Diversity of Actinomycetes in Tomato Plants

Abstract

Background: Tomato plant holds great biodiversity of actinomycetes. This diversity can be explored for new potential actinomycetes strains. Methods: Two different methods were followed for actinomycetes isolation (Serial dilution and direct streaking method). The direct streaking method was found to be the best method where it gave a higher number of actinomycetes compared to the plant extract method. All the actinomycetes were isolated by ISP2 medium supplemented with nystatin and cycloheximide (at 50 μg/ml). All the endophytic actinomycetes strains were isolated and purified based on the difference in appearances such as colony morphology, growth pattern, aerial hyphae growth, filamentous appearance and pigment production. Result: The direct streak method, yielded 192 isolates and only 48 isolates by plant extract method. Thus, a total of 240 strains were isolated. Plants from Madurai yielded a maximum of 130 isolates (54%) and a minimum from Tuticorin 20 isolates (8%). The highest viable count of 80.01±14.24 (CFU g-1) x 103 were recorded in the agro-fields of Dindugal followed by Madurai, Theni, Tirunelveli and Tuticorin. Out of 240 strains, 49.5% exhibited different aerial hyphae and 36.25% showed different filamentous appearances of growth and 5.8% produced pigments. The endophytic actinomycetes species isolated from tomato plants in different locations possess significant morphologically varied actinobacterial diversity. We can explore further on how these diverse actinomycetes are involved in plant growth promotion and protection against pathogens.