ABSTRACT

This research project aimed to isolate and characterize amylase-producing lactic acid -bacteria—(LAB) from starchy foods,~specifically ogi and fufu, and evaluate their antimicrobial activities. A total of fourteen lactic acid bacteria isolates were obtained and identified based on morphological, biochemical, and physiological characteristics. Ten of these isolates demonstrated amylase production, with three strains, Lactiplantibacillus plantarum FM02, Lactiplantibacillus plantarum Z2, and Lactiplantibacillus pentosus BRS3, exhibiting high amylase activity. These strains were further identified using 16S ■ rRNA sequencing and characterized for their amylase production, antimicrobial activity, and probiotic properties. The amylase activity ofthe three strains was evaluated using both qualitative and quantitative methods, with Lactiplantibacillus plantarum FM02 showing the highest activity of 0.85±0.05 U/mL. The optimal culture conditions for amylase production were determined, with cassava flour and peptone identified as the most efficient carbon and nitrogen sources, respectively. The amylase enzyme from Lactiplantibacillus plantarum FM02 was purified 2.63-fold with a specific activity of 0.10 U/mg and exhibited thermal stability at temperatures up to 60°C.The antimicrobial activity of the lactic acid bacteria isolates was evaluated against Escherichia coli, Enterobacter aerogenes, and Staphylococcus aureus using agar well diffusion techniques. The results showed significant zones of inhibition, ranging from 9.83mm to 13.04mm, indicating the potential of these strains as antimicrobial agents. Additionally, the probiotic properties of the isolates, including acid and bile tolerance, autoaggregation, coaggregation, and cell hydrophobicity, were evaluated, and the results suggest that these strains have potential as probiotics.The ' safety assessment of the strains revealed no hemolytic activity, gelatinase, or DNase production, indicating their non-pathogenic nature. The thermostability and probiotic properties of these amylolytic LAB make them suitable for applications in food, brewing, and other industries, and as starter cultures for food fermentations. The use of cheaper agroindustrial substrates like cassava flour and peptone as nutrient additives may enhance amylase production and provide a cost-effective solution for industrial applications. Overall, this study highlights the potential of amylolytic LAB isolated from starchy foods as antimicrobial agents, probiotics, and starter cultures for food fermentations. The findings of this research have significant implications for the development of novel food preservation strategies and the production of value-added products in various industries.