Antimicrobial properties and detection of crude extract derived from Magnolia garrettii inhabiting fungi

Abstract

One hundred and fifty three isolates of endophytic and saprobic fungi were isolated from healthy-living and decayed-fallen branches of Montha Pa (Magnolia garrettii (Craib) V.S. Kumar) in order to examine their antimicrobial potentials. Each fungal isolate was grown in five different culture media (F1, F3, F4, F5 and PDB) and incubated at room temperature for 6 days with shaking (130 rpm). Antimicrobial activity of each isolate was determined using paper disc diffusion assay of culture filtrate against Bacillus cereus, Candida albicans, Escherichia coli, Staphylococcus aureus and Pectobacterium carotovorum. The results showed that 19 culture filtrates exhibited an inhibitory activity towards at least one of the pathogens although none was found to suppress P. carotovorum. Further analysis of culture filtrate crude extract and mycelial crude extract from isolate MG5/2.4-1 and Chaetomium sp. 1MG9001 using thin layer chromatography showed the culture filtrate crude extract contained flavonoids, steroids, terpenoids, aldehydes, ketones, unsaturated compounds and alcohols, while the mycelial crude extracts was made largely of terpenoids, unsaturated compounds and alcohols. Evaluation of the two extracts against B. cereus, E. coli and S. aureus showed higher antimicrobial efficiency of the culture filtrates than that of the mycelial extracts and even greater than chloramphenicol in the case of S. aureus. Further studies on purification and characterization of the compounds in all crude extract are ongoing. Results from morphological and molecular studies suggested that Chaetomium sp. 1MG9001 is Chaetomium bostrychodes and the fungal isolate MG5/2.4-1 is the species belongs to the genus Diaporthe.