Read by QxMD icon Read


Cees Haringa, Wenjun Tang, Amit T Deshmukh, Jianye Xia, Matthias Reuss, Joseph J Heijnen, Robert F Mudde, Henk J Noorman
The trajectories, referred to as lifelines, of individual microorganisms in an industrial scale fermentor under substrate limiting conditions were studied using an Euler-Lagrange computational fluid dynamics approach. The metabolic response to substrate concentration variations along these lifelines provides deep insight in the dynamic environment inside a large-scale fermentor, from the point of view of the microorganisms themselves. We present a novel methodology to evaluate this metabolic response, based on transitions between metabolic "regimes" that can provide a comprehensive statistical insight in the environmental fluctuations experienced by microorganisms inside an industrial bioreactor...
October 2016: Engineering in Life Sciences
Yihong Lu, Cheng Fang, Qinhong Wang, Yuling Zhou, Guimin Zhang, Yanhe Ma
In paper industry, xylanases are used to increase the pulp properties in bleaching process as its eco-friendly nature. The xylanases activity is hindered by high temperature and alkaline conditions with high enzyme production cost in the paper industry. Here, XynHB, an alkaline stable xylanase from Bacillus pumilus HBP8 was mutated at N188A to XynHBN188A. Expressed mutant in E. coli showed 1.5-fold higher xylanase activity than XynHB at 60 °C. The mutant expressed in Pichia pastoris was glycosylated, remained stable for 30 min at 60 °C...
November 29, 2016: Scientific Reports
Dongming Xie, Edward Miller, Pamela Sharpe, Ethel Jackson, Quinn Zhu
The omega-3 fatty acid, cis-5,8,11,14,17-eicosapentaenoic acid (C20:5; EPA) has wide-ranging benefits in improving heart health, immune function, and mental health. A sustainable source of EPA production through fermentation of metabolically engineered Yarrowia lipolytica has been developed. In this paper, key fed-batch fermentation conditions were identified to achieve 25% EPA in the yeast biomass, which is so far the highest EPA titer reported in the literature. Dynamic models of the EPA fermentation process were established for analyzing, optimizing, and scaling up the fermentation process...
November 14, 2016: Biotechnology and Bioengineering
Sofía García, Noemí Flores, Ramón De Anda, Georgina Hernández, Guillermo Gosset, Francisco Bolívar, Adelfo Escalante
The culture of engineered Escherichia coli for shikimic acid (SA) production results in the synthesis of quinic acid (QA) and dehydroshikimic acid (DHS), reducing SA yield and impairing downstream processes. The synthesis of QA by quinate/shikimate dehydrogenase (YdiB, ydiB) has been previously proposed; however, the precise role for this enzyme in the production of QA in engineered strains of E. coli for SA production remains unclear. We report the effect of the inactivation or the overexpression of ydiB in E...
November 18, 2016: Journal of Molecular Microbiology and Biotechnology
Chae Hun Ra, Min Ji Kim, Gwi-Taek Jeong, Sung-Koo Kim
A total monosaccharide concentration of 37.8 g/L and 85.9% conversion from total fermentable monosaccharides of 44.0 g/L from 110 g dw/L Eucheuma denticulatum slurry were obtained by thermal acid hydrolysis and enzymatic saccharification. Subsequent adsorption treatment to remove 5-hydroxymethylfurfural (5-HMF) using 5% activated carbon and an adsorption time of 10 min were used to prevent a prolonged lag phase, reduced cell growth, and low ethanol production. The equilibrium adsorption capacity (q e) of HMF (58...
November 9, 2016: Bioprocess and Biosystems Engineering
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
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"