A genome guided evaluation of the Lab4 probiotic consortium.

Draft genome sequences of the Lab4 probiotic consortium were deposited in Genbank: Bifidobacterium animalis subsp lactis CUL34 (PRJNA482550), Bifidobacterium bifidum CUL20 (PRJNA559984), Lactobacillus acidophilus CUL60 (PRJNA482335), Lactobacillus acidophilus CUL21 (PRJNA482434). Probiogenomic analyses confirmed existing taxonomies and identified putative gene sequences that were functionally related to the performance of each organism during in vitro assessments of bile and acid tolerability, adherence to enterocytes and susceptibility to antibiotics. Genomic stability predictions identified no significant risk of gene acquisition of both antibiotic resistance and virulence genes. These observations were supported by acute phase and repeat dose tolerability studies in Wistar rats. High doses of Lab4 did not result in mortalities, clinical/histopathological abnormalities nor systemic toxicity. Increased faecal numbers of Lab4 in supplemented rats implied survival through the gastrointestinal tract and/or impact the intestinal microbiota composition. In summary, this study provides multifaceted support for probiotic functionality and the safety of the Lab4 consortium.

Streptomyces coelicolor Dps-like proteins: differential dual roles in response to stress during vegetative growth and in nucleoid condensation during reproductive cell division.

The Dps protein, a member of the ferritin family, contributes to DNA protection during oxidative stress and plays a central role in nucleoid condensation during stationary phase in unicellular eubacteria. Genome searches revealed the presence of three Dps-like orthologues within the genome of the Gram-positive bacterium Streptomyces coelicolor. Disruption of the S. coelicolor dpsA, dpsB and dpsC genes resulted in irregular condensation of spore nucleoids in a gene-specific manner. These irregularities are correlated with changes to the spacing between sporulation septa. This is the first example of these proteins playing a role in bacterial cell division. Translational fusions provided evidence for both developmental control of DpsA and DpsC expression and their localization to sporogenic compartments of aerial hyphae. In addition, various stress conditions induced expression of the Dps proteins in a stimulus-dependent manner in vegetative hyphae, suggesting stress-induced, protein-specific protective functions in addition to their role during reproductive cell division. Unlike in other bacteria, the S. coelicolor Dps proteins are not induced in response to oxidative stress.