Screening for Hydrolytic Enzymes Produced by Bacterial Species from Rhizospheric Soil in Akungba-Akoko

Abstract

Hydrolytic enzymes produced by bacteria have broad potential for substrate degradation and industrial processing. This study isolated, identified, and screened culturable bacteria from common bean (Phaseolus vulgaris L.) rhizospheric soil in Akungba-Akoko for amylase and protease production. Isolates were characterised using cultural, morphological, and biochemical tests, and their identities were determined by comparison with standard bacteriological descriptions. Amylolytic and proteolytic activities were screened on media containing 1% soluble starch or skim milk, respectively. Clear-zone formation indicated a positive reaction, and hydrolytic indices were calculated from the diameters of the clearance zones and colonies. Positive isolates were further evaluated by quantitative enzyme assays using the dinitrosalicylic acid method. Seventeen bacterial isolates representing nine genera were identified. Bacillus megaterium (D40) showed the highest amylolytic index (3.61) and amylase activity (5.45±0.14 U/mL). Pseudomonas sp. (B20) showed the highest proteolytic index (3.38) and protease activity (1.19±0.02 U/mL). Actinobacillus sp. (D42) had the lowest amylolytic index (0.08),  whereas Streptococcus sp. (C40) had the lowest proteolytic index (0.29). Several isolates showed no detectable activity for one or both enzymes. The findings demonstrate that bean rhizospheric soil contains culturable bacteria with variable amylolytic and proteolytic potential. These isolates may provide candidate sources for subsequent optimisation and characterisation of microbial enzymes intended for industrial applications.