting surfactin use is the low titer of the wild producer, Bacillus subtilis. Using transcriptomic analysis, four strong promoters, PgroE, Pcdd, PrplK, and PsspE, were identified and cloned from the genome of B. subtilis THY-7, a novel surfactin producer that has been identified from soil with a 0.55 g/L surfactin titer. An optimal promoter, PgroE, was selected to replace the native THY-7 surfactin synthase (SrfA) promoter through single-cross homologous recombination; however, the resulting engineered strain containing the PgroE substitution did not synthesize surfactin...
October 10, 2016: Biotechnology and Bioengineering
Lei Yan, Peng Chen, Shuang Zhang, Suyue Li, Xiaojuan Yan, Ningbo Wang, Ning Liang, Hongyu Li
We performed the biotransformation of ferulic acid to vanillin using Bacillus subtilis (B. subtilis) in the stirring packed-bed reactors filled with carbon fiber textiles (CFT). Scanning electron microscope (SEM), HPLC, qRT-PCR and ATP assay indicated that vanillin biotransformation is tightly related to cell growth, cellar activity and the extent of biofilm formation. The biotransformation was affected by hydraulic retention time (HRT), temperature, initial pH, stirring speed and ferulic acid concentration, and the maximum vanillin production was obtained at 20 h, 35 °C, 9...
October 6, 2016: Scientific Reports
Xiaojie Duan, Mingming Zheng, Yu Liu, Zhengqiang Jiang, Shaoqing Yang
OBJECTIVES: To identify novel cold-active lipases from fungal sources and improve their production by heterologous expression in Pichia pastoris. RESULTS: A novel cold-active lipase gene (ReLipB) from Rhizomucor endophyticus was cloned. ReLipB was expressed at a high level in Pichia pastoris using high cell-density fermentation in a 5-l fermentor with the highest lipase activity of 1395 U/ml. The recombinant lipase (RelipB) was purified and biochemically characterized...
September 17, 2016: Biotechnology Letters
Bo Zhang, Zhi-Qiang Liu, Chang Liu, Yu-Guo Zheng
OBJECTIVES: To construct, test and exploit the CRISPRi system for enhancement of shikimic acid production with Corynebacterium glutamicum. RESULTS: The CRISPRi system was used to regulate C. glutamicum gene expression at the transcriptional level. Hfq protein-mediated small regulatory RNAs system was compared with CRISPRi system. The more efficient CRISPRi system was used to adjust the metabolic flux involving the shikimic acid (SA) synthetic pathway. In 11 candidate genes, including transcription regulator, three targets were effective for increasing SA production...
September 13, 2016: Biotechnology Letters
Fei Lu, Chao Li, Zejian Wang, Wei Zhao, Ju Chu, Yingping Zhuang, Siliang Zhang
In this paper, a system of cell-recycle continuous fermentation for sodium gluconate (SG) production by Aspergillus niger (A. niger) was established. Based on initial continuous fermentation result (100.0h) with constant feed rate, an automatic feedback strategy to regulate feed rate using on-line physiological parameters (OUR and DO) was proposed and applied successfully for the first time in the improved continuous fermentation (240.5h). Due to less auxiliary time, highest SG production rate (31.05±0.29gL(-1)h(-1)) and highest yield (0...
November 2016: Bioresource Technology
Dongqin Ding, Yongfei Liu, Yiran Xu, Ping Zheng, Haixing Li, Dawei Zhang, Jibin Sun
L-Phenylalanine (L-Phe) is an important amino acid used in both food and medicinal applications. We developed an in vitro system that allowed a direct, quantitative investigation of phenylalanine biosynthesis in E. coli. Here, the absolute concentrations of six enzymes (AroK, AroL, AroA, AroC, PheA and TyrB) involved in the shikimate (SHIK) pathway were determined by a quantitative proteomics approach and in vitro enzyme titration experiments. The reconstitution of an in vitro reaction system for these six enzymes was established and their effects on the phenylalanine production were tested...
2016: Scientific Reports
Yongkang Wang, Xiaodan Song, Yongjun Zhang, Bochu Wang, Xiang Zou
BACKGROUND: Polymalic acid (PMA) is a novel polyester polymer that has been broadly used in the medical and food industries. Its monomer, L-malic acid, is also a potential C4 platform chemical. However, little is known about the mechanism of PMA biosynthesis in the yeast-like fungus, Aureobasidium pullulans. In this study, the effects of different nitrogen concentration on cell growth and PMA biosynthesis were investigated via comparative transcriptomics and proteomics analyses, and a related signaling pathway was also evaluated...
