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Low ph tolerance

Fahime Mohammadi, Morteza Eshaghi, Shabnam Razavi, Davood Darban Sarokhalil, Malihe Talebi, Mohammad Reza Pourshafie
The purpose of the present study was to isolate Lactobacillus bacteria from mother's milk and to assess their probiotic potential. Sixty breast milk samples were collected from the volunteered mothers aged from 19-35 and from rural areas of Lorestan and Markazi Provinces, Iran. At first, 970 bacill-shaped bacterial colonies were isolated from these samples and stored in proper condition. Two hundred isolates were randomly selected and investigated for their ability to tolerate acidic condition and to tolerate bile salt as well...
March 15, 2018: Microbial Pathogenesis
Chunyan Chen, Ni Sun, Dongsheng Li, Sihua Long, Xiaoyu Tang, Guoqing Xiao, Linyuan Wang
Kitchen waste oil (KWO) from catering industries or households was used as a low-cost carbon source for producing biosurfactants by self-isolated Pseudomonas aeruginosa. Fermentation performance with KWO was superior to those with four other carbon sources, with higher optical density (OD600 ) of 2.33 and lower interfacial tension of 0.57 mN/m. Culture conditions for biosurfactant production were optimized, with optimal pH of 8.0 and nitrogen source concentration of 2.0 g/L, respectively. The results of infrared spectroscopy and liquid chromatography-mass spectrometry (LC-MS) showed that the biosurfactant was a mixture of six rhamnolipid congeners, among which Rha-Rha-C10 -C10 and Rha-C10 -C10 were the main components, with mass fraction of approximately 34...
March 16, 2018: Environmental Science and Pollution Research International
Jiao Jiang, Krista M Sumby, Joanna F Sundstrom, Paul R Grbin, Vladimir Jiranek
High concentrations of ethanol, low pH, the presence of sulfur dioxide and some polyphenols have been reported to inhibit Oenococcus oeni growth, thereby negatively affecting malolactic fermentation (MLF) of wine. In order to generate superior O. oeni strains that can conduct more efficient MLF, despite these multiple stressors, a continuous culture approach was designed to directly evolve an existing ethanol tolerant O. oeni strain, A90. The strain was grown for ∼350 generations in a red wine-like environment with increasing levels of stressors...
August 2018: Food Microbiology
Yuqin Shi, Jun Liu, Qiaojuan Yan, Xin You, Shaoqing Yang, Zhengqiang Jiang
Prebiotic effects of curdlan (1 → 3)-β-d-glucan oligosaccharides (GOS) were examined. GOS was tolerant against simulated gastrointestinal digestion, as well as low pH, thermal, and Maillard reaction conditions likely occurred during food processing. Growth of tested Lactobacillus (L.) strains was improved by GOS except L. brevis NRRL B-4527. E. coli did not grow on GOS as the only carbon source. In vitro batch fermentation using human faecal microbiota showed that GOS significantly increased the population of Lactobacillus sp...
May 15, 2018: Carbohydrate Polymers
Sabina Rossini Oliva, M Dolores Mingorance, Dayan Sanhueza, Stephen C Fry, Eduardo O Leidi
BACKGROUND AND AIMS: Tolerance to soil acidity was studied in two species of Ericaceae that grow in mine-contaminated soils (S Portugal, SW Spain) to find out if there are interspecific variations in H+ tolerance which might be related to their particular location. METHODS: Tolerance to H+ toxicity was tested in nutrient solutions using seeds collected in SW Spain. Plant growth and nutrient contents in leaves, stems and roots were determined. Viability tests and proton exchange were studied in roots exposed, short-term, to acidic conditions...
March 2, 2018: Plant Physiology and Biochemistry: PPB
De-Mei Meng, Yu-Jie Lv, Jing-Fang Zhao, Qing-Yan Liu, Lin-Yue Shi, Jun-Ping Wang, Yong-Hai Yang, Zhen-Chuan Fan
VpDef is a novel defensin isolated from the clam Venerupis philippinarum. Previously it was expressed in Escherichia coli; however, the E. coli-derived recombinant VpDef did not show effective antimicrobial activity against Staphyloccocus aureus or the Gram-negative bacteria tested. As such, the goal of this study was to design, express, and purify a recombinant VpDef (rVpDef) in Pichia pastoris and to determine its antibacterial potency and stability. A 6.9 KDa rVpDef was successfully expressed as a secreted peptide in P...
March 6, 2018: Protein Expression and Purification
Jaroslav Vrba, Markéta Macholdová, Linda Nedbalová, Jiří Nedoma, Michal Šorf
Extracellular phosphatase activity (PA) has been used as an overall indicator of P depletion in lake phytoplankton. However, detailed insights into the mechanisms of PA regulation are still limited, especially in the case of acid phosphatases. The novel substrate ELF97 phosphate allows for tagging PA on single cells in an epifluorescence microscope. This fluorescence-labeled enzyme activity (FLEA) assay enables for autecological studies in natural phytoplankton and algal cultures. We combined the FLEA assay with image analysis to measure cell-specific acid PA in two closely related species of the genus Coccomyxa (Trebouxiophyceae, Chlorophyta) isolated from two acidic lakes with distinct P availability...
