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.

Genes involved in lactose catabolism and organic acid production during growth of Lactobacillus delbrueckii UFV H2b20 in skimmed milk

2012 ◽  
Vol 3 (1) ◽  
pp. 23-32 ◽  
Author(s):  
A. Do Carmo ◽  
M. De Oliveira ◽  
D. Da Silva ◽  
S. Castro ◽  
A. Borges ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Organic Acid ◽  
Acid Production ◽  
Food Preservation ◽  
Starter Cultures ◽  
Lactobacillus Delbrueckii ◽  
Probiotic Properties ◽  
Organic Acid Production ◽  
Probiotic Lactobacillus ◽  
Skimmed Milk

There are three main reasons for using lactic acid bacteria (LAB) as starter cultures in industrial food fermentation processes: food preservation due to lactic acid production; flavour formation due to a range of organic molecules derived from sugar, lipid and protein catabolism; and probiotic properties attributed to some strains of LAB, mainly of lactobacilli. The aim of this study was to identify some genes involved in lactose metabolism of the probiotic Lactobacillus delbrueckii UFV H2b20, and analyse its organic acid production during growth in skimmed milk. The following genes were identified, encoding the respective enzymes: ldh – lactate dehydrogenase, adhE – Ldb1707 acetaldehyde dehydrogenase, and ccpA-pepR1 – catabolite control protein A. It was observed that L. delbrueckii UFV H2b20 cultivated in different media has the unexpected ability to catabolyse galactose, and to produce high amounts of succinic acid, which was absent in the beginning, raising doubts about the subspecies in question. The phylogenetic analyses showed that this strain can be compared physiologically to L. delbrueckii subsp. bulgaricus and L. delbrueckii subsp. lactis, which are able to degrade lactose and can grow in milk. L. delbrueckii UFV H2b20 sequences have grouped with L. delbrueckii subsp. bulgaricus ATCC 11842 and L. delbrueckii subsp. bulgaricus ATCC BAA-365, strengthening the classification of this probiotic strain in the NCFM group proposed by a previous study. Additionally, L. delbrueckii UFV H2b20 presented an evolutionary pattern closer to that of probiotic Lactobacillus acidophilus NCFM, corroborating the suggestion that this strain might be considered as a new and unusual subspecies among L. delbrueckii subspecies, the first one identified as a probiotic. In addition, its unusual ability to metabolise galactose, which was significantly consumed in the fermentation medium, might be exploited to produce low-browning probiotic Mozzarella cheeses, a desirable property for pizza cheeses.

GROWTH OF STAPHYLOCOCCUS AUREUS IN ACIDIFIED PASTEURIZED MILK1

1970 ◽  
Vol 33 (11) ◽  
pp. 516-520 ◽  
Author(s):  
T. E. Minor ◽  
E. H. Marth
Keyword(s):  
Staphylococcus Aureus ◽  
Acetic Acid ◽  
Lactic Acid ◽  
Hydrochloric Acid ◽  
Ph Value ◽  
The Other ◽  
Antagonistic Effects ◽  
Pasteurized Milk ◽  
Ph Values ◽  
Effect On Growth

The effect of gradually reducing the pH of pasteurized milk with acetic, citric, hydrochloric, lactic, and phosphoric acids over periods of 4, 8, and 12 hr on growth of Staphylococcus aureus 100 in this substrate was determined. In addition, 1: 1 mixtures of lactic acid and each of the other acids, and of acetic and citric acids were evaluated for their effect on growth of this organism. To achieve a 90% reduction in growth over a 12 hr period, a final pH value of 5.2 was required for acetic, 4.9 for lactic, 4.7 for phosphoric and citric, and 4.6 for hydrochloric acid. A 99% reduction during a 12 hr period was obtained with a final pH value of 5.0 for acetic, 4.6 for lactic, 4.5 for citric, 4.1 for phosphoric, and 4.0 for hydrochloric acid. A pH value of 3.3 was required for a 99.9% reduction with hydrochloric acid, whereas the same effect was produced at a pH value of 4.9 with acetic acid. Correspondingly lower pH values were required to inhibit growth within 8 and 4 hr periods. Mixtures of acids adjusted to pH values at the borderline for growth (12 hr period) exhibited neither synergistic nor antagonistic effects between two acids.