2016: Microbial Cell Factories
Jingqi Chen, Yueming Zhu, Gang Fu, Yafeng Song, Zhaoxia Jin, Yuanxia Sun, Dawei Zhang
D-Psicose 3-epimerase (DPEase) converts D-fructose into D-psicose which exists in nature in limited quantities and has key physiological functions. In this study, RDPE (DPEase from Ruminococcus sp. 5_1_39BFAA) was successfully constitutively expressed in Bacillus subtilis, which is the first report of its kind. Three sugar-inducible promoters were compared, and the xylose-inducible promoter P xylA was proved to be the most efficient for RDPE production. Based on the analysis of the inducer concentration and RDPE expression, we surmised that there was an extremely close correlation between the intracellular RDPE expression and xylose accumulation level...
November 2016: Journal of Industrial Microbiology & Biotechnology
Bo Guan, Fengxiang Chen, Shuai Su, Zuoying Duan, Yun Chen, Huazhong Li, Jian Jin
Pichia pastoris is generally considered as an expression host for heterologous proteins with the coding gene under control of the alcohol oxidase 1 (AOX1) promoter. The secretion of heterologous proteins in P. pastoris can be potentially affected by many factors. Based on our previous results, the secretion levels of human albumin (HSA) fusion protein IL2-HSA were only around 500 mg/L or less in fermentor cultures, which decreased more than 50% comparing to that of HSA (>1 g/L). In this study, we selected five potential secretion helper factors, in which Ero1, Pdi1 and Kar2 involved in protein folding and Sec1 and Sly1 involved in vesicle trafficking...
August 17, 2016: Yeast
Qiaoqiao Sun, Hui Wang, Huitu Zhang, Huiying Luo, Pengjun Shi, Yingguo Bai, Fuping Lu, Bin Yao, Huoqing Huang
Thermophilic Neosartorya fischeri P1 is an excellent lipase producer and harbors seven lipase genes. All genes were found to be functional after heterologous expression in Escherichia coli. One of them, LIP09, showed high-level expression in Pichia pastoris with the yield of 2.0 g/L in a 3.7-L fermentor. Deduced amino acid sequence of LIP09 consists of a putative signal peptide (residues 1-19) and a mature polypeptide (residues 20-562). Compared with other fungal counterparts, purified recombinant LIP09 has some superior properties...
August 5, 2016: Journal of Bioscience and Bioengineering
Luan Luong Chu, Ramesh Prasad Pandey, Narae Jung, Hye Jin Jung, Eun-Hee Kim, Jae Kyung Sohng
BACKGROUND: Cytochrome P450 monooxygenase constitutes a significant group of oxidative enzymes that can introduce an oxygen atom in a high regio- and stereo-selectivity mode. We used the Bacillus megaterium cytochrome P450 BM3 (CYP450 BM3) and its variants namely mutant 13 (M13) and mutant 15 (M15) for the hydroxylation of diverse class of flavonoids. RESULTS: Among 20 flavonoids, maximum seven flavonoids were hydroxylated by the variants while none of these molecules were accepted by CYP450 BM3 in in vitro reaction...
2016: Microbial Cell Factories
Chuang Xue, Fangfang Liu, Mengmeng Xu, I-Ching Tang, Jingbo Zhao, Fengwu Bai, Shang-Tian Yang
Activated carbon Norit ROW 0.8, zeolite CBV901, and polymeric resins Dowex Optipore L-493 and SD-2 with high specific loadings and partition coefficients were studied for n-butanol adsorption. Adsorption isotherms were found to follow Langmuir model, which can be used to estimate the amount of butanol adsorbed in acetone-butanol-ethanol (ABE) fermentation. In serum-bottle fermentation with in situ adsorption, activated carbon showed the best performance with 21.9g/L of butanol production. When operated in a fermentor, free- and immobilized-cell fermentations with adsorption produced 31...
