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The bacteriocin-producing Lactobacillus plantarum BFE 5092 was assessed for its potential as a protective culture in the biopreservation of aerobically stored turkey meat. This strain produces three bacteriocins, i.e. plantaricins EF, JK and N. The absolute expression of Lactobacillus plantarum BFE 5092 16S rRNA housekeeping gene, as well as l-ldh, plnEF and plnG genes as determined by quantitative, real-time-PCR, revealed that these genes were expressed to similar levels when the strain was grown at 8 and 30 °C in MRS broth. On turkey meat, Lactobacillus plantarum BFE 5092 did not grow but survived, as indicated by similar viable cell numbers during a 9-day storage period at 8 °C. When inoculated at 1 × 10(7) CFU/g on the turkey meat and subsequently stored at 10 °C, the culture did again not show good growth. Lactobacillus plantarum BFE 5092 could not inhibit the growth of naturally occurring listeriae or Gram-negative bacteria on the turkey meat at 10 °C, or that of Listeria monocytogenes when it was co-inoculated at a level of 1 × 10(5) CFU/g. Gene expression analyses showed that the bacteriocin genes were expressed on turkey meat stored at 10 °C. Moreover, the investigation into the absolute expression of the three plantaricin genes of Lactobacillus plantarum BFE 5092 in co-culture with Listeria monocytogenes on turkey meat by qRT-PCR showed that the plantaricin genes were indeed expressed during the low-temperature storage condition. The Lactobacillus plantarum BFE 5092 strain overall could not effectively inhibit L. monocytogenes and therefore it would not make a suitable protective culture for biopreservation of turkey meat stored aerobically at low temperature.

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Two putative adhesion genes of the potentially probiotic strain Lactobacillus plantarum BFE 5092, i.e., a gene with similarity to an aggregation-promoting factor gene apf5092, and the mucin-binding protein gene mub5092, were investigated in this study. The gene encoding apf5092 encoded a protein bearing a predicted 26 amino acid signal peptide and a LysM domain putatively involved in binding to peptidoglycan. Moreover, the deduced protein also showed an amino acid sequence characteristic of an aggregation-promoting factor. The genes were tested for expression under different environmental conditions, and transcriptional studies on apf5092 showed that the expression could be influenced by low temperature and pH within 30 min. The aggregation behavior of the cells also changed at the low pH condition, but less noticeably at low temperature. To further investigate the role of apf5092 in aggregation, it was cloned and expressed in E. coli. The transformed strain showed higher co-aggregation ability with Gram-positive bacteria. Transcription studies on mub5092 revealed that it could be induced by mucin when added to the growth medium within 30 min. The data suggested that L. plantarum BFE 5092 can quickly adapt to changing environmental conditions and that enhanced aggregation may be important to survive low pH conditions, e.g., of the stomach or of fermented foods, and may thus be an important colonization factor.