Dados do Trabalho

Título

Bacteriocinogenic Latilactobacillus curvatus ST0403 strain: A promising bio-protective culture for control of Listeria monocytogenes

Introdução

Lactic acid bacteria (LAB) are known for their production of bacteriocins, defined as
ribosomal synthesized polypeptides, antagonistic to genetically related organisms. However,
safety assessment of LAB is an essential mission in the selection of the strains dedicated to being
applied as commercial beneficial cultures.

Material e Métodos

Ltb. curvatus ST0403 was isolated from Bulgarian white brine cheese and identified
based on its biochemical and genetic characteristics, including 16S rRNA sequencing. Produced
bacteriocin was characterized, including behavior of antimicrobial peptides in selected pH (2.0–
10.0), temperatures (10°C-121°C), presence of chemicals applied in food processing
developments. Bacteriocin activity was assessed against different enterococci, lactobacilli, and
listeria strains. Bacterial growth of strain ST0403 was monitored spectrophotometrically in MRS
broth at 37°C for 24h; production of bacteriocin was evaluated against strains of L.
monocytogenes. Mode of action for studied bacteriocins was evaluated versus L. monocytogenes
strains.

Resultados e Discussão

Produced by Ltb. curvatus ST0403 bacteriocin was stable when exposed
to the investigated pHs, temperatures, chemicals. Based on performed biochemical and
physiological test, hemolytic, gelatinase, proteolytic and lipolytic activity, biogenic amines, and
antibiotic resistance, Ltb. curvatus ST0403 can be suggested as safe strain. Ltb. curvatus ST0403
did not demonstrate presence of virulence genes, including vanA,B,C,D,E,G. Bacteriocin ST0403
was expressed as 51200 AU/mL during stationary growth phase as recorded versus L.
monocytogenes L211. The addition of 6400 AU/mL bacteriocin produced by Ltb. curvatus
ST0403 (with adjusted pH to 6.0) to a 3-h-old culture of L. monocytogenes L211 (OD600nm 0.519)
resulted in growth inhibition for following monitored 12h, suggesting that the mode of activity of
studied bacteriocin is bactericidal.

Conclusão

Ltb. curvatus ST0403 is a bacteriocin producer with strong activity versus different
L. monocytogenes strains with potential in biopreservation. Ltb. curvatus ST0403 can be
considered safe and be applied for control of L. monocytoses in fermented dairy products.