SECONDARY METABOLITES OF ASPERGILLUS SP ISOLATED FROM LAKE ELEMENTAITA

Abstract

The soda lakes of Kenya provide an extreme environment where diverse groups of microorganisms thrive. Soda lakes are characterized by great variation in temperature, halophillic and alkaliphilic- extreme conditions. Fungi from such extreme environment may have modified their biosynthetic pathways to produce enzymes and compounds with antimicrobial activity. A fungus in the genus Aspergillus was isolated from the sediments of Lake Elementaita and screened for the ability to produce secondary metabolites. The objective of this study was to characterize and identify the fungus and screen for potential production of secondary metabolites. Malt extract agar was used for the isolation of fungus from the sediments, morphological studies as well as the effect of temperature, salinity and pH on growth. Molecular characterization of the 18s rDNA was done using fungal primers in this study. Fermentation of fungal isolate in 500ml conical flasks was done in fourteen days duration under a shaker. Extraction of the filtrate was done using the solvents, Ethyl acetate and hexane in the ratio 4:1. A rotary evaporator was use to evaporate the filtrate. The dry pellet was eluted in 1ml ethyl acetate, Antimicrobial activity was assayed using six millimeter paper disc loaded with the elute. GC-MS was used to analyze and identify the secondary metabolites produced by the fungus. The fungus grew well in alkaline pH and a temperature range of 26º C to 30 ºC. Growth was only observed on 0% to 10% NaCl.M olecular analysis showed that the isolate is closely aligned to the genus Aspergillus GC-MS identified a range of groups of metabolites from the isolates and some are kwon to have antimicrobial activity. The results shows that this fungus can only tolerate relatively low NaCl concentration of up to 10% .and grows best at alkaline conditions. The fungus has potential for producing metabolite which can be explored for future application in industries and pharmaceuticals.