Molecular characterisation and biomass and metabolite production of Lactobacillus reuteri LPB P01-001: a potential probiotic

Lactobacillus reuteri LPB P01-001 was isolated from the gastrointestinal tract of wild swine and was characterised by biochemical testing and sequencing of gene 16S rRNA. A simple and low-cost culture medium based on cane sugar (2.5% p/v) and yeast extract (1% p/v) was used in the production of this probiotic. The fermentative conditions were a) pH control at 6.5 and b) no pH control; both were set at 37°C in a 12 L slightly stirred tank bioreactor. Fermentation parameters such as the specific growth rate, productivity and yield of biomass, lactic and acetic acid levels were determined. L. reuteri LPB P01-001 behaves as an aciduric bacteria because it grows better in a low pH medium without pH control. However, the lactic acid production yield was practically half (9.22 g.L-1) of that obtained under a constant pH of 6.5, which reached 30.5 g.L-1 after 28 hours of fermentation. The acetic acid production was also higher under pH-controlled fermentation, reaching 10.09 g.L-1 after 28 hours of fermentation. These parameters may raise the interest of those committed to the efficient production of a probiotic agent for swine.

Effect of refrigeration and frozen storage on the campylobacter jejuni recovery from naturally contaminated broiler carcasses

Campylobacter jejuni is the most common thermophilic Campylobacter associated with human enteritis in many countries. Broilers and their by-products are the main sources for human enteritis. Refrigeration and freezing are used to control bacterial growth in foods. The effect of these interventions on survival of Campylobacter jejuni is yet not quite understood. This study evaluated the effect of storage temperature on the survival of C. jejuni in chicken meat stored for seven days at 4ºC and for 28 days at -20ºC. The influence of selective enrichment on recovery of Campylobacter was also evaluated. Thirty fresh chicken meat samples were analyzed and 93.3 percent was contaminated with termotolerant Campylobacter spp. with average count of 3.08 Log10 CFU/g on direct plating. After refrigeration, 53.3 percent of the analyzed samples tested positive for Campylobacter and the average count was 1.19 Log10 CFU/g. After storage at -20ºC, 36.6 percent of the samples were positive with a verage count of 0.75 Log10 CFU/g. C. jejuni was detected after enrichment, respectively, in 50 percent of the fresh, 36.7 percent of the refrigerated and 33.3 percent of the frozen meat samples analyzed. No difference was detected for the recovery of C. jejuni from fresh, refrigerated or frozen samples after selective enrichment, showing that this microorganism can survive under the tested storage conditions.