Isolation and molecular characterization of cellulase producing bacteria from rice mill wastewater in Hadejia, Jigawa State, Nigeria

Abstract

Cellulose, the most abundant renewable biopolymer on Earth, constitutes a major component of lignocellulosic agricultural residues and serves as a key substrate for sustainable bioresource utilization. Efficient bioconversion of cellulose into fermentable sugars largely depends on cellulolytic microorganisms capable of producing robust cellulase enzymes. This study aimed to identify and characterize cellulase-producing bacteria from rice mill wastewater in Hadejia, Jigawa State, Nigeria—an underexplored ecological niche for cellulolytic microbes. Wastewater samples were collected from ten rice milling sites and analyzed for selected physicochemical parameters. Bacteria were recovered via serial dilution and cultured on carboxymethyl cellulose (CMC) agar for primary screening. A total of 36 isolates were obtained, and the most active strains were selected based on cellulolytic activity assessed using Gram’s iodine flooding method and hydrolysis capacity (HC) indices. Molecular identification was performed through 16S rRNA gene sequencing and phylogenetic analysis. The wastewater exhibited temperatures of 31–35 °C and slightly acidic to neutral pH (6.3–6.9). Two isolates showed strong cellulolytic activity with high HC values, and sequence analysis revealed close similarity to Proteus mirabilis and Dechloromonas spp. These findings highlight rice mill wastewater as a promising source of cellulase-producing bacteria with potential applications in lignocellulosic biomass conversion and industrial biotechnology.