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https://www.readbyqxmd.com/read/28646084/a-novel-mechanism-linked-to-cell-density-largely-controls-cell-division-in-synechocystis
#1
Alberto A Esteves-Ferreira, Masami Inaba, Toshihiro Obata, Antoine Fort, Gerard Fleming, Wagner L Araújo, Alisdair R Fernie, Ronan Sulpice
Many studies have investigated the various genetic and environmental factors regulating cyanobacterial growth. Here, we investigated the growth and metabolism of Synechocystis sp. PCC 6803, under different nitrogen sources, light intensities and CO2 concentrations. Cells grown on urea showed the highest growth rates. However, for all the conditions, the daily growth rates in batch cultures decreased steadily over time, and stationary phase was obtained with similar cell densities. Unexpectedly, metabolic and physiological analyses showed that growth rates during log phase were not primarily controlled by the availability of photoassimilates...
June 23, 2017: Plant Physiology
https://www.readbyqxmd.com/read/28645580/chemostat-studies-of-bacteriophage-m13-infected-escherichia-coli-jm109-for-continuous-ssdna-production
#2
Benjamin Kick, Karl Lorenz Behler, Timm Steffen Severin, Dirk Weuster-Botz
Steady state studies in a chemostat enable the control of microbial growth rate at defined reaction conditions. The effects of bacteriophage M13 infection on maximum growth rate of Escherichia coli JM109 were studied in parallel operated chemostats on a milliliter-scale to analyze the steady state kinetics of phage production. The bacteriophage infection led to a decrease in maximum specific growth rate of 15 % from 0.74 h(-1) to 0.63 h(-1). Under steady state conditions, a constant cell specific ssDNA formation rate of 0...
June 20, 2017: Journal of Biotechnology
https://www.readbyqxmd.com/read/28643181/promoting-acid-resistance-and-nisin-yield-of-lactococcus-lactis-f44-by-genetically-increasing-d-asp-amidation-level-inside-cell-wall
#3
Panlong Hao, Dongmei Liang, Lijie Cao, Bin Qiao, Hao Wu, Qinggele Caiyin, Hongji Zhu, Jianjun Qiao
Nisin fermentation by Lactococcus lactis requires a low pH to maintain a relatively higher nisin activity. However, the acidic environment will result in cell arrest, and eventually decrease the relative nisin production. Hence, constructing an acid-resistant L. lactis is crucial for nisin harvest in acidic nisin fermentation. In this paper, the first discovery of the relationship between D-Asp amidation-associated gene (asnH) and acid resistance was reported. Overexpression of asnH in L. lactis F44 (F44A) resulted in a sevenfold increase in survival capacity during acid shift (pH 3) and enhanced nisin desorption capacity compared to F44 (wild type), which subsequently contributed to higher nisin production, reaching 5346 IU/mL, 57...
June 22, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28641405/biotransformation-of-ferulic-acid-to-protocatechuic-acid-by-corynebacterium-glutamicum-atcc-21420-engineered-to-express-vanillate-o-demethylase
#4
Naoko Okai, Takaya Masuda, Yasunobu Takeshima, Kosei Tanaka, Ken-Ichi Yoshida, Masanori Miyamoto, Chiaki Ogino, Akihiko Kondo
Ferulic acid (4-hydroxy-3-methoxycinnamic acid, FA) is a lignin-derived phenolic compound abundant in plant biomass. The utilization of FA and its conversion to valuable compounds is desired. Protocatechuic acid (3,4-dihydroxybenzoic acid, PCA) is a precursor of polymers and plastics and a constituent of food. A microbial conversion system to produce PCA from FA was developed in this study using a PCA-producing strain of Corynebacterium glutamicum F (ATCC 21420). C. glutamicum strain F grown at 30 °C for 48 h utilized 2 mM each of FA and vanillic acid (4-hydroxy-3-methoxybenzoic acid, VA) to produce PCA, which was secreted into the medium...
December 2017: AMB Express
https://www.readbyqxmd.com/read/28637476/eliminating-acetate-formation-improves-citramalate-production-by-metabolically-engineered-escherichia-coli
#5
Naga Sirisha Parimi, Ian A Durie, Xianghao Wu, Afaq M M Niyas, Mark A Eiteman
BACKGROUND: Citramalate, a chemical precursor to the industrially important methacrylic acid (MAA), can be synthesized using Escherichia coli overexpressing citramalate synthase (cimA gene). Deletion of gltA encoding citrate synthase and leuC encoding 3-isopropylmalate dehydratase were critical to achieving high citramalate yields. Acetate is an undesirable by-product potentially formed from pyruvate and acetyl-CoA, the precursors of citramalate during aerobic growth of E. coli. This study investigated strategies to minimize acetate and maximize citramalate production in E...
