scholarly journals Transcriptomic Analysis of Pediococcus pentosaceus Reveals Carbohydrate Metabolic Dynamics Under Lactic Acid Stress

2021 ◽  
Vol 12 ◽  
Author(s):  
Dong Han ◽  
Qiaojuan Yan ◽  
Jun Liu ◽  
Zhengqiang Jiang ◽  
Shaoqing Yang
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Carbohydrate Metabolism ◽  
Stress Responses ◽  
Protective Efficacy ◽  
Acid Stress ◽  
Cell Factory ◽  
Transcriptional Responses ◽  
Pediococcus Pentosaceus ◽  
Ecological Fitness

Stress physiology of lactic acid bacteria (LAB) is crucial to their ecological fitness and applicational implications. As a self-imposed stress, lactic acid is the major final metabolic product of LAB and its accumulation can be detrimental to bacterial cells. However, the relationship between LAB carbohydrate metabolism, the primary energy supplying bioactivities, and lactic acid stress responses is not fully understood. Pediococcus pentosaceus has been recognized as an important cell factory and demonstrated probiotic activities. This study investigated behavior of P. pentosaceus under lactic and acetic acid stresses, particularly with supplementations of metabolizable carbohydrates. Lactic and acetic acid retain similar growth stagnation effect, and both resulted in cell death in P. pentosaceus. All metabolizable carbohydrates improved bacterial survival compared to lactic acid control, while xylooligosaccharides (XOS) exerted the highest viability protective efficacy, 0.82 log CFU/mL higher population survived than other carbohydrates after 30 h of incubation. RNA-seq pipeline showcased the intensive global transcriptional responses of P. pentosaceus to lactic acid, which caused significant regulations (more than 2 Log2 fold) of 16.5% of total mRNA coding genes. Glucose mainly led to gene suppressions (83 genes) while XOS led to gene up-regulations (19 genes) under lactic acid stress. RT-qPCR study found that RNA polymerase-centered transcriptional regulation is the primary regulatory approach in evaluated culture conditions. The synergy between lactic acid stress and carbohydrate metabolism should be attentively contemplated in future studies and applications.

Microarray-based transcriptome ofListeria monocytogenesadapted to sublethal concentrations of acetic acid, lactic acid, and hydrochloric acid

2012 ◽  
Vol 58 (9) ◽  
pp. 1112-1123 ◽  
Author(s):  
Girum Tadesse Tessema ◽  
Trond Møretrø ◽  
Lars Snipen ◽  
Even Heir ◽  
Askild Holck ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Hydrochloric Acid ◽  
Organic Acids ◽  
Compatible Solutes ◽  
Foodborne Pathogen ◽  
Acid Stress ◽  
Low Ph ◽  
Transcriptional Responses ◽  
Ph Stress

Listeria monocytogenes , an important foodborne pathogen, commonly encounters organic acids in food-related environments. The transcriptome of L. monocytogenes L502 was analyzed after adaptation to pH 5 in the presence of acetic acid, lactic acid, or hydrochloric acid (HCl) at 25 °C, representing a condition encountered in mildly acidic ready-to-eat food kept at room temperature. The acid-treated cells were compared with a reference culture with a pH of 6.7 at the time of RNA harvesting. The number of genes and magnitude of transcriptional responses were higher for the organic acids than for HCl. Protein coding genes described for low pH stress, energy transport and metabolism, virulence determinates, and acid tolerance response were commonly regulated in the 3 acid-stressed cultures. Interestingly, the transcriptional levels of histidine and cell wall biosynthetic operons were upregulated, indicating possible universal response against low pH stress in L. monocytogenes. The opuCABCD operon, coding proteins for compatible solutes transport, and the transcriptional regulator sigL were significantly induced in the organic acids, strongly suggesting key roles during organic acid stress. The present study revealed the complex transcriptional responses of L. monocytogenes towards food-related acidulants and opens the roadmap for more specific and in-depth future studies.

Characterization of Low Salinity Stress in Vibrio parahaemolyticus

2012 ◽  
Vol 75 (2) ◽  
pp. 231-237 ◽  
Author(s):  
WEI SHEN HUANG ◽  
HIN-CHUNG WONG
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Stationary Phase ◽  
Salinity Stress ◽  
Vibrio Parahaemolyticus ◽  
Acid Stress ◽  
Low Ph ◽  
Exponential Phase ◽  
Low Salinity ◽  
Acetic Acid Treatment

