Phenotypic characterization and ecological succession of microorganisms during the fermentation of Cassava and Maize

Abstract

Fermented foods are consumed by a very large population in Africa but the products have many drawbacks ranging from shelf life instability to contamination and toxicity. These foods therefore require an upgrade through improved fermentation processes. This work determined the phenotypic characteristics of the fermenting microorganisms and microbial ecological succession during fermentation of cassava and maize to determine the predominant fermenting microorganisms. Cassava roots and maize grains were fermented using the traditional method of processing them into fufu and ogi for 72 h and 48 h respectively. Samples were drawn every 12 h for analysis. Enumeration and characterization of lactic acid bacteria were carried out on MRS medium with subsequent microscopic examination, physiological, biochemical reaction tests and API 50 CH gallery. Yeast isolates were identified by their morphological characteristics. Thirteen lactic acid bacteria were isolated from the fermenting cassava and 6 from the fermenting maize. The Isolates were Gram positive and catalase negative. Lactobacillus plantarum, L. fermentum and L. pentusus predominated in both fermentations while Candida tropicalis, C. krusei and Saccharomyces cerevisae also predominated in both fermentations. Candida inconspicuo was found only in cassava fermentation. The results of this work revealed the microbial ecology of fermented cassava and maize which is a prerequisite to the understanding needed to develop a multifunctional starter culture for these fermentations for their upgrade. Keywords: Cassava, Maize, Fermentation, lactic acid bacteria, Yeasts.