Antibacterial activity of Carnobacterium spp. from meats

Introduction: Carnobacterium maltaromaticum and C. divergens are frequently predominant among microbiota on chilled vacuum-packaged (VP) meats. Due to the potential of producing antibacterial compounds, the two species may be used as protective cultures to extend the storage life of VP meat and improve meat safety.

Purpose: To investigate the inhibitory activity of 15 strains of Carnobacterium spp. obtained from chilled VP meat on the growth of spoilage associated bacteria and pathogenic bacteria under chilled anaerobic conditions.

Methods: The inhibitory activity of three strains of C. maltaromaticum and 12 strains of C. divergens which had been identified by whole genome sequencing analysis from previous study were selected. The target bacteria included both spoilage associated bacteria and pathogenic bacteria, i.e. the same 15 strains of Carnobacterium spp., four Hafnia, four Rhanella, six Serratia, three Yersinia, 13 pathogenic Escherichia coli of different serotypes, two Salmonella spp. and one Listeria monocytogenes. Inhibitory activity was tested on tryptone soya agar incubated in an anaerobic jar at 10oC for 5 days, and was determined as positive when an inhibition zone was present.

Results: Two C. maltaromaticum and three C. divergens strains showed inhibitory activity, respectively. Target bacteria sensitive to the inhibitory strains were all Gram-positive bacteria. C. maltaromaticum A5 showed the widest inhibition spectrum, by inhibiting 13 Carnobacterium spp. and L. monocytogenes, followed by C. maltaromaticum A7, which showed inhibition on the growth of seven Carnobacterium spp.

Significance: The five strains of Carnobacteirum spp., in particular, C. maltaromaticum A5 and A7 can be explored as protective cultures in the future.