Production and characterization of plantaricin Y11 from Lactiplantibacillus Plantarum strain y11 (MW642245.1) isolated from Nigerian food samples and their applications in preserving milk

Bacteriocin from lactic acid bacterium (LAB) was characterized and its biopreservation assay carried out using conventional  methods and integrative approaches. About 66.7% (n=180) of the bacterial strains isolated from twelve different  fermented/non-fermented food products were potential LAB strains by biochemical characterization. The  highest bacteriocin  producing strain was selected and confirmed with 16S rRNA sequencing and submitted to GenBank  of National Center for  Biotechnology Information as Lactiplantibacillus plantarum strain Y11 (Accession number:  MW642245.1). Polymerase  Chain Reaction (PCR) revealed the presence of virulence genes (cytotoxin K and haemolysin  C) in L. plantarum Y11. The  bacteriocin produced was labelled as plantaricin Y11 with molecular weight of 1540 Da,  amino acid sequence was  NSHGTADYCVMWLIXK, and possessed the merits of wide pH stability (2–10), high thermal  stability and sensitivity to  protease. The bacteriocin showed wide spectrum of activity against bacterial reference strains  with bacteriocin activity  ranging from 3200Au/mL to 6400Au/mL. Preservative potentials of the bacteriocin  compared favourably with sodium benzoate in milk, inhibiting bacterial and fungal load compared to the control. There  was log reduction of aerobic mesophilic bacterial count of 8.02±0.15 and 8.43±0.21 Log 10 CFU/mL in milk treated with  plantaricin Y11 and sodium benzoate,  respectively. The log reductions of fungal count in plantaricin Y11 and sodium  benzoate treated milk ≥4.41±0.11 and  ≥3.1±0.2 Log 10 CFU/mL respectively. The plantaricin Y11 was then classified as  class IIa in bacteriocin classification  schemes and it sustained some organoleptic conditions of milk making it a  promising candidate for safe bio-preservatives.