GROUP-SPECIFIC BACTERIAL DIVERSITY IN THE GUT OF FUNGUS-CULTIVATING TERMITES (MACROTERMES, ODONTOTERMES AND MICROTERMES SPECIES) FROM KENYA

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.

Key words: Bacterial diversity, termites, PCR-DGGE