2018: Frontiers in Microbiology
Hui Fang, Xiao-Yu Qin, Kai-Duan Zhang, Yong Nie, Xiao-Lei Wu
The six- and seven-subunit Na+ /H+ antiporters (Mrp) are widely distributed in bacteria. They are reported to be integral for pH homeostasis in alkaliphilic bacteria when adapting to high pH environments. In this study, operons encoding for the six-subunit Na+ /H+ antiporters were found in the genomes of all studied Dietzia strains, which have different alkaline-resistant abilities. Disruption of the operon in the strain Dietzia sp. DQ12-45-1b which leads to declined growth in presence of hypersaline and alkaline conditions suggested that the six-subunit Na+ /H+ antiporter played an important role in hypersaline and alkaline resistance...
March 3, 2018: Applied Microbiology and Biotechnology
Xin-Yu Han, Huang Yang, Shi-Tao Rao, Guang-Yu Liu, Meng-Jun Hu, Bing-Chang Zeng, Min-Jie Cao, Guang-Ming Liu
The Maillard reaction was established to reduce the sensitization of tropomyosin (TM) and arginine kinase (AK) from Scylla paramamosain, and the mechanism of the attenuated sensitization was investigated. In the present study, the Maillard reaction conditions were optimized for heating at 100 °C for 60 min (pH 8.5) with arabinose. A low level of allergenicity in mice was shown by the levels of allergen-specific antibodies, and more Th1 and less Th2 cells cytokines produced and associated transcription factors with the Maillard reacted allergen (mAllergen)...
March 2, 2018: Journal of Agricultural and Food Chemistry
D F Campos, A L Val, V M F Almeida-Val
The metabolism of fishes is profoundly affected by environmental factors such as temperature, oxygen concentration, and pH levels. Also, biotic elements, for instance, activity levels of species, have been suggested to affect the energy demand, driving their capacity to support environmental challenges. The present work aims to investigate the effects of the lifestyle and swimming activities levels of fishes living in Amazon forest stream on the aerobic metabolism and thermal tolerance. Intermittent flow respirometry was used to measure routine metabolic rate and thermal maximum metabolic rate with a thermal ramp methodology...
February 2018: Journal of Thermal Biology
Chunyu Zhang, Xiaoyan Dong, Zheng Guo, Yan Sun
Enzymes are promising biocatalysts for the production or degradation of chemical compounds, but low stabilities of free enzymes restrict their industrial applications. Therefore, development of effective immobilization methods to maintain or increase enzyme activity and stability remains a challenge. In this work, a novel support made of zwitterionic polymer-grafted silica nanoparticles (p-SNPs) was fabricated and Candida rugosa lipase (CRL) was covalently attached onto the p-SNPs. The zwitterionic polymer was a product of the reaction between poly(maleic anhydride-alt-1-octadecene) and N,N-dimethylenediamine and contained a cetane side chain...
February 14, 2018: Journal of Colloid and Interface Science
Jaime Romero, Carolina Ilabaca, Mauricio Ruiz, Carla Jara
The presence and load of species of LAB at the end of the malolactic fermentation (MLF) were investigated in 16 wineries from the different Chilean valleys (Limarí, Casablanca, Maipo, Rapel, and Maule Valleys) during 2012 and 2013, using PCR-RFLP and qPCR. Oenococcus oeni was observed in 80% of the samples collected. Dominance of O. oeni was reflected in the bacterial load ( O. oeni /total bacteria) measured by qPCR, corresponding to >85% in most of the samples. A total of 178 LAB isolates were identified after sequencing molecular markers, 95 of them corresponded to O...
2018: Frontiers in Microbiology
Sabarathinam Shanmugam, Chongran Sun, Xiaoming Zeng, Yi-Rui Wu
A novel Clostridium sp. strain WST isolated from mangrove sediments demonstrated its unique characteristics of producing high titer of biobutanol from low concentration of substrates via anaerobic fermentation. The strain is able to convert glucose and galactose to high amount of biobutanol up to 16.62 and 12.11 g/L, respectively, and the yields of 0.54 and 0.55 g/g were determined to be much higher than those from the previous reports on Clostridial batch fermentation. Moreover, the inherent strong regulatory system of strain WST also prompts itself to perform the fermentation process without any requirement of pH control...