June 21, 2017: Microbial Cell Factories
https://www.readbyqxmd.com/read/28637087/deleting-pck-improves-growth-and-suppresses-by-product-formation-during-1-3-propanediol-fermentation-by-klebsiella-pneumoniae
#6
Yongqiang Zhang, Zongxiao Ji, Jie Lin, Danfeng Xu, Shuilin Fu, Heng Gong
AIMS: To investigate the role of phosphoenolpyruvate (PEP) carboxylation in cell metabolism in Klebsiella pneumoniae. METHODS AND RESULTS: The effects of deleting pck, which encodes PEP carboxykinase (PCK), and/or ppc, which encodes PEP carboxylase (PPC), on growth, enzyme activity, and metabolite formation of K. pneumoniae were investigated. A self-regulatory mechanism of PEP carboxylation was found in ppc- or pck-deficient mutants, which resulted in almost no change of succinate formation...
June 21, 2017: Journal of Applied Microbiology
https://www.readbyqxmd.com/read/28635662/development-of-a-dunaliella-tertiolecta-strain-with-increased-zeaxanthin-content-using-random-mutagenesis
#7
Minjae Kim, Junhak Ahn, Hancheol Jeon, EonSeon Jin
Zeaxanthin is a xanthophyll pigment that is regarded as one of the best carotenoids for the prevention and treatment of degenerative diseases. In the worldwide natural products market, consumers prefer pigments that have been produced from biological sources. In this study, a Dunaliella tertiolecta strain that has 10-15% higher cellular zeaxanthin content than the parent strain (zea1), was obtained by random mutagenesis using ethyl methanesulfonate (EMS) as a mutagen. This mutant, mp3, was grown under various salinities and light intensities to optimize culture conditions for zeaxanthin production...
June 21, 2017: Marine Drugs
https://www.readbyqxmd.com/read/28634812/semi-industrial-scale-production-of-a-new-yeast-with-probiotic-traits-cryptococcus-sp-ymhs-isolated-from-the-red-sea
#8
Ashraf F El-Baz, Hesham A El-Enshasy, Yousseria M Shetaia, Hoda Mahrous, Nor Zalina Othman, Ahmed E Yousef
A new yeast strain with promising probiotic traits was isolated from the Red Sea water samples. The isolate (YMHS) was subjected to genetic characterization and identified as Cryptococcus sp. Nucleotide sequence analysis of the rRNA gene internal transcribed spacer regions showed 95% sequence similarity between the isolate and Cryptococcus albidus. Cryptococcus sp. YMHS exhibited desirable characteristics of probiotic microorganisms; it has tolerance to low pH in simulated gastric juice, resistance to bile salts, hydrophobic characteristics, broad antimicrobial activity, and in vitro ability to degrade cholesterol...
June 20, 2017: Probiotics and Antimicrobial Proteins
https://www.readbyqxmd.com/read/28633643/enhancement-of-thermoalkaliphilic-xylanase-production-by-pichia-pastoris-through-novel-fed-batch-strategy-in-high-cell-density-fermentation
#9
Tingting Shang, Dayong Si, Dongyan Zhang, Xuhui Liu, Longmei Zhao, Cong Hu, Yu Fu, Rijun Zhang
BACKGROUND: Xylanase degrades xylan into monomers of various sizes by catalyzing the endohydrolysis of the 1,4-β-D-xylosidic linkage randomly, possessing potential in wide industrial applications. Most of xylanases are susceptible to be inactive when suffering high temperature and high alkaline process. Therefore, it is necessary to develop a high amount of effective thermoalkaliphilic xylanases. This study aims to enhance thermoalkaliphilic xylanase production in Pichia pastoris through fermentation parameters optimization and novel efficient fed-batch strategy in high cell-density fermentation...
June 21, 2017: BMC Biotechnology
https://www.readbyqxmd.com/read/28628989/pollutant-removal-and-microorganism-evolution-of-activated-sludge-under-ofloxacin-selection-pressure
#10
Qiang Kong, Xiao He, Yu Feng, Ming-Sheng Miao, Qian Wang, Yuan-da Du, Fei Xu
An activated sludge sequencing batch reactor (SBR) was fed with synthetic wastewater containing ofloxacin (OFL) for 52days to study the overall performance of the SBR, the characteristics of extracellular polymeric substances (EPS) and the bacterial community shift. Removal efficiencies of chemical oxygen demand, ammonia nitrogen, phosphorus and OFL were maintained at 90%, 96%, 80% and 65%, respectively. The EPS contents increased with increasing OFL concentration because more EPS was secreted to protect cells from OFL damage...