Vibrio parahaemolyticus is a marine foodborne pathogenic bacterium commonly found in seawater or seafood. This bacterium often encounters low salinity stress when the contaminated seafood is washed with fresh water during food processing. This study was conducted to investigate the response of exponential- and stationary-phase cells of V. parahaemolyticus ST550 to lethal or sublethal low salinity. Tolerance to lethal low salinity (0.25% NaCl) was enhanced in V. parahaemolyticus cells in the exponential phase by previous adaptation in sublethal low salinity (0.6% NaCl). Low salinity–adapted cells in the exponential phase were also cross-protected against the challenge of lethal low pH, indifferent to heat, and sensitized to bile, acetic acid, and lactic acid stress. The adapted cells in the stationary phase were significantly protected against heat treatment at 44°C for 10 and 15 min, sensitized to bile and acetic acid treatment, and indifferent to low pH and lactic acid.

scholarly journals Survival or Growth of Escherichia coli O157:H7 in a Model System of Fresh Meat Decontamination Runoff Waste Fluids and Its Resistance to Subsequent Lactic Acid Stress

2005 ◽  
Vol 71 (10) ◽  
pp. 6228-6234 ◽  
Author(s):  
John Samelis ◽  
John N. Sofos ◽  
Patricia A. Kendall ◽  
Gary C. Smith
Keyword(s):  
Escherichia Coli ◽  
Acetic Acid ◽  
Lactic Acid ◽  
Acid Stress ◽  
Acid Resistance ◽  
Fresh Meat ◽  
Sterile Saline ◽  
E Coli ◽  
Acid Ph ◽  
Natural Flora

ABSTRACT A potential may exist for survival of and resistance development by Escherichia coli O157:H7 in environmental niches of meat plants applying carcass decontamination interventions. This study evaluated (i) survival or growth of acid-adapted and nonadapted E. coli O157:H7 strain ATCC 43895 in acetic acid (pH 3.6 ± 0.1) or in water (pH 7.2 ± 0.2) fresh beef decontamination runoff fluids (washings) stored at 4, 10, 15, or 25°C and (ii) resistance of cells recovered from the washings after 2 or 7 days of storage to a subsequent lactic acid (pH 3.5) stress. Corresponding cultures in sterile saline or in heat-sterilized water washings were used as controls. In acetic acid washings, acid-adapted cultures survived better than nonadapted cultures, with survival being greatest at 4°C and lowest at 25°C. The pathogen survived without growth in water washings at 4 and 10°C, while it grew by 0.8 to 2.7 log cycles at 15 and 25°C, and more in the absence of natural flora. E. coli O157:H7 cells habituated without growth in water washings at 4 or 10°C were the most sensitive to pH 3.5, while cells grown in water washings at 15 or 25°C were relatively the most resistant, irrespective of previous acid adaptation. Resistance to pH 3.5 of E. coli O157:H7 cells habituated in acetic acid washings for 7 days increased in the order 15°C > 10°C > 4°C, while at 25°C cells died off. These results indicate that growth inhibition by storage at low temperatures may be more important than competition by natural flora in inducing acid sensitization of E. coli O157:H7 in fresh meat environments. At ambient temperatures in meat plants, E. coli O157:H7 may grow to restore acid resistance, unless acid interventions are applied to inhibit growth and minimize survival of the pathogen. Acid-habituated E. coli O157:H7 at 10 to 15°C may maintain a higher acid resistance than when acid habituated at 4°C. These responses should be evaluated with fresh meat and may be useful for the optimization of decontamination programs and postdecontamination conditions of meat handling.

Responses of Staphylococcus aureus exposed to HCl and organic acid stress

2010 ◽  
Vol 56 (9) ◽  
pp. 777-792 ◽  
Author(s):  
Tone Mari Rode ◽  
Trond Møretrø ◽  
Solveig Langsrud ◽  
Øyvind Langsrud ◽  
Gjermund Vogt ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Acetic Acid ◽  
Lactic Acid ◽  
Organic Acid ◽  
Acid Stress ◽  
Food Poisoning ◽  
Transcriptional Response ◽  
Food Preservation ◽  
Growth Patterns ◽  
Aureus Strain

Staphylococcus aureus is an important food poisoning bacterium. In food preservation, acidification is a well-known method. Permeant weak organic acids, like lactic and acetic acids, are known to be more effective against bacteria than inorganic strong acids (e.g., HCl). Growth experiments and metabolic and transcriptional analyses were used to determine the responses of a food pathogenic S. aureus strain exposed to lactic acid, acetic acid, and HCl at pH 4.5. Lactic and acetic acid stress induced a slower transcriptional response and large variations in growth patterns compared with the responses induced by HCl. In cultures acidified with lactic acid, the pH of the medium gradually increased to 7.5 during growth, while no such increase was observed for bacteria exposed to acetic acid or HCl. Staphylococcus aureus increased the pH in the medium mainly through accumulation of ammonium and the removal of acid groups, resulting in increased production of diacetyl (2,3-butanedione) and pyrazines. The results showed flexible and versatile responses of S. aureus to different types of acid stress. As measured by growth inhibition, permeant organic acid stress introduced severe stress compared with the stress caused by HCl. Cells exposed to lactic acid showed specific mechanisms of action in addition to sharing many of the mechanisms induced by HCl stress.

