Assessing the effect of organic residue quality on active decomposing fungi in a tropical Vertisol using 15N-DNA stable isotope probing

N-15-DNA stable isotope probing (N-15-DNA-SIP) combined with 18S rRNA gene-based community analysis was used to identify active fungi involved in decomposition of N-15-labeled maize and soybean litter in a tropical Vertisol. Phylogenetic analysis of N-15-labeled DNA subjected to 18S rRNA gene-based community fingerprinting showed that addition of maize residues promoted relatively slow-growing fungal decomposers (i.e. Penicillium spp., Aspergillus spp.), while addition of soybean residues promoted relatively fast-growing fungal decomposers (i.e. Fusarium spp., Mortierella spp.). Chaetomium spp. were dominant decomposers in both residue treatments. Therefore, we have clear evidence that specific members of the fungal community used N-15 derived from the two organic resources with contrasting biochemical quality for growth. Our study showed that N-15-DNA-SIP-based community analysis is a useful method to follow the fate of N from organic resources into the actively decomposing fungal community of soils. (C) 2010 Elsevier Ltd and The British Mycological Society. All rights reserved.