Gut of Higher Termites as a Niche for Alkaliphiles as Shown by Culture-Based and Culture-Independent Studies.

Abstract

We screened alkaliphilic bacteria from the first proctodaeal region (P1) of the hindgut, which is known to show high alkalinity and K + richness, of several species of higher termites. Phylogenetic analyses based on the 16S rDNA sequence revealed that most isolates were affiliated with known alkaliphilic bacilli, frequently isolated from soil. Though many physiological characteristics of the isolated strains were similar to those of soil alkaliphilic bacilli, some strains showed a distinctive NaCl sensitivity. Many strains grew better in an alkaline medium containing K 2 CO 3 than one containing Na 2 CO 3 . One strain, closely related to the xylanolytic and alkaliphilic Paenibacillus sp. SM-XY60 from the soil-feeding termite Sinocapritermes mushae, was also isolated. Culture-independent analysis showed that bacteria closely related to our isolated alkaliphiles widely inhabit the termite gut. Our results also suggested that some alkaliphilic bacilli in soil share ecological niches in the termite gut.

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

“…Xylanase activity in the culture medium was measured (solid squares). accompanying paper 39) , some of the alkaliphiles isolated from several termite species indeed preferred K + to Na + for their growth.…”

“…Although Brune 7) mentioned the presence of a number of alkaliphiles in extremely alkaline gut regions, no taxonomic or physiological description of them was given. In the accompanying paper 39) , the presence of Paenibacillus species related closely to strain SM-XY60 was revealed in the gut of some Termitinae termites in Thailand by culture-based and culture-independent analyses. The species represented by strain SM-XY60 is probably shared by some members of the subfamily Termitinae whose guts have extreme alkaline regions.…”

“…Here, we report the physiological characterization of an alkaliphilic and xylanolytic Paenibacillus strain isolated from the gut of a soil-feeding termite, and also describe some properties of the xylanolytic enzyme produced by this strain. Along with an accompanying report 39) , the isolation of alkaliphiles suggests that the insect gut is of significance to the ecology of alkaliphiles.…”

Isolation and Detection of Methanogens from the Gut of Higher Termites

“…In fact, some alkaliphilic bacteria related to Bacillus and Paenibacillus have been identified in the gut of higher termites 17,21) . The alkaline gut contents are also known to be rich in K + rather than Na + and many alkaliphiles isolated from the termite gut show a preference for K + for their growth 17,21) . The methanogen isolates, however, showed neither an alkaliphilic feature nor a strong preference for K + .…”

Alkalibacterium psychrotolerans sp. nov., a psychrotolerant obligate alkaliphile that reduces an indigo dye

“…This might due to the fact that niches for alkaliphiles are relatively small, e.g. the intestines of insects (high pH), and are distributed throughout natural ordinary environments (Thongaram et al, 2003). Alkaliphilic bacteria can be either facultative or obligate (Krulwich & Guffanti, 1989).…”