Molecular Ecology of
            <i>Listeria monocytogenes</i>
            : Evidence for a Reservoir in Milking Equipment on a Dairy Farm

Latorre, Alejandra A.; Kessel, Jo Ann S. Van; Karns, Jeffrey S.; Zurakowski, Michael J.; Pradhan, Abani K.; Zadoks, Ruth N.; Boor, Kathryn J.; Schukken, Y.H.

doi:10.1128/aem.01826-08

Cited by 79 publications

(104 citation statements)

References 37 publications

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“…The pathogen is largely spread in the environment. It has been isolated from water systems (2-4), vegetation (5), soil (6)(7)(8), farms (9)(10)(11)(12), food industries (13)(14)(15), and the feces of animals (16)(17)(18). Environmental adaptation requires that the cell have the ability to integrate environmental cues in order to adapt its physiology to the surrounding conditions through the regulation of gene expression.…”

mentioning

confidence: 99%

Survival of Listeria monocytogenes in Soil Requires AgrA-Mediated Regulation

Vivant

Garmyn

Gal

et al. 2015

Appl Environ Microbiol

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In this study, we investigated whether the Agr-mediated response is triggered during adaptation in soil, and we compared survival patterns in a set of 10 soils. The fate of the parental strain L. monocytogenes L9 (a rifampin-resistant mutant of L. monocytogenes EGD-e) and that of a ⌬agrA deletion mutant were compared in a collection of 10 soil microcosms. The ⌬agrA mutant displayed significantly reduced survival in these biotic soil microcosms, and differential transcriptome analyses showed large alterations of the transcriptome when AgrA was not functional, while the variations in the transcriptomes between the wild type and the ⌬agrA deletion mutant were modest under abiotic conditions. Indeed, in biotic soil environments, 578 protein-coding genes and an extensive repertoire of noncoding RNAs (ncRNAs) were differentially transcribed. The transcription of genes coding for proteins involved in cell envelope and cellular processes, including the phosphotransferase system and ABC transporters, and proteins involved in resistance to antimicrobial peptides was affected. Under sterilized soil conditions, the differences were limited to 86 genes and 29 ncRNAs. These results suggest that the response regulator AgrA of the Agr communication system plays important roles during the saprophytic life of L. monocytogenes in soil. Listeria monocytogenes is the causative agent of listeriosis, a serious foodborne infection affecting essentially immunocompromised individuals, the elderly, and pregnant women (1). The pathogen is largely spread in the environment. It has been isolated from water systems (2-4), vegetation (5), soil (6-8), farms (9-12), food industries (13-15), and the feces of animals (16-18). Environmental adaptation requires that the cell have the ability to integrate environmental cues in order to adapt its physiology to the surrounding conditions through the regulation of gene expression. Genomics showed that an important part of the L. monocytogenes genome (7.3%) is dedicated to regulation and includes 209 transcriptional regulators, 15 histidine kinases, and 16 response regulators constituting two-component systems (19). Two-component systems participate in the ability of bacteria to sense and respond to fluctuating environmental conditions. AgrC/AgrA is a two-component regulatory system that is part of the Agr communication system. Initially described in Staphylococcus aureus, this communication system is organized as a four-gene operon, agrBDCA. AgrB is a membrane-bound protein that processes the propeptide AgrD into a mature autoinducing peptide (AIP). Detection of AIP by the histidine kinase AgrC induces transcriptional regulation through activation of the regulator AgrA. Detailed data concerning the role of the Agr system in the physiology of S. aureus are available (20)(21)(22). So far, its role in the adaptation of L. monocytogenes to its environment is only partially understood (23). Reports show that the Agr communication system of L. monocytogenes is involved in adhesion to abiotic surfaces (24) in ...

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mentioning

confidence: 99%

Survival of Listeria monocytogenes in Soil Requires AgrA-Mediated Regulation

Vivant

Garmyn

Gal

et al. 2015

Appl Environ Microbiol

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“…Despite the high cost of milking machine, it is highly effective and helpful to produce clean milk without any direct contact with the farmers and the surroundings. On the contrary Latorre et al, 2009 concluded that the milking machine was the most likely source of contamination.…”

Section: Resultsmentioning

confidence: 95%

“…Regardless of the source of contamination, it is important to note that results of this and previous studies (Latorre, et al, 2009 andPantoja, et al, 2012) demonstrate that farms can develop persistent sources of BTM contamination with L. monocytogenes. Therefore, longitudinal screening of BTM and dairy environment could be valuable for programs developed to improve the safety of milk.…”

Section: Resultsmentioning

confidence: 98%

“…Environmental and BTM milk samples were processed as described by (Latorre et al, 2009). Silage, bedding and fecal samples (50 grams) were mixed with 200 ml of peptone water in two-chamber filter bags.…”

Section: Preparation Of Samplesmentioning

confidence: 99%

“…L. monocytogenes is present the dairy farm environment and can survive in the gastrointestinal tract of cows, thus constituting a source of contamination of bulk tank milk (BTM) (Latorre et al, 2009). Listeria monocytogenes is capable of multiplying at temperatures ≤7°C and surviving in environments with a wide range of pH values (4.3 to 10) and high salt concentrations (Ryser, 2001).…”

mentioning

confidence: 99%

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