scholarly journals DNA Macroarray Profiling of Lactococcus lactis subsp. lactis IL1403 Gene Expression during Environmental Stresses

2004 ◽  
Vol 70 (11) ◽  
pp. 6738-6747 ◽  
Author(s):  
Yi Xie ◽  
Lan-szu Chou ◽  
Adele Cutler ◽  
Bart Weimer
Keyword(s):  
Environmental Stress ◽  
Lactococcus Lactis ◽  
Internal Control ◽  
Stress Responses ◽  
Expression Patterns ◽  
Acid Stress ◽  
Acid Tolerance ◽  
Peptide Transport ◽  
Peptide Transporter ◽  
Transcriptional Responses

ABSTRACT This report describes the use of an oligonucleotide macroarray to profile the expression of 375 genes in Lactococcus lactis subsp. lactis IL1403 during heat, acid, and osmotic stress. A set of known stress-associated genes in IL1403 was used as the internal control on the array. Every stress response was accurately detected using the macroarray, compared to data from previous reports. As a group, the expression patterns of the investigated metabolic genes were significantly altered by heat, acid, and osmotic stresses. Specifically, 13 to 18% of the investigated genes were differentially expressed in each of the environmental stress treatments. Interestingly, the methionine biosynthesis pathway genes (metA-metB1 and metB2-cysK) were induced during heat shock, but methionine utilization genes, such as metK, were induced during acid stress. These data provide a possible explanation for the differences between acid tolerance mechanisms of L. lactis strains IL1403 and MG1363 reported previously. Several groups of transcriptional responses were common among the stress treatments, such as repression of peptide transporter genes, including the opt operon (also known as dpp) and dtpT. Reduction of peptide transport due to environmental stress will have important implications in the cheese ripening process. Although stress responses in lactococci were extensively studied during the last decade, additional information about this bacterium was gained from the use of this metabolic array.

scholarly journals Improvement of inhibitor tolerance in Saccharomyces cerevisiae by overexpression of the quinone oxidoreductase family gene YCR102C

2019 ◽  
Vol 19 (6) ◽  
Author(s):  
Hongqi Chen ◽  
Jie Li ◽  
Chun Wan ◽  
Qing Fang ◽  
Fengwu Bai ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Acetic Acid ◽  
Acid Stress ◽  
Acid Tolerance ◽  
Cell Factory ◽  
Quinone Oxidoreductase ◽  
Yeast Saccharomyces Cerevisiae ◽  
Inhibitor Tolerance ◽  
Family Gene ◽  
Novel Strategy

ABSTRACT Budding yeast Saccharomyces cerevisiae is widely used for lignocellulosic biorefinery. However, its fermentation efficiency is challenged by various inhibitors (e.g. weak acids, furfural) in the lignocellulosic hydrolysate, and acetic acid is commonly present as a major inhibitor. The effects of oxidoreductases on the inhibitor tolerance of S. cerevisiae have mainly focused on furfural and vanillin, whereas the influence of quinone oxidoreductase on acetic acid tolerance is still unknown. In this study, we show that overexpression of a quinone oxidoreductase-encoding gene, YCR102C, in S. cerevisiae, significantly enhanced ethanol production under acetic acid stress as well as in the inhibitor mixture, and also improved resistance to simultaneous stress of 40°C and 3.6 g/L acetic acid. Increased catalase activities, NADH/NAD+ ratio and contents of several metals, especially potassium, were observed by YCR102C overexpression under acetic acid stress. To our knowledge, this is the first report that the quinone oxidoreductase family protein is related to acid stress tolerance. Our study provides a novel strategy to increase lignocellulosic biorefinery efficiency using yeast cell factory.

scholarly journals Saccharomyces cerevisiae Fermentation of 28 Barley and 12 Oat Cultivars

Fermentation ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 59
Author(s):  
Timothy J. Tse ◽  
Daniel J. Wiens ◽  
Jianheng Shen ◽  
Aaron D. Beattie ◽  
Martin J. T. Reaney
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Acetic Acid ◽  
Lactic Acid ◽  
Succinic Acid ◽  
Alcoholic Fermentation ◽  
Ethanol Yield ◽  
Cereal Crops ◽  
Fermentation Products ◽  
Barley Cultivars ◽  
Oat Cultivars

