Molecular Characterization and Potential of Bacterial Species Associated with Cassava Waste

Abstract

Knowledge of the true microbial diversity in cassava waste (CW) is fundamental to effective utilization of this waste. This paper reports, on the identification of bacteria species associated with CW, using molecular tools. The 16S rRNA gene of total bacteria community and bacterial isolates were amplified by Polymerase Chain Reaction (PCR) using 16S rRNA primers. Total microbial community DNA amplicons were spliced into the PCR-TRAP Cloning Vector, used to transform competent cells of Escherichia coli and sequenced. Sequences were identified by aligning with sequences in the GenBank. Twenty four bacterial species were detected in cassava peel (CP) belonging to Bacillus-Bacillales (7 species), Bacillus-Lactobacillales (12 species), Gamma- proteobacteria (3 species), Acinetobacteria-Actinomycetales (1 species) and uncultured bacteria (2 species). Bacillus licheniformis (11.3%) and B. substilis (11.3%) were the dominant species. Azotobacter vinelandii, an uncultured bacterium clone  ncd1462c07c1 and an uncultured compost bacteria clone PS2630 identified in this study, probably has not been reported in cassava fermentation. In cassava wastewater (CWW), 26 bacterial species were detected including Bacillus-Bacillales (5 species), Bacillus-Lactobacillales (18 species), Gammaproteobacteria (2 species), Acinetobacteria-Actinomycetales (1 species),  Beta-proteobacteria (1 species) and uncultured bacteria (1 species). Lactobacillus fermentum (11.1%) was the dominant species closely, followed by L. plantarum (10.7%). The potential of some of the species are highlighted. This study has shown that CW is an important microbial resource, considering its rich bacterial diversity.

Keywords: Cassava waste, molecular characterization, community DNA, 16S rRNA, cloning.