November 2016: Bioresource Technology
Panyu Li, Ting Li, Yu Zeng, Xiang Li, Xiaolong Jiang, Yabo Wang, Tonghui Xie, Yongkui Zhang
Herein, we report the production of xanthan gum by fermentation using kitchen waste as the sole substrate. The kitchen waste was firstly pretreated by a simple hydrolysis method, after which the obtained kitchen waste hydrolysate was diluted with an optimal ratio 1:2. In a 5-L fermentor, the maximum xanthan production, reducing sugar conversion and utilization rates reached 11.73g/L, 67.07% and 94.82%, respectively. The kinetics of batch fermentation was also investigated. FT-IR and XRD characterizations confirmed the fermentation product as xanthan gum...
October 20, 2016: Carbohydrate Polymers
Meng Liu, Xu Zhang, Tianwei Tan
In this paper, the components of amino acids in mixed starch wastewater (corn steep water/corn gluten water=1/3, v/v) were analyzed by GC-MS. Effects of amino acids on lipid production by Rhodotorula glutinis and COD removal were studied. The results showed that mixed starch wastewater contained 9 kinds of amino acids and these amino acids significantly improved the biomass (13.63g/L), lipid yield (2.48g/L) and COD removal compared to the basic medium (6.23g/L and 1.56g/L). In a 5L fermentor containing mixed starch wastewater as substrate to culture R...
October 2016: Bioresource Technology
Jian Guo, Junxia Li, Yefu Chen, Xuewu Guo, Dongguang Xiao
The biotransformation of xylose, the second most abundant sugar, has been a hot topic in recent years. In this work, Aureobasidium pullulans CGMCC3.0837 was subjected to UV mutagenesis to improve its erythritol production from xylose. The erythritol production of the obtained mutant ER35 was 50.92 % (17.28 g/L) higher than that of the parent strain. Response surface methodology was applied to optimize the medium composition. Yeast extract, KH2PO4, and citric acid were the key factors influencing erythritol synthesis, and the optimal concentrations were 17...
July 11, 2016: Applied Biochemistry and Biotechnology
Kadriye Inan, Fulya Ay Sal, Asif Rahman, Ryan J Putman, Foster A Agblevor, Charles D Miller
BACKGROUND: One of the potential limitations of large scale aerobic Escherichia coli fermentation is the need for increased dissolved oxygen for culture growth and bioproduct generation. As culture density increases the poor solubility of oxygen in water becomes one of the limiting factors for cell growth and product formation. A potential solution is to use a microbubble dispersion (MBD) generating device to reduce the diameter and increase the surface area of sparged bubbles in the fermentor...
2016: BMC Research Notes
Sarn Settachaimongkon, Hein J F van Valenberg, Inge Gazi, M J Robert Nout, Toon C M van Hooijdonk, Marcel H Zwietering, Eddy J Smid
The objectives of this study were to evaluate the growth and survival of the model probiotic strain Lactobacillus plantarum WCFS1 in co-culture with traditional yoghurt starters and to investigate the impact of preculturing on their survival and metabolite formation in set-yoghurt. L. plantarum WCFS1 was precultured under sublethal stress conditions (combinations of elevated NaCl and low pH) in a batch fermentor before inoculation in milk. Adaptive responses of L. plantarum WCFS1 were evaluated by monitoring bacterial population dynamics, milk acidification and changes in volatile and non-volatile metabolite profiles of set-yoghurt...
October 2016: Food Microbiology
Junjun Wu, Xia Zhang, Mingsheng Dong, Jingwen Zhou
Developing efficient microbial processes to produce flavonoids has been a metabolic engineering goal over the past decade due to their important functions. Previously, the de novo production of the main flavonoid precursor (2S)-pinocembrin was achieved. However, low productivity and two separate fermentation steps made it inappropriate for industrial scale low-cost production. Here, a stepwise modular engineering approach was introduced to systematically identify and eliminate metabolic pathway bottlenecks...
August 10, 2016: Journal of Biotechnology
Jie Feng, Na Feng, Jing-Song Zhang, Yan Yang, Wei Jia, Chi-Chung Lin
Temperature control is a very important factor on triterpene productivity in submerged liquid fermentation. Temperature effects from 23 to 32 °C on triterpene production by Ganoderma lucidum G0119 were investigated in 6-L stirred fermentor. Logistic and Luedeking-Piret equations were used to estimate the mycelial growth and triterpene production kinetics by regression analysis. On that basis, a temperature-shifting fermentation control strategy was established. From 0 to 61 h, culturing was performed at 32 °C to get high specific mycelial growth rate...
June 6, 2016: Applied Biochemistry and Biotechnology
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