文摘

The genus Listeria includes eight different species, but only Listeria monocytogenes is associated to human illness. This microorganism is capable of growing in temperatures ranging from 4?°C to 37?°C and forming biofilms on processing sites, which is of great concern in the food industry. In this current work, the transcription of genes related to biofilm formation, stress-response, and virulence in two strains of L. monocytogenes, serotypes 1/2a and 4b, growing at 7?°C and 37?°C, was analyzed by quantitative real time PCR (qPCR). For both serotypes, a temperature of 7?°C significantly increased (P--.05) the transcription level of sigB, prfA, luxS, sufS, sufU, ltrC and flaA genes when compared to growth at 37?°C, whereas transcription of the hly gene did not vary significantly at the temperatures tested. Incubation at 7?°C increased the transcriptional level of the actA gene only in L. monocytogenes serotype 1/2a. On the other hand, L. monocytogenes serotype 4b showed significantly increased transcription of the degU gene at 7?°C. Interestingly, expression of the agrA gene, which is involved in adhesion and biofilm formation on abiotic surfaces, was not detected in serotype 4b, and its transcription level was lower at 7?°C in serotype 1/2a. These results demonstrate that the two studied L. monocytogenes serotypes, which are responsible for many human listeriosis cases, have different molecular mechanisms at temperatures of 7?°C and 37?°C.