Abstract:
The mutualistic association between termites and their gut symbionts has continued to attract the curiosity of
researchers over time. The aim of this study was to characterize group-specific bacterial community structure and
diversity in the gut of three fungus cultivating termites Macrotermes michaelseni, Odontotermes and Microtermes
species using PCR-denaturing gradient gel electrophoresis (PCR-DGGE) analysis. Group-specific primers targeting
members of the phyla Bacteroidetes, Firmicutes and Planctomycetes were used for PCR amplification of total DNA
mixture extracted from termite guts. The PCR products were used as templates in a second PCR with nested
bacteria DGGE-PCR primer pairs whose products were separated by DGGE. Representative DNA bands were
excised from the gels, re-amplified, purified and sequenced. The sequences were blast analyzed and together with
other reference sequences retrieved from the public GenBank were used to infer phylogenetic trees. All sets of
sequences were deposited in the public GenBank. Results from the DGGE band patterns revealed a sharp contrast
between the bacterial communities of M. michaelseni, Odontotermes and Microtermes species. This underlines the
difference in group-specific bacterial diversity in the three termites. Phylogenetic analysis of the 16S rRNA gene
sequences indicated that they were affiliated with the three phyla: Bacteroidetes, Firmicutes and Planctomycetes.
Sequences (40%) affiliated with the phylum Planctomycetes were isolated and clustered with ‘Termite
planctomycete cluster’, indicating that they are termite gut specific members. Sequences (89%) isolated were
often affiliated with sequences obtained from other termites’ guts, demonstrating that a majority of the gut
bacteria are autochthonous having mutualistic relationship with their hosts. Notably, the isolated sequences had
less than 96% sequence similarity with the closest cultivated strains, indicating that the majority of termite gut
bacterial lineages are still uncultured. The results will help better understand the bacterial symbionts-termites
mutualistic associations.
