Molecular Identification of Amylase-Producing Bacteria Isolated from Cassava Soil Sample at Abuja, Northern Nigeria

Background: Amylases, which are essential enzymes responsible for the breakdown of starch into glucose, serve pivotal functions across various industrial sectors, such as the food and pharmaceutical industries. This study focused on identifying amylase-producing bacteria from a soil sample collected at a cassava production site. Methods: Soil samples were subjected to serial dilution and cultured on starch agar plates to isolate potential amylase-producing bacteria. Nutrient agar was used as the basal medium, and plates were incubated at 37°C for optimal bacterial growth. Isolates demonstrating amylase activity were identified by the formation of clear zones around the colonies upon exposure to a 1% iodine solution, indicating starch hydrolysis. Enzymatic activity was further quantified using the dinitrosalicylic acid (DNSA) reagent method to assess reducing sugar release. For molecular identification, genomic DNA was extracted from the two isolates exhibiting the highest enzyme activity. The 16S rRNA gene was amplified via polymerase chain reaction (PCR) using universal bacterial primers 27F and 1492R. PCR products were sequenced, and the resulting nucleotide sequences were analyzed using BLAST for species-level identification. Results: A total of five bacterial isolates, designated B1 through B5, demonstrated amylase-producing potential as evidenced by clear zone formation on starch agar. Among them, isolates B1 and B3 exhibited the highest levels of enzymatic activity as determined by the DNSA assay. Subsequent molecular identification based on 16S rRNA gene sequencing revealed that isolate B1 shared 99.41% sequence similarity with Bacillus cereus, while isolate B3 exhibited 99.88% similarity to Staphylococcus saprophyticus. These findings confirm the identity of two high-performing amylase-producing strains isolated from the soil sample. Conclusion: The results of this study provide insight into potential sources of amylase which could be exploited for industrial purposes.