Evaluation of Holocellulase Production Capacity of Alcaligenes spp by Submerged Fermentation for Potential Valorization of Corn Cob

Cellulase and hemicellulase are key enzymes required for biological saccharification and valorization of lignocellulosic wastes. Hence, the search for microbes with ability to simultaneously produce both enzymes for cost-effective and ecofriendly bioprocessing of waste is crucial. In this study, the capacity of two holocellulolytic bacterial isolates to produce cellulase and hemicellulase using corn cob as sole carbon source was investigated under different cultivation conditions.

Screening for holocellulolytic bacteria was carried out in agar plates and by submerged cultivation in corn cob-based media at pH 7.0 and 180 rpm for 21 days. Enzyme yield during cultivation was monitored at 72 h intervals and identity of bacterial isolates was determined by 16S rRNA gene sequencing. Effects of process parameters such as substrate concentration, inoculum concentration, nitrogen source, pH and temperature on enzyme production were investigated to obtain optimum conditions for holocellulase production.

This study reveals two holocellulolytic bacterial strains belonging to the genus Alcaligenes. Cellulase and hemicellulase yield from Alcaligenes sp. CFF-02 (111.60 and 128.35 U/mg) and Alcaligenes faecalis CFF-06 (74.62 and 134.34 U/mg) during quantitative screening was maximum on 15 days. Optimum concurrent production of cellulase and hemicellulase from Alcaligenes spp was achieved using 1% (w/v) corn cob, 12% (v/v) inoculum, pH 5.0 at 30 °C (Alcaligenes sp. CFF-02) and 40 °C (A. faecalis CFF-06), respectively.

Findings show that both species of Alcaligenes are viable bioresources with capacity to utilize corn cob for production of high yield of holocellulase required for biomass saccharification in biorefineries.