Control of Listeria monocytogenes on Frankfurters with Antimicrobials in the Formulation and by Dipping in Organic Acid Solutions

2004 ◽  
Vol 67 (11) ◽  
pp. 2456-2464 ◽  
Author(s):  
I. M. BARMPALIA ◽  
I. GEORNARAS ◽  
K. E. BELK ◽  
J. A. SCANGA ◽  
P. A. KENDALL ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Organic Acid ◽  
The United States ◽  
Acid Solutions ◽  
Overall Acceptability ◽  
Bactericidal Effects ◽  
Yeasts And Molds ◽  
And Storage

The antilisterial activity of sodium lactate (SL) and sodium diacetate (SD) was evaluated in a frankfurter formulation and in combination with a dipping treatment into solutions of lactic acid or acetic acid after processing and inoculation. Pork frankfurters were formulated with 1.8% SL or 0.25% SD or combinations of 1.8% SL with 0.25 or 0.125% SD. After processing, frankfurters were inoculated (2 to 3 log CFU/cm2) with a 10-strain composite of Listeria monocytogenes and left undipped or were dipped (2 min) in 2.5% solutions of lactic acid or acetic acid (23 ± 2°C) before vacuum packaging and storage at 10°C for 40 days. Total microbial populations and L. monocytogenes, lactic acid bacteria, and yeasts and molds were enumerated during storage. Sensory evaluations also were carried out on frankfurters treated and/or formulated with effective antimicrobials. The combination of 1.8% SL with 0.25% SD provided complete inhibition of L. monocytogenes growth throughout storage. Dipping in lactic acid or acetic acid reduced initial populations by 0.7 to 2.1 log CFU/cm2, but log CFU/cm2. For samples containing single antimicrobials and dipped in lactic acid or acetic acid, L. monocytogenes growth was completely inhibited or reduced over 12 and 28 days, respectively, whereas final populations were lower (P < 0.05) than those in undipped samples of the same formulations. Bactericidal effects during storage (reductions of 0.6 to 1.0 log CFU/cm2 over 28 to 40 days) were observed in frankfurters containing combinations of SL and SD that were dipped in organic acid solutions. Inclusion of antimicrobials in the formulation and/or dipping the product into organic acid solutions did not affect (P > 0.05) the flavor and overall acceptability of products compared with controls. The results of this study may be valuable to meat processors as they seek approaches for meeting new regulatory requirements in the United States.

scholarly journals Antagonistic action of Lactobacillus spp. against Staphylococcus aureus in cheese from Mompox - Colombia

2015 ◽  
Vol 68 (2) ◽  
pp. 7721-7727
Author(s):  
Piedad M. Montero Castillo ◽  
Antonio Díaz Caballero ◽  
Marlene Durán Lengua
Keyword(s):  
Staphylococcus Aureus ◽  
Lactic Acid ◽  
Pathogenic Bacteria ◽  
Antagonistic Activity ◽  
Food Preservation ◽  
Pathogenic Microorganisms ◽  
Bacterial Strains ◽  
Antagonistic Action ◽  
As Species ◽  
Chemical Products

In the food industry, food preservation techniques that do not use chemical products are becoming more common. Therefore, the aim of this research was to evaluate the antagonistic activity (antibiosis) of lactic-acid bacterial strains against pathogenic microorganisms. Lactic-acid bacterial strains were isolated from layered cheese and a commercial product (yogurt); and the same was done with pathogenic bacteria solely from layered cheese. The lactic-acid bacterial strains were identified as species from the Lactobacilli family, while the pathogenic bacteria from layered cheese were identified as Micrococcaceae family species (Staphylococcus aureus). Subsequently, in the same culture medium, bacteria of each species were sowed in order to determine the inhibitory activity ability of the Lactic Acid Bacteria (BAL) As a result, the highly antagonistic activity of the Lactobacilli (inhibition halos were larger than 0.5 centimeters in diameter) against isolated pathogenic microorganisms was demonstrated.

