A study on effects of some inorganic compounds and plant essential oils on cellulolytic activity of endosymbionts in their digestive system on Amitermes vilis (Isoptera: termitidae).

Termites are considered as one of the most important and largest groups of insects in terrestrial ecosystems that decompose lignocelluloses. Isolation and characterization of cellulolytic strains from termites will also provide information for understanding the efficient mechanism of lignin degradation in termites. In the present study, some termite specimens were collected from traps in Khojir Protected Area in Jajrud district of Pardis County, Tehran Province, Iran, and all were identified as Amitermes vilis. Five bacterial isolates in charge of decomposing celluloses were extracted from termite’s gut. The isolates ASB1, ASB2, ASB3 and ASB5 were identified as Bacillus cereus, B. circulans, B. circulans and B. licheniformes, respectively. A Gram-negative bacterium encoded ASB4 was also characterized but not precisely identified. In order to determine the amount of cellulolytic activities of the strains ASB1 and ASB4, both were grown on Cellulose Congo red agar medium. The clear zones around the mass colonies were measured 5 and 4 mm, respectively. Subsequently, the amount of absorbed glucose was measured by spectrophotometery. The effects of garlic, caraway and basil essential oils along with two mineral compounds, boric acid and tungsten were examined against cellulolytic activities of the five bacterial isolates by congo red assay. All tests were performed with three different concentrations of 10, 50 and 100 ppm in three replicates. The results showed a significant reduction in the cellulolytic activity of all tested bacterial isolates at 100 ppm. The latter was considered a fatal dose for the Amitermes vilis termite.

Keywords:

Amitermes vilis termite , endosymbionts , essential oil , mineral compound , cellulolytic activity