13. Evaluation of endophytic fungi extract for their antimicrobial activity from Sesbania grandiflora (L.) Pers.

A total of 69 endophytic fungi were isolated from Sesbania grandiflora (L.) Pers. Their antimicrobial activities were already primary screened by agar diffusion assay and antagonistic activities. The ethyl acetate crude extracts of 28 selected endophytic fungi were further determined for Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) or Minimum Fungicidal Concentration (MFC) against bacteria (Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 278530), yeast (Candida albicans and Cryptococcus neoformans) and mold (Rhizopus spp., Mucor spp., Aspergillus spp., Alternaria spp., Curvularia spp., and Penicillium spp.) by using the standard broth microdilution method and a modified resazurin microtiter plate assay. It was found that 26 in 28 extracts exhibited high anti bacterial activity against B. subtilis with the susceptibility rate at 92.86% than P.aeruginosa (82.14%), S.aureus (42.86%), and E.coli (7.14%) respectively. The MIC and MBC of this group were in the range of 0.49-250μg/mL and 1.95≥250μg/mL, respectively. Seventeen extracts (60.71%) showed antifungal activity against C.neoformans than C.albicans (42.86%) with the MIC and MFC were in the range of 31.25-250μg/mL and 250μg/mL, respectively, whereas 23 extracts (82.14%) showed high antifungal activity against Mucor spp. than Rhizopus spp. (75%), Alternaria spp. (60.71%), Curvularia spp.(57.14%), Penicillium spp. (53.57%) and Aspergillus spp. (3.57%) respectively, with MIC and MFC in the range of 62.50-250μg/mL and 250μg/mL respectively. Study of macroscopic and microscopic examination of fungal morphology revealed that most of endophytic fungi are hyaline septate hyphae but 3 isolates are hyaline non-septate hyphae. Fusarium spp. and Acremonium spp. are the predominate species among selected endophytic fungi. These results of this study strongly suggested that metabolites of endophytic fungi from Sesbania grandiflora (L.) Pers. could be a good potential source of bioactive natural products against some bacteria yeast, and molds.