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Lactic acid stress yeast

Limin Kung, Megan L Smith, Erica Benjamim da Silva, Michelle C Windle, Thiago C da Silva, Stephanie A Polukis
We evaluated the effectiveness of an additive comprising sodium benzoate, potassium sorbate, and sodium nitrite (SSL) as active ingredients for its ability to improve the aerobic stability of corn silages made in North America. In experiment 1, treatment with SSL (1.5 and 2.0 L/t) on whole-plant corn (WPC) was compared with treatment with an additive containing buffered propionic acid and citric acid (BPA; 2 L/t) on corn harvested at 32 and 38% DM and ensiled for 120 d. Silage treated with BPA was higher in ammonia-N and propionic acid relative to other treatments...
April 11, 2018: Journal of Dairy Science
Lacey Lemonakis, KaWang Li, Jeremy M Adler, Cangliang Shen
This study aims to evaluate the microbiological quality and efficacy of antimicrobials to inactivate unstressed or cold-stress adapted Salmonella and Enterococcus on broiler carcasses and wings processed at a small USDA-inspected slaughter facility in West Virginia. The first part of the study included 42 carcasses that were pre- and secondarily-enriched in bacterial media followed by streak-plating onto XLT-4 and HardyCHROM™-agar Salmonella and confirmation using an API20E-kit. The aerobic plate counts (APC), Escherichia coli (ECC), total coliforms (TCC), and yeast/molds were analyzed on petri-films...
September 1, 2017: Poultry Science
Y-M Bae, J-H Yoon, J-Y Kim, S-Y Lee
AIM: In this study, the effects of the addition of salt to treatment with acids (one of several organic acids and salt in various solutions including rich or minimal broth, buffer, or distilled water) on the reduction of Escherichia coli O157:H7 were investigated. The protein expression profiles corresponding to acid stress (acetic acid) with or without salt addition were studied using a comparative proteomic analysis of E. coli O157:H7. METHODS AND RESULTS: When acetic, lactic, or propionic acid was combined with 3% NaCl, mutually antagonistic effects of acid and salt on viability of E...
January 2018: Journal of Applied Microbiology
Mingzhan Toh, Shao Quan Liu
This study evaluated the influence of three inactivated yeast derivatives (IYDs) used in wine production, namely OptiRed(®), OptiWhite(®) and Noblesse(®), on the viability of the probiotic strain Lactobacillus rhamnosus HN001 in an acidic environment. Addition of the IYDs at 3 g/L significantly enhanced the survival of the probiotic bacteria by 2.75-4.05 log cycles after 10-h exposure in a pH 3.0 buffer. Acid stress assay with IYD components obtained after centrifugation and filtration revealed that water-soluble compounds were responsible for improving the acid tolerance of L...
December 2017: AMB Express
Luc De Vuyst, Simon Van Kerrebroeck, Frédéric Leroy
From a microbiological perspective, sourdough is to be considered as a specific and stressful ecosystem, harboring yeasts and lactic acid bacteria (LAB), that is used for the production of baked goods. With respect to the metabolic impact of the sourdough microbiota, acidification (LAB), flavor formation (LAB and yeasts), and leavening (yeasts and heterofermentative LAB species) are most noticeable. Three distinct types of sourdough fermentation processes can be discerned based on the inocula applied, namely backslopped ones (type 1), those initiated with starter cultures (type 2), and those initiated with a starter culture followed by backslopping (type 3)...
2017: Advances in Applied Microbiology
Nozomi Kawazoe, Yukio Kimata, Shingo Izawa
Since acetic acid inhibits the growth and fermentation ability of Saccharomyces cerevisiae, it is one of the practical hindrances to the efficient production of bioethanol from a lignocellulosic biomass. Although extensive information is available on yeast response to acetic acid stress, the involvement of endoplasmic reticulum (ER) and unfolded protein response (UPR) has not been addressed. We herein demonstrated that acetic acid causes ER stress and induces the UPR. The accumulation of misfolded proteins in the ER and activation of Ire1p and Hac1p, an ER-stress sensor and ER stress-responsive transcription factor, respectively, were induced by a treatment with acetic acid stress (>0...
2017: Frontiers in Microbiology
R Doug Wagner, Shemedia J Johnson, Zhixia Yan Danielsen, Jin-Hee Lim, Thilak Mudalige, Sean Linder
Mucous-penetrating nanoparticles consisting of poly lactic acid-co-glycolic acid (PLGA)-polyethylene glycol (PEG) could improve targeting of microbicidal drugs for sexually transmitted diseases by intravaginal inoculation. Nanoparticles can induce inflammatory responses, which may exacerbate the inflammation that occurs in the vaginal tracts of women with yeast infections. This study evaluated the effects of these drug-delivery nanoparticles on VK2(E6/E7) vaginal epithelial cell proinflammatory responses to Candida albicans yeast infections...
