Full Length Research Paper

PCR-DGGE fingerprints of microbial successional changes during fermentation of cereal-legume weaning foods

Wakil S. M.¹*, Onilude, A. A.¹, Adetutu E. M.² and Ball A. S.²

¹Department of Botany and Microbiology, University of Ibadan, Ibadan, Nigeria.

²Flinders University, School of Biological Sciences, Adelaide, Australia.

*Corresponding author. E-mail: shemowak@yahoo.com. Tel: 2348034129496.

Accepted 30 October, 2008

Phenotypic identification and monitoring of the dynamics of naturally occurring microbial community responsible for the spontaneous fermentation of different cereal-legume weaning blends was carried out. Enumeration using culture-dependent method showed that cell counts increased within the first 24 h with the highest total viable count of 1.2 x 10¹² cfu g^-1 in maize-legume (1A) blend. Yeast counts increased drastically and no enterobacteria were observed within the first 24 h. At all fermentation times, acidity increased within 48 h and lowest pH value (3.60) was reached in maize–based blend.  Phenotypic identification revealed that the isolated bacteria belong to the genera Bacillus species, Staphylococcus aureus, and Escherichia coli. The yeast isolates were identified as Saccharomyces cerevisiae, Saccharomyces species and Hansenula species while Lactobacillus plantarum and Pediococcus acidilactici were the predominant lactic acid bacteria (LAB). The analysis of the denaturing gradient gel electrophoresis (DGGE) pattern obtained with bacterial and LAB primers targeting the V3 region of the 16S rDNA genes clearly demonstrated that there was a major shift in the community structure within the first 24 h.

Key words: Successional changes, microbial communities, fermented weaning foods, PCR-DGGE.