Antimicrobial Activities of Actinomycetes Isolated From Flooded and Unflooded Soils

Abstract

Introduction: Flooding may cause the microbial population in the soil to move from one area to another. Actinomycete, a type of soil microbe, has the most commercial value due to its ability to produce secondary metabolites. This study aimed to elucidate the antimicrobial activities of actinomycetes isolated from flooded and unflooded areas. Methods: Soils samples were collected from flooded areas in Dabong, Kelantan, and unflooded areas in Jeli, Kelantan. Three isolation methods were used to isolate actinomycetes; Sonication, Centrifugation and Chloramine T. The isolated strains were screened for morphological characteristics based on their growth pattern (spore formation), colony color, aerial and substrate mycelia color, and soluble pigment formation in the growth medium. Morphologically different strains were tested against Escherichia coli and Candida albicans for its antibacterial and antifungal activities. Results: A total of 970 actinomycete strains were isolated from soil samples (570 strains from flooded soil and 400 strains from unflooded soils). Only 281 strains were morphologically different. Thirty actinomycete strains were tested for antibacterial and antifungal activity. Seventeen of these inhibit at least one test microorganism. Conclusion: In conclusion, our observations reveal that the soil samples obtained from flooded areas display a wide variety of actinomycetes, as evident from their morphological characteristics. This finding suggests that the flooded soil areas possess a higher diversity of actinomycetes compared to non-flooded soil areas. Furthermore, we found that 57% of the tested actinomycete strains exhibited activity against at least one test organism, indicating their potential for future research.