June 14, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28628982/the-physiology-of-trace-elements-in-biological-methane-production
#11
Annalisa Abdel Azim, Christian Pruckner, Philipp Kolar, Ruth-Sophie Taubner, Debora Fino, Guido Saracco, Filipa L Sousa, Simon K-M R Rittmann
Trace element (TE) requirements of Methanothermobacter okinawensis and Methanothermobacter marburgensis were examined in silico, and using closed batch and fed-batch cultivation experiments. In silico analysis revealed genomic differences among the transport systems and enzymes related to the archaeal Wood-Ljungdahl pathway of these two methanogens. M. okinawensis responded to rising concentrations of TE by increasing specific growth rate (µ) and volumetric productivity (MER) during closed batch cultivation, and can grow and produce methane (CH4) during fed-batch cultivation...
June 2, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28627725/proteomic-analysis-of-host-cell-protein-dynamics-in-the-supernatant-of-fc-fusion-protein-producing-cho-dg44-and-dukx-b11-cell-lines-in-batch-and-fed-batch-cultures
#12
Jin Hyoung Park, Jong Hwa Jin, In Jung Ji, Hyun Joo An, Jong Won Kim, Gyun Min Lee
Chinese hamster ovary (CHO) cells are the most widely used host cell lines for the commercial production of therapeutic proteins including Fc-fusion proteins. During the culture of recombinant CHO (rCHO) cells, host cell proteins (HCPs), secreted from viable cells and released from dead cells, accumulate extracellularly, potentially impairing product quality. In this study, the HCPs that accumulated extracellularly in batch and fed-batch cultures of Fc-fusion protein-producing rCHO cell lines (DG-Fc and DUKX-Fc) were identified and quantified using nanoflow liquid chromatography-tandem mass spectrometry (LC-MS/MS), followed by gene ontology and functional analysis...
June 19, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28627711/fermentation-strategy-for-second-generation-ethanol-production-from-sugarcane-bagasse-hydrolyzate-by-spathaspora-passalidarum-and-scheffersomyces-stipitis
#13
S C Nakanishi, L B Soares, L E Biazi, V M Nascimento, A C Costa, G J M Rocha, J L Ienczak
Alcoholic fermentation of released sugars in pretreatment and enzymatic hydrolysis of biomass is a central feature for second generation ethanol (E2G) production. Saccharomyces cerevisiae used industrially in the production of first generation ethanol (E1G) convert sucrose, fructose and glucose into ethanol. However, these yeasts have no ability to ferment pentose (xylose). Therefore, the present work has focused on E2G production by Scheffersomyces stipitis and Spathaspora passalidarum. The fermentation strategy with high pitch, cell recycle, fed-batch mode and temperature decrease for each batch were performed in a hydrolyzate obtained from a pretreatment at 130 °C with NaOH solution (1...
June 19, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28627452/engineering-of-unconventional-yeast-yarrowia-lipolytica-for-efficient-succinic-acid-production-from-glycerol-at-low-ph
#14
Zhiyong Cui, Cuijuan Gao, Jiaojiao Li, Jin Hou, Carol Sze Ki Lin, Qingsheng Qi
Yarrowia lipolytica is considered as a potential candidate for succinic acid production because of its innate ability to accumulate citric acid cycle intermediates and its tolerance to acidic pH. Previously, a succinate-production strain was obtained through the deletion of succinate dehydrogenase subunit encoding gene Ylsdh5. However, the accumulation of by-product acetate limited further improvement of succinate production. Meanwhile, additional pH adjustment procedure increased the downstream cost in industrial application...
June 13, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28625678/rapid-protein-production-from-stable-cho-cell-pools-using-plasmid-vector-and-the-cumate-gene-switch
#15
Adeline Poulain, Sylvie Perret, Félix Malenfant, Alaka Mullick, Bernard Massie, Yves Durocher
To rapidly produce large amounts of recombinant proteins, the generation of stable Chinese Hamster Ovary (CHO) cell pools represents a useful alternative to large-scale transient gene expression (TGE). We have developed a cell line (CHO(BRI/rcTA)) allowing the inducible expression of recombinant proteins, based on the cumate gene switch. After the identification of optimal plasmid DNA topology (supercoiled vs linearized plasmid) for PEIpro™ mediated transfection and of optimal conditions for methionine sulfoximine (MSX) selection, we were able to generate CHO(BRI/rcTA) pools producing high levels of recombinant proteins...
