Microbial diversity in the termite gut: a complementary approach combining culture and culture independent techniques

Abstract:
The Formosan subterranean termite, Coptotermes formosanus Shiraki, is a highly destructive invasive pest species in many tropical and subtropical regions. The survival of this termite is dependent on its gut microbes (protozoa and bacteria). Therefore, alternative strategies may be devised in the future using the gut flora of termites as tools and targets for ecologically sound termite control. To facilitate development of such strategies, detailed knowledge of the microbial diversity in the termite gut is sorely needed. Also, it is important to know, which part of the gut flora can be cultured in order to test the physiological contributions of the bacteria to termite survival and to be able to manipulate them, e.g., by genetic engineering. In this study we used culture-independent 16S rDNA sequencing in conjunction with classical culture methods to describe the bacterial species composition in the gut of C. formosanus. The communal bacteria DNA from two termite colonies was extracted, cloned and sequenced. The 105 clones sequenced from both colonies resulted in 12 different bacteria strains from four different groups (Bacteroides, Treponema, Spirochaeta, Clostridiaceae). Bacteroides was the dominant group comprising over 80% of the gut flora in both colonies. The bacteria taxa identified in the gut of C. formosanus using culture-independent 16S rDNA sequencing were different from the bacteria we were able to culture from the gut of the same species. To date, we have cultured over 25 strains of bacteria, including species belonging to the Enterobacteriacea, Bacteroidales and Lactobacillales. All of the species identified by their 16S sequences and most of the cultured strains were novel species found exclusively in the termite gut. Bacteria culture and culture-independent techniques identified different parts of the termites’ gut community. Thus, it is recommended to use both methods in a complementary way to describe the microbial diversity and ecology in the termite gut.