Carbon ecology of termite gut and phenol degradation by a bacterium isolated from the gut of termite.

Metagenomics and transcriptomics have had some success analyzing community and functional ecology of the termite gut, but carbon utilization ecology and the effect of diet on the gut community are not well understood. This study was done to determine the effect of three hardwood tree types, oak (Quercus spp.), red maple (Acer rubrum), and tupelo (Nyssa aquatica) on the termite species, Reticulitermes flavipes in the family Rhinotermitidae. Termite abdomen homogenates were incubated on agar plates containing three common carbon sources in the termite gut, namely, acetate, cellobiose, and phenol under aerobic and anaerobic conditions. Bacterial growth was higher on cellobiose than any other carbon source. Higher bacterial growth on cellobiose was observed from termite colonies feeding on oak than on phenol from the other two wood types. The difference between aerobic and anaerobic conditions was not significant. A bacterium, Acinetobacter tandoii isolated and identified from our previous study was subjected to high concentrations of phenol as the sole carbon source and this bacterium was able to degrade phenol concentration up to 600 mg/L.

Biodegradation of phenol by Acinetobacter tandoii isolated from the gut of the termite.

The diet of wood-feeding termites (WFT) consists of cellulose, hemicellulose, and lignin. Cellulose and hemicellulose are utilized by symbiotic protozoa as a carbon source. Protozoa produce acetate, which is the carbon source of the termite. Recently, the mechanisms by which lignin is modified by termites have been reported. Lignin is broken down into its phenylpropanoid monomers and phenolic compounds. Bacteria from WFT gut capable of degrading lignin metabolic products are potentially valuable for bioremediation and biofuel production. A bacterium was isolated from the gut of the WFT and identified as Acinetobacter tandoii. This bacterium was capable of utilizing phenol as the sole carbon source and was able to completely degrade phenol at the concentration of 280 mg/L. A. tandoii degraded phenol via the ortho and ß-ketoadipase pathway. This bacterium is a known phenol degrader, but to our knowledge, this is the first time it was isolated and tested for phenol-degrading ability from termites.