Phylogenetic analysis of the symbiotic intestinal microflora of the termiteCryptotermes domesticus

Abstract

The phylogeny of microorganisms of the symbiotic community in the gut of a lower termite, Cryptotermes domesticus (order Isoptera, family Kalotermitidae), was investigated without culturing the resident microorganisms. Portions of the small-subunit rRNA genes (16S rRNAs) were directly amplified from the mixed-population DNA of the termite gut by the PCR and were clonally isolated. Analysis of partial sequences of 16S rRNA showed the existence of prokaryotic species related to the genera Methanobrevibacter, Leuconostoc, Bacteroides and Treponema, but most of the sequences were those of yet unknown species. Unique sequences showing very low sequence similarity to known 16S rRNA sequences were also found although they were significantly clustered with the High G+C Gram-positive bacteria. Comparisons of these sequences with those from the symbiotic microorganisms in other termite species revealed the existence of termite-specific groups of organisms.