Responses of Listeria monocytogenes to acid stress and glucose availability monitored by measurements of intracellular pH and viable counts

Shabala, Lana; Budde, B.B.; Ross, Tom; Siegumfeldt, Henrik; McMeekin, TA

doi:10.1016/s0168-1605(01)00740-1

Cited by 46 publications

(52 citation statements)

References 33 publications

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“…The removal of glucose from simulated gastric juice caused a dramatic loss of viability that was up to 4 log 10 CFU ml Ϫ1 greater than that observed by Charalampopoulos et al (7), who previously determined that glucose can increase the survival of lactobacilli in acid environments over 4 h of exposure. Under acidic conditions, the intracellular pH was higher in cells in a medium containing glucose at lower extracellular pH values, indicating that glucose plays a significant role in homeostasis (48). Small reductions in viability occurred among cultures devoid of lysozyme and CaCl 2 (Fig.…”

Section: Discussionmentioning

confidence: 93%

“…In addition, Shabala et al (48) also noted that increased bacterial survival is directly proportional to glucose availability in the media. It was postulated that the increased glucose availability met the high energy demands of maintaining pH homeostasis (48). We further linked the relationship between the survival of L. rhamnosus GG in the presence of glucose and its ability to utilize sugars.…”

Section: Discussionmentioning

confidence: 99%

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Survival of Probiotic Lactobacilli in Acidic Environments Is Enhanced in the Presence of Metabolizable Sugars

Corcoran

Stanton

Fitzgerald

et al. 2005

Appl Environ Microbiol

434

257

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Lactobacillus rhamnosus GG is an industrially significant probiotic strain with proven health benefits. In this study, the effect of glucose on L. rhamnosus GG survival was analyzed in simulated gastric juice at pH 2.0. It was found that the presence of 19.4 mM glucose resulted in up to 6-log 10 -enhanced survival following 90 min of exposure. Further work with dilute HCl confirmed that glucose was the sole component responsible. Comparative analysis with other Lactobacillus strains revealed that enhanced survival was apparent in all strains, but at different pH values. The presence of glucose at concentrations from 1 to 19.4 mM enhanced L. rhamnosus GG survival from 6.4 to 8 log 10 CFU ml ؊1 in simulated gastric juice. The mechanisms behind the protective effect of glucose were investigated. Addition of N,N-dicyclohexylcarbodiimide to simulated gastric juice caused survival to collapse, which was indicative of a prominent role in inhibition of F 0 F 1 -ATPase. Further work with neomycin-resistant mutants that exhibited 38% to 48% of the F 0 F 1 -ATPase activity of the parent confirmed this, as the survival in the presence of glucose of these mutants decreased 3 ؋ 10 6 -fold compared with the survival of the wild type (which had a viability of 8.02 log 10 CFU ml ؊1 ). L. rhamnosus GG survival in acidic conditions occurred only in the presence of sugars that it could metabolize efficiently. To confirm the involvement of glycolysis in the glucose effect, iodoacetic acid was used to inhibit glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity. The reduction in GAPDH activity caused survival to decrease by 8.30 log 10 CFU ml ؊1 in the presence of glucose. The data indicate that glucose provides ATP to F 0 F 1 -ATPase via glycolysis, enabling proton exclusion and thereby enhancing survival during gastric transit.

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Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Survival of Probiotic Lactobacilli in Acidic Environments Is Enhanced in the Presence of Metabolizable Sugars

