Abstract:
Lactic acid bacteria (LAB) encompass several genera and numerous species that have been
investigated extensively mainly due to their beneficial effect on human health. Carnobacterium
maltaromaticum is a facultative anaerobic, gram-positive, rod-shaped lactic acid bacterium. It has
been known to colonize range of habitats including dairy, meat and fish and has been isolated from
vacuum-packed fish and meat products and live fish too. Studies have suggested that C.
maltaromaticum strains can be applied as bio-preservative agents in food products due to its
production of antimicrobial compounds, bacteriocins, which can inhibit foodborne pathogen
Listeria monocytogenes. C. maltaromaticum strains can also be used as potential probiotic culture
in aquaculture except for some, which have been identified as putative virulent strains. In present
study, pan-genome approach was adopted to perform intraspecies genome analysis. Results
suggested that dairy strains have larger genome size, higher percentage of pseudogenes and higher
percentage of genomic islands that leads to a hypothesis that dairy strains may be acquiring genes
beneficial for adaptation in dairy niche and shedding those genes that might be either virulent or
not necessary for the bacterium. BRIG analysis revealed acquisition of three genomic islands
common to dairy isolated strains only. Most of the acquired genes encodes for metabolic proteins,
for instance, lactose and galactose metabolism genes, genes for hydrolytic activity and osmotic
stress maintenance genes. Regarding safety aspect analysis, virulent factors were identified which
proposed presence of ̴ 40 VFs not present in five established probiotic strains. Among those 40
VFs, dairy strains possess lowest and fish isolated strain ATCC35586 encodes highest. Antibiotic
resistance genes were not identified in any strain while Bacteriocin prediction analysis showed
presence of four bacteriocins in a meat-isolated strain DSM20722 and 3 bacteriocins in two dairy isolated strains LMA28 and DSM20342MX
