Purpose: The purpose was to discern the genotypic/phenotypic structure of isolates from different spoiled finished food products. Information will be used to assess [a]distribution of genotypes, or existence of consistently occurring subtypes, and [b] patterns of occurrence or correlation to antimicrobial resistance or food processes.
Methods: Isolates (n = 82) were obtained from six different food types. DNA was isolated from each for 16S identification and RAPD subtyping. Sequence data was evaluated and patterns analyzed. Gas formation, dextran formation and nisin sensitivity were determined.
Results: Isolates were identified as either Weissella or Leuconostoc across 7 different species (L. mesenteroides, citreum, carnosum, pseudomesenteroides, W. confusa, paramesenteroides, cibaria) and segregated into subtypes (n = 35) distributed across food types. Five major RAPD subtypes composed 57% of observed diversity. Three major clades had members from across 3 major food types. The remaining clades represented < 2% of observed diversity. No correlation between tested phenotype and RAPD pattern was observed. Six isolates were tested, of which 4 were nisin sensitive and grouped in one major RAPD subtype; the remaining isolates (resistant to 100 ppm nisin) clustered in a minor clade.
Significance: Knowing predominant subtypes of Leuconostocaceae can focus antimicrobial research and intervention efforts on the more important spoilage organisms instead of less-significant or randomly occurring minor contaminants. This is perhaps the first investigation to ascertain the common Leuconostocaceae subtypes potentially impacting a large portion of food production and shelf life.