An Alkaliphilic and Xylanolytic Paenibacillus Species Isolated from the Gut of a Soil-Feeding Termite

Abstract

Gut portions of soil-feeding termites belonging to the subfamily Termitinae generally show extensive alkalinity. An alkaliphilic and xylanolytic bacterium, strain SM-XY60, was isolated from the gut of such a soil-feeding termite Sinocapritermes mushae. This bacterium was a strictly aerobic endospore-forming rod, capable of growth at pH 6.5 to 10.5, and showing optimal growth at pH 9. The strain grew well on an alkaline medium containing K2CO 3, but not Na2CO3. 16S rDNA analysis and physiological characterization revealed this strain to be a member of the genus Paenibacillus but distinct from any known species. The xylanase produced by the alkaline growing cells showed substantial activity and stability at high pH, implying an adaptation of the enzyme to the gut alkaline environment. The isolation of this alkaliphile suggests that the insect gut is of ecological significance for alkaliphiles.