As barley and oat production have recently increased in Canada, it has become prudent to investigate these cereal crops as potential feedstocks for alcoholic fermentation. Ethanol and other coproduct yields can vary substantially among fermented feedstocks, which currently consist primarily of wheat and corn. In this study, the liquified mash of milled grains from 28 barley (hulled and hull-less) and 12 oat cultivars were fermented with Saccharomyces cerevisiae to determine concentrations of fermentation products (ethanol, isopropanol, acetic acid, lactic acid, succinic acid, α-glycerylphosphorylcholine (α-GPC), and glycerol). On average, the fermentation of barley produced significantly higher amounts of ethanol, isopropanol, acetic acid, succinic acid, α-GPC, and glycerol than that of oats. The best performing barley cultivars were able to produce up to 78.48 g/L (CDC Clear) ethanol and 1.81 g/L α-GPC (CDC Cowboy). Furthermore, the presence of milled hulls did not impact ethanol yield amongst barley cultivars. Due to its superior ethanol yield compared to oats, barley is a suitable feedstock for ethanol production. In addition, the accumulation of α-GPC could add considerable value to the fermentation of these cereal crops.

scholarly journals Arginine Decarboxylase Is Essential for Pneumococcal Stress Responses

Pathogens ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 286
Author(s):  
Mary Frances Nakamya ◽  
Moses B. Ayoola ◽  
Leslie A. Shack ◽  
Mirghani Mohamed ◽  
Edwin Swiatlo ◽  
...  
Keyword(s):  
Stress Responses ◽  
Critical Role ◽  
Acid Stress ◽  
Arginine Decarboxylase ◽  
Arginine Deiminase ◽  
Dependent Manner ◽  
Cellular Processes ◽  
Opportunistic Human Pathogen ◽  
Thiol Peroxidase ◽  
The Impact

Polyamines such as putrescine, cadaverine, and spermidine are small cationic molecules that play significant roles in cellular processes, including bacterial stress responses and host–pathogen interactions. Streptococcus pneumoniae is an opportunistic human pathogen, which causes several diseases that account for significant morbidity and mortality worldwide. As it transits through different host niches, S. pneumoniae is exposed to and must adapt to different types of stress in the host microenvironment. We earlier reported that S. pneumoniae TIGR4, which harbors an isogenic deletion of an arginine decarboxylase (ΔspeA), an enzyme that catalyzes the synthesis of agmatine in the polyamine synthesis pathway, has a reduced capsule. Here, we report the impact of arginine decarboxylase deletion on pneumococcal stress responses. Our results show that ΔspeA is more susceptible to oxidative, nitrosative, and acid stress compared to the wild-type strain. Gene expression analysis by qRT-PCR indicates that thiol peroxidase, a scavenger of reactive oxygen species and aguA from the arginine deiminase system, could be important for peroxide stress responses in a polyamine-dependent manner. Our results also show that speA is essential for endogenous hydrogen peroxide and glutathione production in S. pneumoniae. Taken together, our findings demonstrate the critical role of arginine decarboxylase in pneumococcal stress responses that could impact adaptation and survival in the host.

scholarly journals Genome-scale target identification in Escherichia coli for high-titer production of free fatty acids

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Lixia Fang ◽  
Jie Fan ◽  
Shulei Luo ◽  
Yaru Chen ◽  
Congya Wang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Fatty Acids ◽  
Free Fatty Acids ◽  
Stress Responses ◽  
Metabolic Networks ◽  
Target Identification ◽  
High Titer ◽  
Cell Factory ◽  
Microbial Cell Factory ◽  
Ffa Metabolism

AbstractTo construct a superior microbial cell factory for chemical synthesis, a major challenge is to fully exploit cellular potential by identifying and engineering beneficial gene targets in sophisticated metabolic networks. Here, we take advantage of CRISPR interference (CRISPRi) and omics analyses to systematically identify beneficial genes that can be engineered to promote free fatty acids (FFAs) production in Escherichia coli. CRISPRi-mediated genetic perturbation enables the identification of 30 beneficial genes from 108 targets related to FFA metabolism. Then, omics analyses of the FFAs-overproducing strains and a control strain enable the identification of another 26 beneficial genes that are seemingly irrelevant to FFA metabolism. Combinatorial perturbation of four beneficial genes involving cellular stress responses results in a recombinant strain ihfAL−-aidB+-ryfAM−-gadAH−, producing 30.0 g L−1 FFAs in fed-batch fermentation, the maximum titer in E. coli reported to date. Our findings are of help in rewiring cellular metabolism and interwoven intracellular processes to facilitate high-titer production of biochemicals.

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