scholarly journals Treatment of Whole-Plant Corn Silage With Lactic Acid Bacteria and Organic Acid Enhances Quality by Elevating Acid Content, Reducing pH, and Inhibiting Undesirable Microorganisms

2020 ◽  
Vol 11 ◽  
Author(s):  
Fu-gui Jiang ◽  
Hai-jian Cheng ◽  
Dong Liu ◽  
Chen Wei ◽  
Wen-juan An ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Organic Acids ◽  
Organic Acid ◽  
Acid Content ◽  
Corn Silage ◽  
Fresh Material ◽  
Whole Plant ◽  
Lactic Acid Content

We investigated the variation in microbial community and fermentation characteristics of whole-plant corn silage after treatment with lactic acid bacteria (LAB) and organic acids. The fresh corn forages were treated with a combination of L. acidophilus and L. plantarum (106 CFU/g fresh material) or a 7:1:2 ratio of formic acid, acetic acid, and propionic acid (6 mL/g fresh material) followed by 45 or 90 days of ensiling. Silages treated with LAB showed increased lactic acid content and decreased pH after 45 days. Although treatment with LAB or organic acids decreased the common and unique operational taxonomic units, indicating a reduction in microbial diversity, the relative abundance of Lactobacillus was elevated after 45 and 90 days compared with control, which was more distinct in the organic acid groups. Moreover, we found higher levels of acetic acid and increased abundance of Acetobacter in silages treated with organic acids whereas undesirable microorganisms such as Klebsiella, Paenibacillus, and Enterobacter were reduced. In summary, the quality of corn silages was improved by LAB or organic acid treatment in which LAB more effectively enhanced lactic acid content and reduced pH while organic acid inhibited the growth of undesirable microorganisms.

Osmoadaptation by Staphylococcus aureus: Analysis of Several Strains Linked to Food Poisoning Outbreaks

1997 ◽  
Vol 60 (2) ◽  
pp. 139-143 ◽  
Author(s):  
HEATHER A. LOUCH ◽  
MICHELLE L. ECK ◽  
KAREN J. MILLER
Keyword(s):  
Staphylococcus Aureus ◽  
Glycine Betaine ◽  
Food Poisoning ◽  
Growth Conditions ◽  
Aureus Strain ◽  
Resonance Spectroscopy ◽  
Genetic Studies ◽  
Cell Extracts ◽  
Amino Acid Analyzer ◽  
Solute Composition

The authors examined the intracellular solute composition of five strains of Staphylococcus aureus after growth in a medium of low water activity. Organic solutes within cell extracts were analyzed using an amino acid analyzer and nuclear magnetic resonance spectroscopy. Intracellular potassium content was assayed using a potassium-specific electrode. The results showed that the five S. aureus strains accumulated proline and glycine betaine intracellularly under these growth conditions. The levels of accumulated proline and glycine betaine were strikingly similar among the strains, despite differences in salt tolerance. During the course of these experiments it was also found that S. aureus strain RN4220 (a strain commonly used in genetic studies) was selectively impaired in its ability to utilize proline during osmoadaptation at 41°C.

scholarly journals Contribution of Lactococcus lactis Reducing Properties to the Downregulation of a Major Virulence Regulator in Staphylococcus aureus, theagrSystem

2014 ◽  
Vol 80 (22) ◽  
pp. 7028-7035 ◽  
Author(s):  
Sébastien Nouaille ◽  
Lucie Rault ◽  
Sophie Jeanson ◽  
Pascal Loubière ◽  
Yves Le Loir ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Lactic Acid ◽  
Lactococcus Lactis ◽  
Response Regulator ◽  
Food Poisoning ◽  
Accessory Gene ◽  
Content Type ◽  
Accessory Gene Regulator ◽  
Virulence Regulator ◽  
Reducing Properties

