Characterization of soil microbial functional diversity in Pulau Tekak Besar, Tasik Kenyir

A.H. Nor Ayshah Alia, S. Tosiah, Z.Z. Norziana, Z. Abd. Jamil and M. Mohammad Radzali

Abstract

Pulau Tekak Besar is one of the 340 islands found in the biggest man-made lake in Southeast Asia, Tasik Kenyir. This study was conducted to evaluate the effect of land clearing on soil bacterial functional diversity of Pulau Tekak Besar. The study was conducted on 6 sampling areas, 3 disturbed (land clearing) and 3 non-disturbed soils, using the Biolog EcoPlate™ system which contained 31 useful carbon sources for soil bacterial functional diversity with characteristic reaction patterns known as metabolic fingerprints. Bacterial functional diversity was evaluated through microbial activity {colony forming unit (CFU) and average well-colour development (AWCD)} and community level physiological profile (richness and Shannon Weaver Index) using the metabolic fingerprint produced in 48 and 72 h. In general, AWCD values for undisturbed areas were higher compared to the disturbed areas. This indicated that soil microbial communities from these areas have higher metabolic diversity and carbon-mineralization compared to disturbed areas. The species richness for both areas was not significant which indicated that the microorganisms in the undisturbed and disturbed areas oxidized relatively similar number of carbon substrates. This showed that both areas had an equivalent number of different groups of microorganisms occuring together. The microbes in undisturbed areas utilized high carbon sources as compared to disturbed areas. Substrates such as D-galacturonic acid, D-mannitol, D-galactonic acid γ-lactone and N-acetyl-Dglucosamine were highly metabolized from both areas. It can be concluded that land clearing (disturbed areas) may influence microbial metabolic diversity and carbon-mineralization. However, microbial function from both areas did not change significantly.

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