The pepR gene of Lactobacillus sakei is positively regulated by anaerobiosis at the transcriptional level

Abstract

Lactobacillus sakei is a lactic acid bacterium belonging to the natural flora of meat products. It constitutes the main flora of vacuum-packed meat and is largely used in western Europe as a starter for the manufacturing of fermented sausages. This species is able to grow both under aerobiosis and anaerobiosis. In many technological processes involving it, oxygen is scarce. The aim of this study was to identify the major proteins affected by growth under anaerobiosis. Using two-dimensional electrophoresis, we showed that one spot was 10-fold overexpressed when cells were grown under anaerobiosis. By N-terminal sequencing it was identified as a peptidase (PepR), and the pepR gene was cloned. Northern analysis revealed that pepR was expressed as a single 1.27-kb transcript induced under anaerobiosis. A mutant was constructed by single crossover in the pepR gene, and its growth and survival were not affected by anaerobiosis.

FIG. 1.

Portions of two-dimensional gels showing expression of PepR of L. sakei under aerobiosis (a) and under anaerobiosis (b). The arrows indicate the position of PepR. Proteins were extracted from early-stationary-phase cells.

FIG. 2.

Schematic representation of the pepR encoding region. The insert of plasmid pRV415 and putative transcription terminators are shown.

FIG. 3.

Transcriptional analysis of pepR of L. sakei under anaerobiosis (lane a) and under aerobiosis (lane b).