Journal of Applied Biosciences (J. Appl. Biosci.) [ISSN 1997 - 5902]
Volume 26: 1604 -1613. Published February 8, 2010.
Monitoring the effect of fortification on bacterial population dynamics in malted and fermented maize-based weaning foods using PCR-DGGE
Wakil Sherifah Monilola* and Onilude Abiodun Anthony
Department of Botany and Microbiology, University of Ibadan, Ibadan, Nigeria.
*Corresponding author email:Shemowak@yahoo.comABSTRACT
Objective: To evaluate the effect of fortification on the microbial population dynamics of naturally fermenting maize– legume weaning blends.
Methodology and results: Maize fortified with cowpea, and cowpea-groundnut blends were formulated and spontaneously fermented for 72h. Enumeration using culture- dependent method revealed that microbial cell counts increased drastically within the first 24h in maize-cowpea blends while it took longer (within the first 48h) in maize-cowpea-groundnut blends. The analysis of the Denaturing Gradient Gel Electrophoresis (DGGE) pattern of the fermented blends obtained with bacterial primers targeting the 16S rDNA genes clearly demonstrated that there was a major shift in the community structure within the first 24h. The species richness (R) for the total bacterial community varied from a low value (9) for maize-cowpea blends to a 15 for maize-cowpea -groundnut blends. The biodiversity index (H’) as well as concentration of dominance (S) according to Shannon and Weaver and Simpson’s index, respectively, varied significantly with the supplementation type with the maize-cowpea -groundnut sample maintaining high biodiversity throughout the fermentation period. Statistical analysis showed a significant difference (P<0.05) in the total bacterial diversity within samples with increase in fermentation time as well as between the two formulations.
Conclusion and application of findings: Conclusively, the study showed that the shift in microbial dynamics is determined more by the supplement used and to a lesser extent by the length of fermentation period. Based on the results obtained in this work, it is recommended that fortification of maize gruel with cowpea –groundnut mixture will be preferred in order to enhance fermentation of the blend within a very short time.
Key words: Bacterial communities fermented weaning food, species richness, PCR-DGGE.
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