ABSTRACTStaphylococcus aureusis a major cause of food poisoning outbreaks associated with dairy products, because of the ingestion of preformed enterotoxins. The biocontrol ofS. aureususing lactic acid bacteria (LAB) offers a promising opportunity to fight this pathogen while respecting the product ecosystem. We had previously established the ability ofLactococcus lactis, a lactic acid bacterium widely used in the dairy industry, to downregulate a major staphylococcal virulence regulator, the accessory gene regulator (agr) system, and, as a consequence,agr-controlled enterotoxins. In the present paper, we have shown that the oxygen-independent reducing properties ofL. lactiscontribute toagrdownregulation. Neutralizing lactococcal reduction by adding potassium ferricyanide or maintaining the oxygen pressure constant at 50% releasedagrdownregulation in the presence ofL. lactis. This downregulation still occurred in anS. aureus srrAmutant, indicating that the staphylococcal respiratory response regulator SrrAB was not the only component in the signaling pathway. Therefore, this study clearly demonstrates the ability ofL. lactisreducing properties to interfere with the expression ofS. aureusvirulence, thus highlighting this general property of LAB as a lever to control the virulence expression of this major pathogen in a food context and beyond.

scholarly journals Growth behavior and temporal enterotoxin D expression of Staphylococcus aureus strains under glucose and lactic acid stress

Food Control ◽  
2016 ◽  
Vol 62 ◽  
pp. 69-73 ◽  
Author(s):  
Henna-Maria Sihto ◽  
Taurai Tasara ◽  
Roger Stephan ◽  
Sophia Johler
Keyword(s):  
Staphylococcus Aureus ◽  
Lactic Acid ◽  
Acid Stress ◽  
Growth Behavior

scholarly journals Intracellular pH Response to Weak Acid Stress in Individual Vegetative Bacillus subtilis Cells

2016 ◽  
Vol 82 (21) ◽  
pp. 6463-6471 ◽  
Author(s):  
Rachna Pandey ◽  
Norbert O. E. Vischer ◽  
Jan P. P. M. Smelt ◽  
Johan W. A. van Beilen ◽  
Alexander Ter Beek ◽  
...  
Keyword(s):  
Organic Acid ◽  
Single Cell ◽  
Acid Stress ◽  
Weak Acid ◽  
Food Preservation ◽  
Cell Level ◽  
Food Preservatives ◽  
Content Type ◽  
Weak Organic Acid ◽  
Weak Acid Stress

ABSTRACTIntracellular pH (pHi) critically affects bacterial cell physiology. Hence, a variety of food preservation strategies are aimed at perturbing pHihomeostasis. Unfortunately, accurate pHiquantification with existing methods is suboptimal, since measurements are averages across populations of cells, not taking into account interindividual heterogeneity. Yet, physiological heterogeneity in isogenic populations is well known to be responsible for differences in growth and division kinetics of cells in response to external stressors. To assess in this context the behavior of intracellular acidity, we have developed a robust method to quantify pHiat single-cell levels inBacillus subtilis. Bacilli spoil food, cause disease, and are well known for their ability to form highly stress-resistant spores. Using an improved version of the genetically encoded ratiometric pHluorin (IpHluorin), we have quantified pHiin individualB. subtiliscells, cultured at an external pH of 6.4, in the absence or presence of weak acid stresses. In the presence of 3 mM potassium sorbate, a decrease in pHiand an increase in the generation time of growing cells were observed. Similar effects were observed when cells were stressed with 25 mM potassium acetate. Time-resolved analysis of individual bacteria in growing colonies shows that after a transient pH decrease, long-term pH evolution is highly cell dependent. The heterogeneity at the single-cell level shows the existence of subpopulations that might be more resistant and contribute to population survival. Our approach contributes to an understanding of pHiregulation in individual bacteria and may help scrutinizing effects of existing and novel food preservation strategies.IMPORTANCEThis study shows how the physiological response to commonly used weak organic acid food preservatives, such as sorbic and acetic acids, can be measured at the single-cell level. These data are key to coupling often-observed single-cell heterogeneous growth behavior upon the addition of weak organic acid food preservatives. Generally, these data are gathered in the form of plate counting of samples incubated with the acids. Here, we visualize the underlying heterogeneity in cellular pH homeostasis, opening up avenues for mechanistic analyses of the heterogeneity in the weak acid stress response. Thus, microbial risk assessment can become more robust, widening the scope of use of these well-known weak organic acid food preservatives.

Sign in / Sign up

Export Citation Format

Share Document