Corcoran

Stanton

Fitzgerald

et al. 2005

Appl Environ Microbiol

434

257

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“…FRIM enables studies of dynamic changes with high sensitivity and on the single-cell level in important physiological parameters: e.g., intracellular pH (pH i ). Listeria maintains its pH i within a narrow range of 7.6 to 8 at extracellular pH (pH ex ) values of 5.0 to 8.0 (4,25) and at pH ex 4.0 with the presence of glucose (23). It is believed that viable cells need to maintain a transmembrane pH gradient with their pH i above the pH ex , and failure to maintain pH i homeostasis indicates that the bacterial cell is severely stressed and ultimately leads to loss of cell viability.…”

mentioning

confidence: 99%

“…It is believed that viable cells need to maintain a transmembrane pH gradient with their pH i above the pH ex , and failure to maintain pH i homeostasis indicates that the bacterial cell is severely stressed and ultimately leads to loss of cell viability. FRIM has been used to determine the pH i of L. monocytogenes after exposure to osmotic and acid stress (7,23). Also, the dissipation of the pH gradient in L. monocytogenes after exposure to different bacteriocins has been determined with FRIM (4, 12).…”

mentioning

confidence: 99%

Response of Listeria monocytogenes to Disinfection Stress at the Single-Cell and Population Levels as Monitored by Intracellular pH Measurements and Viable-Cell Counts

Kastbjerg

Nielsen

Arneborg

et al. 2009

Appl Environ Microbiol

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Listeria monocytogenes has a remarkable ability to survive and persist in food production environments. The purpose of the present study was to determine if cells in a population of L. monocytogenes differ in sensitivity to disinfection agents as this could be a factor explaining persistence of the bacterium. In situ analyses of Listeria monocytogenes single cells were performed during exposure to different concentrations of the disinfectant Incimaxx DES to study a possible population subdivision. Bacterial survival was quantified with plate counting and disinfection stress at the single-cell level by measuring intracellular pH (pH i ) over time by fluorescence ratio imaging microscopy. pH i values were initially 7 to 7.5 and decreased in both attached and planktonic L. monocytogenes cells during exposure to sublethal and lethal concentrations of Incimaxx DES. The response of the bacterial population was homogenous; hence, subpopulations were not detected. However, pregrowth with NaCl protected the planktonic bacterial cells during disinfection with Incimaxx (0.0015%) since pH i was higher (6 to 6.5) for the bacterial population pregrown with NaCl than for cells grown without NaCl (pH i 5 to 5.5) (P < 0.05). The protective effect of NaCl was reflected by viable-cell counts at a higher concentration of Incimaxx (0.0031%), where the salt-grown population survived better than the population grown without NaCl (P < 0.05). NaCl protected attached cells through drying but not during disinfection. This study indicates that a population of L. monocytogenes cells, whether planktonic or attached, is homogenous with respect to sensitivity to an acidic disinfectant studied on the single-cell level. Hence a major subpopulation more tolerant to disinfectants, and hence more persistent, does not appear to be present.

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“…These observations highlight the importance of in situ investigations of bacteriocins and their target organisms, as demonstrated in the present study. Previously, FRIM has been used to measure pH i in L. monocytogenes (9,37), Bacillus licheniformis (23), Candida krusei, and Saccharomyces cerevisiae (22), as well as lactic acid bacteria (38), on solid surfaces such as membrane filters or poly-L-lysine-coated glass slides. In the present study, FRIM was successfully applied for measuring pH i directly on the surface of meat sausages, and in the future these in situ measurements may advantageously be performed on other food surfaces.…”

Section: Discussionmentioning

confidence: 99%

Two Subpopulations of Listeria monocytogenes Occur at Subinhibitory Concentrations of Leucocin 4010 and Nisin

Hornbæk¹,

Brockhoff

Siegumfeldt³

et al. 2006

Appl Environ Microbiol

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Responses of Listeria monocytogenes to acid stress and glucose availability monitored by measurements of intracellular pH and viable counts

Cited by 46 publications

References 33 publications

Survival of Probiotic Lactobacilli in Acidic Environments Is Enhanced in the Presence of Metabolizable Sugars

Survival of Probiotic Lactobacilli in Acidic Environments Is Enhanced in the Presence of Metabolizable Sugars

Response of Listeria monocytogenes to Disinfection Stress at the Single-Cell and Population Levels as Monitored by Intracellular pH Measurements and Viable-Cell Counts

Two Subpopulations of Listeria monocytogenes Occur at Subinhibitory Concentrations of Leucocin 4010 and Nisin

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