Boosting the growth of the probiotic strain Lactobacillus paracasei ssp. paracasei F19.

Single so-called booster substances were added to the fermentation medium of the probiotic strain Lactobacillus (L.) paracasei ssp. paracasei F19 to enhance its growth. A wide screening was carried out in microtiter plates and a statistical analysis of the growth parameters was performed. CFU counts were used to correlate the increase in OD590nm with the increase in viable cell number. Sodium ascorbate, sodium pyruvate, manganese sulfate and cysteine had a remarkable boosting effect on the growth of L. paracasei F19. Three of the boosters increased the growth rate of the strain and led to a higher cell density and biomass yield in laboratory conditions. Cysteine significantly shortened the lag phase, therefore reducing the fermentation times. The boosters were tested on four additional Lactobacillus species and their growth boosting activity was retained. To investigate whether the growth boosters could improve the tolerance of L. paracasei F19 to the adverse condition in the GI tract, additional tests were performed. Sodium ascorbate and sodium pyruvate exerted a certain antioxidant effect, as they improved the tolerance of L. paracasei F19 to H2O2. Sodium ascorbate enhanced the growth of the strain in low pH.

Lactobacillus insicii sp. nov., isolated from fermented raw meat.

The analysis of the bacterial microbiota of retain samples of pork salami revealed an isolate (strain TMW 1.2011T) that could neither be assigned to typical genera of starter organisms nor to any other known meat-associated species. Cells were Gram-stain-positive, short, straight rods occurring singly, in pairs or short chains. Phylogenetic analysis of the 16S rRNA gene sequence and specific phenotypic characteristics showed that strain TMW 1.2011T belonged to the phylogenetic Lactobacillus alimentarius group, and the closest neighbours were Lactobacillus nodensis JCM 14932T (97.8 % 16S rRNA gene sequence similarity), Lactobacillus tucceti DSM 20183T (97.4 %), 'Lactobacillus ginsenosidimutans' EMML 3041 (97.3 %), Lactobacillus versmoldensis DSM 14857T (96.9 %) and Lactobacillus furfuricola JCM 18764T (97.2 %). Similarities using partial gene sequences of the alternative chronometers pheS, dnaK and rpoA also support these relationships. DNA-DNA relatedness between the novel isolate and L. nodensis JCM 14932T, L. versmoldensis DSM 14857T and L. tucceti DSM 20183T, L. furfuricola JCM 18764T and 'L. ginsenosidimutans' EMML 3041 were below 70 % and the DNA G+C content was 36.3 mol%. The cell-wall peptidoglycan type is l-Lys-Gly-d-Asp. Based on phylogenetic, chemotaxonomic and physiological evidence, strain TMW 1.2011T represents a novel species of the genus Lactobacillus, for which the name Lactobacillus insicii sp. nov. is proposed. The type strain is TMW 1.2011T ( = CECT 8802T = DSM 29801T).