Lactic acid bacterial diversity in the traditional Mexican fermented dough pozol as determined by 16S rDNA sequence analysis

The lactic acid bacteria diversity of pozol, a Mexican fermented maize dough, was studied using a total DNA extraction and purification procedure and PCR amplification of 16S rDNA for Gram-positive and related bacterial groups. Thirty-six clones were obtained and sequenced to 650 nucleotides. These partial sequences were identified by submission to the non-redundant nucleotide database of NCBI. The identified sequences were aligned with reference sequences of the closest related organisms. This analysis indicated that only 14 sequences were unique clones and these were identified as Lactococcus lactis, Streptococcus suis, Lactobacillus plantarum, Lact. casei, Lact. alimentarium, and Lact. delbruekii and Clostridium sp. Two non-ribosomal sequences were also detected. Unlike other environments analyzed with this molecular approach where many unidentified microorganisms are found, the identity of most sequences could be established as lactic acid bacteria, indicating that this is the main group among the Gram-positive bacteria in pozol. Use of this molecular method permitted detection of lactic acid bacteria different from those previously isolated and identified by culture techniques