June 15, 2017: Journal of Biotechnology
https://www.readbyqxmd.com/read/28624728/nitrite-production-from-urine-for-sulfide-control-in-sewers
#16
Min Zheng, Zhiqiang Zuo, Yizhen Zhang, Yujia Cui, Qian Dong, Yanchen Liu, Xia Huang, Zhiguo Yuan
Most commonly used methods for sewer sulfide control involves dosing chemical agents to wastewater, which incurs high operational costs. Here, we propose and demonstrate a cost-effective and environmentally attractive approach to sewer sulfide control through urine separation and its subsequent conversion to nitrite prior to intermittent dosage to sewers. Urine collected from a male toilet urinal was fed to laboratory-scale sequencing batch reactors. The reactors stably converted roughly 50% of the nitrogen in urine to nitrite, with high abundance (at 17...
May 23, 2017: Water Research
https://www.readbyqxmd.com/read/28623019/exogenous-addition-of-h2-for-an-in-situ-biogas-upgrading-through-biological-reduction-of-carbon-dioxide-into-methane
#17
Daniel Girma Mulat, Freya Mosbæk, Alastair James Ward, Daniela Polag, Markus Greule, Frank Keppler, Jeppe Lund Nielsen, Anders Feilberg
Biological reduction of CO2 into CH4 by exogenous addition of H2 is a promising technology for upgrading biogas into higher CH4 content. The aim of this work was to study the feasibility of exogenous H2 addition for an in situ biogas upgrading through biological conversion of the biogas CO2 into CH4. Moreover, this study employed systematic study with isotope analysis for providing comprehensive evidence on the underlying pathways of CH4 production and upstream processes. Batch reactors were inoculated with digestate originating from a full-scale biogas plant and fed once with maize leaf substrate...
June 13, 2017: Waste Management
https://www.readbyqxmd.com/read/28622792/a-cross-sectional-field-study-on-potential-associations-between-feed-quality-measures-and-usage-of-antimicrobials-in-commercial-mink-neovison-vison
#18
V F Jensen, H M Sommer, T Struve, J Clausen, M Chriél
Feed quality is generally assumed to affect health status in animal production. In previous studies, the feed producer has been found to affect the occurrence of gastrointestinal disease and antimicrobial use in Mink (Neovison vison). Mink are fed with moist, freshly produced feed, based on perishable ingredients. The objective of this study was to investigate the potential effect of specific feed parameters on antimicrobial use on herd level. The study was cross-sectional, including 1472 mink herds, responsible for 97% of oral antimicrobials prescribed for Danish mink during the study period, 2012-2014...
August 1, 2017: Preventive Veterinary Medicine
https://www.readbyqxmd.com/read/28619018/efficient-soluble-expression-of-disulfide-bonded-proteins-in-the-cytoplasm-of-escherichia-coli-in-fed-batch-fermentations-on-chemically-defined-minimal-media
#19
Anna Gąciarz, Narendar Kumar Khatri, M Lourdes Velez-Suberbie, Mirva J Saaranen, Yuko Uchida, Eli Keshavarz-Moore, Lloyd W Ruddock
BACKGROUND: The production of recombinant proteins containing disulfide bonds in Escherichia coli is challenging. In most cases the protein of interest needs to be either targeted to the oxidizing periplasm or expressed in the cytoplasm in the form of inclusion bodies, then solubilized and re-folded in vitro. Both of these approaches have limitations. Previously we showed that soluble expression of disulfide bonded proteins in the cytoplasm of E. coli is possible at shake flask scale with a system, known as CyDisCo, which is based on co-expression of a protein of interest along with a sulfhydryl oxidase and a disulfide bond isomerase...
June 15, 2017: Microbial Cell Factories
https://www.readbyqxmd.com/read/28617288/fate-of-selected-pharmaceutically-active-compounds-in-the-integrated-fixed-film-activated-sludge-process
#20
K J Murray, W J Parker, L M Bragg, M R Servos
The potential for integrated fixed film activated sludge (IFAS) processes to achieve enhanced transformation of pharmaceuticals relative to conventional activated sludge (CAS) processes was assessed. Previous studies have focused on direct comparisons of parallel reactors with and without fixed film carriers and little information is available on the impacts of how varying operating parameters impact the differences in observed pharmaceutical compound (PC) transformation capabilities between CAS reactors and those equipped with both an activated sludge (AS) and fixed film carriers...
June 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
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