Classification of a bacterial isolate, from pozol, exhibiting antimicrobial activity against several gram-positive and gram-negative bacteria, yeasts, and molds

A bacterial isolate, designated CS93, capable of producing a broad-spectrum antimicrobial compound(s) effective against gram-positive and gram-negativ e bacteria, yeasts, and molds was isolated from pozol, a fermented maize pr oduct. This strain was phenotypically similar to another pozol isolate that was previously designated as Agrobacterium azotophilium by other investiga tors. By using biochemical, phenotypic, and 16S rRNA sequence analysis, bot h pozol isolates were identified as members of the genus Bacillus, possibly a variant of Bacillus subtilis. While the antimicrobial compound(s) was in itially produced only on a solid medium, parameters were identified for pro duction in broth. The compound(s) was heat stable (121 degrees C for 15 min ), exhibited activity over a wide pH range (pH 3 to pH 11), and was inactiv ated by pronase E. The antimicrobial compound(s) was bactericidal and bacte riolytic against Escherichia coli V517, bacteriostatic against Micrococcus luteus, and fungistatic against Saccharomyces cerevisiae. The inhibitory co mpound(s) could possibly serve as a food biopreservative.