Antimicrobial agents from endophytic fungi Aspergillus terreus isolated from Zingiber cassumunar Roxb. rhizomes

Abstract

The purpose of this research was to isolate antimicrobial compounds from endophytic fungi isolated from Zingiber cassumunar rhizomes obtained from Surin, Supanburee, Songkhla and Pathumthanee province. The endophytic fungi were isolated using surface-sterilization technique to give 48 isolates including 59% Mycelia sterilia, 35% Fusarium sp., 4% Aspergillus sp. And 2% Schlerotium sp. All isolates were examined antimicrobial activity using agar plate bioassay. The results showed that 10 isolates of the fungi inhibited tested microorganisms. Isolate ZcSR5-4 was selected for the study because it exhibited activity against Bacillus subtilis and Escherichia coli with inhibition clear zone 1.50 and 2.50 cm, respectively while others showed less activity. Based on morphology and nucleotide sequencing of Internal Transcribed Spacer (ITS) regions of rDNA, isolate ZcSR5-4 was identified as Aspergillus terreus. Mycelium and broth of isolate ZcSR5-4 were isolated by extraction and chromatographic technique to give 3 known compounds. On the basis of physical properties and spectroscopic data, they were elucidated as butyrolactone I, butyrolactone III and butyrolactone IV. These compounds were examined Inhibitory Concentrations (MICs). Butyolactone I inhibited B. subtilis ATCC6633, S. aureus ATCC25923, E. coli ATCC25922 with the MICs values of 62.5 [microgram]/ml. (147.41 [micrometre]) and C. albicans ATCC10231 with the MICs values of 15.63 [microgram]/ml (36.86 [micrometre]; butyrolactone III inhibited all tested microorganisms and butyrolactone IV inhibited B. subtilis ATCC6633, S. aureus ATCC25923, E. coli ATCC25922 and P. aeruginosa ATCC27853 with the MICs values of 7.82 (17.77 [micrometre]), 31.25 (71.02 [micrometre]), 62.50 (142.04 micrometre) and 62.50 [microgram]/ml (142.04 micrometre]), respectively. In addition, all compounds were inactivity on cytotoxicity against 5 tumor cell lines.