February 20, 2018: Bioresource Technology
Wen Du, Chunlong Sun, Jun Wang, Baoqin Wang, Zhigang Yao, Fanzhu Qu, Jiangbao Xia, Wenjun Xie, Jingkuan Sun, Daixiang Duan
A new type of thermostable laccase was isolated from Paraphoma sp. GZS18, and its partial enzymatic properties were determined. A strain GZS18 of laccase with high yield was screened from forest soil and identified as Paraphoma sp. GZS18 through morphological characteristics and ITS sequence analysis. The laccase of Paraphoma sp. GZS18 (Lac-P) was obtained through cation-anion exchange chromatography, gel filtration chromatography, and other purification processes. The testing result shows that Lac-P is a single protein of 75 kDa, and the 11 amino acid sequences in the N-terminal are AXa VSVASREMT (Xa was the non-standard protein)...
March 2018: 3 Biotech
M Guiral, C Neitzel, M Salvador Castell, N Martinez, M T Giudici-Orticoni, J Peters
Pure phospholipids and membrane fragments from bacterial cells living under various conditions were studied against the influence of the surrounding acidity on the internal dynamics. For that we compared mean square displacements extracted from elastic incoherent neutron scattering data, measured both at low and at neutral pH, of the phospholipids 1,2-dimyristoyl-sn-glycero-3-phosphocholine and of samples from neutralophilic and acidophilic micro-organisms (some being hyperthermophilic and others mesophilic)...
February 16, 2018: European Physical Journal. E, Soft Matter
Fatih Cakar, Franz G Zingl, Manuel Moisi, Joachim Reidl, Stefan Schild
The facultative human pathogen Vibrio cholerae changes its transcriptional profile upon oral ingestion by the host to facilitate survival and colonization fitness. Here, we used a modified version of recombination-based in vivo expression technology to investigate gene silencing during the in vivo passage, which has been understudied. Using a murine model of cholera, we screened a V. cholerae transposon library composed of 10,000 randomly generated reporter fusions and identified 101 in vivo repressed ( ivr ) genes...
February 20, 2018: Proceedings of the National Academy of Sciences of the United States of America
Mi Feng, Hua Yin, Yajuan Cao, Hui Peng, Guining Lu, Zehua Liu, Zhi Dang
Cd-induced stress response of Phanerochaete chrysosporium during the biodegradation of BDE-47 was investigated in this study, with the goal of elucidating the tolerance behavior and the detoxification mechanisms of P. chrysosporium to resist the Cd stress in the course of BDE-47 biodegradation, which has implications for expanding the application of P. chrysosporium in the bioremediation of Cd and BDE-47 combined pollution. The results suggested that single BDE-47 exposure did not induce obvious oxidative stress in P...
February 14, 2018: Ecotoxicology and Environmental Safety
Ifeoluwa Adekoya, Adewale Obadina, Cynthia Chilaka Adaku, Marthe De Boevre, Sheila Okoth, Sarah De Saeger, Patrick Njobeh
Beer, a beverage consumed throughout the world, is mainly derived from cereals. In this study, fungal and mycotoxin contamination, as well as the physicochemical properties of maize-based opaque beer (umqombothi) obtained from the Gauteng province of South Africa, was investigated. The mean water activity, pH and total titratable acidity of the analysed beer samples were 0.91, 3.76 and 1.20% lactic acid, respectively. The investigation revealed Aspergillus, Penicillium, Phoma and Saccharomyces as the predominant fungal genera with a mean fungal load of 3...
February 9, 2018: International Journal of Food Microbiology
Fujin Ai, Na Wang, Xiaoman Zhang, Tianying Sun, Qi Zhu, Wei Kong, Feng Wang, Guangyu Zhu
Upconversion nanoparticles (UCNPs) are widely utilized for photodynamic therapy (PDT) due to their specific upconverting luminescence that utilizes near infrared (NIR) light to excite photosensitizers (PSs) for PDT. The efficiency of UCNP-based PDT will be improved if the cancer-targeting property of nanomedicine is enhanced. Herein, we employed the pH low insertion peptide (pHLIP), a cancer-targeting moiety, to functionalize an 808 nm excited UCNP-based nanoplatform that has a minimized over-heating effect to perform PDT...
February 16, 2018: Nanoscale
Emmanuel S Burgos, Ryan O Walters, Derek M Huffman, David Shechter
Methyltransferases use S -adenosyl-l-methionine (SAM) to deposit methyl marks. Many of these epigenetic 'writers' are associated with gene regulation. As cancer etiology is highly correlated with misregulated methylation patterns, methyltransferases are emerging therapeutic targets. Successful assignment of methyltransferases' roles within intricate biological networks relies on (1) the access to enzyme mechanistic insights and (2) the efficient screening of chemical probes against these targets. To characterize methyltransferases in vitro and in vivo , we report a highly-sensitive one-step deaminase-linked continuous assay where the S -adenosyl-l-homocysteine (SAH) enzyme-product is rapidly and quantitatively catabolized to S -inosyl-l-homocysteine (SIH)...
September 1, 2017: Chemical Science
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