2017: PloS One
David Laureys, Amandine Van Jean, Jean Dumont, Luc De Vuyst
A poorly performing industrial water kefir production process consisting of a first fermentation process, a rest period at low temperature, and a second fermentation process was characterized to elucidate the causes of its low water kefir grain growth and instability. The frozen-stored water kefir grain inoculum was thawed and reactivated during three consecutive prefermentations before the water kefir production process was started. Freezing and thawing damaged the water kefir grains irreversibly, as their structure did not restore during the prefermentations nor the production process...
April 2017: Applied Microbiology and Biotechnology
Eugene Fletcher, Amir Feizi, Markus M M Bisschops, Björn M Hallström, Sakda Khoomrung, Verena Siewers, Jens Nielsen
Tolerance of yeast to acid stress is important for many industrial processes including organic acid production. Therefore, elucidating the molecular basis of long term adaptation to acidic environments will be beneficial for engineering production strains to thrive under such harsh conditions. Previous studies using gene expression analysis have suggested that both organic and inorganic acids display similar responses during short term exposure to acidic conditions. However, biological mechanisms that will lead to long term adaptation of yeast to acidic conditions remains unknown and whether these mechanisms will be similar for tolerance to both organic and inorganic acids is yet to be explored...
January 2017: Metabolic Engineering
Sofia V Poimenidou, Danai-Natalia Chatzithoma, George-John Nychas, Panagiotis N Skandamis
Pathogens found on fresh produce may encounter low temperatures, high acidity and limited nutrient availability. The aim of this study was to evaluate the effect of habituation of Listeria monocytogenes on cherry tomatoes or lettuce leaves on its subsequent response to inhibitory levels of acid, osmotic and heat stress. Habituation was performed by inoculating lettuce coupons, whole cherry tomatoes or tryptic soy broth (TSB) with a three-strains composite of L. monocytogenes, which were further incubated at 5°C for 24 hours or 5 days...
2016: PloS One
Masaharu Tsuji
Microbes growing at subzero temperatures encounter numerous growth constraints. However, fungi that inhabit cold environments can grow and decompose organic compounds under subzero temperatures. Thus, understanding the cold-adaptation strategies of fungi under extreme environments is critical for elucidating polar-region ecosystems. Here, I report that two strains of the Antarctic basidiomycetous yeast Mrakia blollopis exhibited distinct growth characteristics under subzero conditions: SK-4 grew efficiently, whereas TKG1-2 did not...
July 2016: Royal Society Open Science
Luc De Vuyst, Henning Harth, Simon Van Kerrebroeck, Frédéric Leroy
Together with acidifying lactic acid bacteria, yeasts play a key role in the production process of sourdough, where they are either naturally present or added as a starter culture. Worldwide, a diversity of yeast species is encountered, with Saccharomyces cerevisiae, Candida humilis, Kazachstania exigua, Pichia kudriavzevii, Wickerhamomyces anomalus, and Torulaspora delbrueckii among the most common ones. Sourdough-adapted yeasts are able to withstand the stress conditions encountered during their growth, including nutrient starvation as well as the effects of acidic, oxidative, thermal, and osmotic stresses...
December 19, 2016: International Journal of Food Microbiology
Simon Van Kerrebroeck, Francisca Casanova C Bastos, Henning Harth, Luc De Vuyst
This study dealt with the influence of a crucial pH value of 4.0 on the microbiota of spontaneously fermented backslopped liquid wheat sourdoughs. Two spontaneously fermented wheat sourdough fermentation experiments were carried out, one without control of the pH and one with the pH kept constant at pH4.0, both during nine backslopping steps. In each case, two additional backslopping steps were carried out, with the pH kept constant at 4.0 and with free pH, respectively. Keeping the pH constant at 4.0 changed the microbial community dynamics and metabolite kinetics of the sourdough fermentations...
December 19, 2016: International Journal of Food Microbiology
Joao A Paulo, Jeremy D O'Connell, Robert A Everley, Jonathon O'Brien, Micah A Gygi, Steven P Gygi
UNLABELLED: The budding yeast Saccharomyces cerevisiae is a model system for investigating biological processes. Cellular events are known to be dysregulated due to shifts in carbon sources. However, the comprehensive proteomic alterations thereof have not been fully investigated. Here we examined proteomic alterations in S. cerevisiae due to the adaptation of yeast from glucose to nine different carbon sources - maltose, trehalose, fructose, sucrose, glycerol, acetate, pyruvate, lactic acid, and oleate...
