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. Sodalakes are characterized by great variation in temperature, halophillic and alkaliphilic- extreme conditions. Fungifrom such extreme environment may have modified their biosynthetic pathways to produce enzymes andcompounds with antimicrobial activity. A fungus in the genus Aspergillus was isolated from the sediments of LakeElementaita and screened for the ability to produce secondary metabolites. The objective of this study was tocharacterize and identify the fungus and screen for potential production of secondary metabolites. Malt extractagar was used for the isolation of fungus from the sediments, morphological studies as well as the effect oftemperature, salinity and pH on growth. Molecular characterization of the 18s rDNA was done using fungal primersin this study. Fermentation of fungal isolate in 500ml conical flasks was done in fourteen days duration under ashaker. Extraction of the filtrate was done using the solvents, Ethyl acetate and hexane in the ratio 4:1. A rotaryevaporator was use to evaporate the filtrate. The dry pellet was eluted in 1ml ethyl acetate, Antimicrobial activitywas assayed using six millimeter paper disc loaded with the elute. GC-MS was used to analyze and identify thesecondary metabolites produced by the fungus. The fungus grew well in alkaline pH and a temperature range of26º C to 30 ºC. Growth was only observed on 0% to 10% NaCl.M olecular analysis showed that the isolate is closelyaligned to the genus Aspergillus GC-MS identified a range of groups of metabolites from the isolates and some arekwon to have antimicrobial activity. The results shows that this fungus can only tolerate relatively low NaClconcentration of up to 10% .and grows best at alkaline conditions. The fungus has potential for producingmetabolite which can be explored for future application in industries and pharmaceuticals.