Molecular Characterization and Potential of Fungal Species Associated with Cassava Waste

Abstract

Aims: Efficient utilization of cassava waste for value addition depends largely on proper understanding of its true microbial diversity. The aim of this study was to characterize using molecular methods, fungal species associated with cassava waste and to highlight their industrial potential.  Study Design: Cassava peel (CP) waste from CP waste dumpsites and cassava waste water from cassava wastewater discharge outlets were collected from major cassava processing centres in Abeokuta, Ogun State, Nigeria, for the study. Place and Duration of Study: Biotechnology Centre, Federal University of Agriculture, Abeokuta, Ogun State, Nigeria; between June 2011 and March 2012. Methodology: Two molecular methods namely, total fungal community DNA and isolates DNA sequence analysis were employed to characterize and identify the fungal species. Total fungal community DNA was extracted directly from CP waste and cassava wastewater, using the Soil DNA isolation kit (Norgen, Canada), while total genomic DNA was extracted from fungal isolates, using the same kit. The fungal ITS2 (Internal transcribed spacer) gene sequence of total fungal community and genomic DNA was amplified by Polymerase Chain Reaction (PCR) using ITS2 primers. Total fungal community DNA amplicons were spliced into PCR-TRAP Cloning Vector, used to transform competent cells of Escherichia coli and sequenced. Sequences were identified by aligning with sequences in the GenBank. Results: Results showed that 17 fungal species including Eurotiomycetes – Eurotiales (6 species), Mucormycotina – Mucorales (1 species), Sordariomycetes - Hypocreales (1 species), Saccharomycetes Saccharomycetales (8 species), and unidentified fungi (1 species) were present in cassava peel (CP). The dominant species was Aspergillus niger (15.2%). However, cassava wastewater had 27 fungal species including Eurotiomycetes – Eurotiales (2 species), Saccharomycetes Saccharomycetales (24 species) Tremellomycetes-Tremellales (1 species); the dominant species being Saccharomyces cerevisiae and Candida krusei each with 8.7% relative abundance. Conclusion: This study shows that cassava waste, on account of its rich fungal diversity, is an important microbial resource.