October 4, 2016: Journal of Proteomics
Riyanto Heru Nugroho, Katsunori Yoshikawa, Fumio Matsuda, Hiroshi Shimizu
In Saccharomyces cerevisiae, proline is a stress protectant interacting with other substrate uptake systems against oxidative stress under low pH conditions. In this study, we performed metabolomics analysis to investigate the response associated with an increase in cell growth rates and maximum densities when cells were treated with proline under normal and acid stress conditions. Metabolome data show that concentrations of components of central metabolism are increased in proline-treated S. cerevisiae. No consumption of proline was observed, suggesting that proline does not act as a nutrient but regulates metabolic state and growth of cells...
November 2016: Bioprocess and Biosystems Engineering
Arun S Rajkumar, Guodong Liu, David Bergenholm, Dushica Arsovska, Mette Kristensen, Jens Nielsen, Michael K Jensen, Jay D Keasling
Advances in synthetic biology and our understanding of the rules of promoter architecture have led to the development of diverse synthetic constitutive and inducible promoters in eukaryotes and prokaryotes. However, the design of promoters inducible by specific endogenous or environmental conditions is still rarely undertaken. In this study, we engineered and characterized a set of strong, synthetic promoters for budding yeast Saccharomyces cerevisiae that are inducible under acidic conditions (pH ≤ 3). Using available expression and transcription factor binding data, literature on transcriptional regulation, and known rules of promoter architecture we improved the low-pH performance of the YGP1 promoter by modifying transcription factor binding sites in its upstream activation sequence...
September 30, 2016: Nucleic Acids Research
Mostafa Gouda, Amr Moustafa, Laila Hussein, Mohamed Hamza
BACKGROUND: The beneficial effects of the polyphenol (PP) rich fruits and Lactic acid bacteria fermented foods had been reported as cost-effective strategies for health promotion. Randomized controlled trial was designed to test the hypothesis that daily intake of polyphenol rich pomegranate juice (PGJ) or/ and lactic acid bacteria fermented sobya (FS) improved selected biomarkers of relevance to heath status. METHODS: The design of the human trial consisted of 35 healthy adults, who were distributed to 5 equal groups; The first group served as control and received no supplements; the second group received fresh apricot fruits (200 g); the third (PGJ) (250 g), the fourth a mixture of PGJ (150 g) and FS (140 g) and the fifth group received (FS) (170 g)...
May 12, 2016: Nutrition Journal
Minetaka Sugiyama, Shin-Pei Akase, Ryota Nakanishi, Yoshinobu Kaneko, Satoshi Harashima
Polylactic acid plastics are receiving increasing attention for the control of atmospheric CO2 emissions. Lactic acid, the building block for polylactic acid, is produced by fermentation technology from renewable carbon sources. The yeast Saccharomyces cerevisiae, harboring the lactate dehydrogenases gene (LDH), produces lactic acid at a large scale due to its strong acid resistance, to its simple nutritional requirements and to its ease of genetic engineering. Since improvement of lactic acid resistance is correlated with an increase of lactic acid production under non-neutralizing condition, we isolated a novel gene that enhances lactic acid resistance using a multi-copy yeast genomic DNA library...
October 2016: Journal of Bioscience and Bioengineering
Nadia Maria Berterame, Danilo Porro, Diletta Ami, Paola Branduardi
BACKGROUND: Lactic acid is a versatile chemical platform with many different industrial applications. Yeasts have been demonstrated as attractive alternative to natural lactic acid producers since they can grow at low pH, allowing the direct purification of the product in the desired acidic form. However, when very high concentrations of organic acids are reached, the major limitation for a viable production is the toxic effect of the product. The accumulation in the cytosol of H(+) and of the weak organic counter-anions triggers a cellular reprogramming...
2016: Microbial Cell Factories
Saeed Kaboli, Tetsuya Miyamoto, Keisuke Sunada, Yu Sasano, Minetaka Sugiyama, Satoshi Harashima
Saccharomyces cerevisiae strains from industrial and natural geographical environments are reported to show great variation in copy number of chromosomal regions. Such variation contributes to the mechanisms underlying adaptation to different environments. Here, we created and phenotypically analyzed segmentally haploidized strains, each harboring a deletion of one copy of approximately 100-300 kb of the left or right terminal region of 16 chromosomes in a diploid strain by using a PCR-mediated chromosomal deletion method...
June 2016: Journal of Bioscience and Bioengineering
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