| Termites, especially in tropical and subtropical regions, are important decomposers and play a vital role in the recycling of lignocellulose. In the termite gut there are abundant and variety kinds of microbes, these intestinal microbes are considered to contribute to play essential roles in digestion and absorption of lignocellulose; what’s more, this symbiotic relationship are also be useful to study the evolution of termite’s social behavior. In addition, this mutualistic symbiotic relationship is not only beneficial to the hosts, but also be good for the guts’microbes. These symbiotic relationship form complex symbiotic network, which is thought to play critical role in degradaing efficiently lignocellulose. Therefore, it’s significant to understand the intestinal symbiotic system.In this article, we chose two different types of wood-feeding termites as the study objects:a lower wood-feeding termite, Reticulitermes chinensis Snyder, and a higher wood-feeding termite, Nasutitermes sp. In order to isolate and purify culturable anaerobic and falcultative anaerobic bacteria from the termite gut, six different media were adopted. The comparative study will help us to understand the function and structure of symbiotic microbes in wood-feeding termites and to clarify the mechanisms of cellulose biodegradation by wood-feeding termites. The main results can be described as follows:1. Based on the medium of1/3TSB, the MPN counting of culturable anaerobic and falcultative anaerobic bacteria in the gut of Nasutitermes sp. indicated that every Nasutitermes sp harbour about1.10X105culturable anaerobic and falcultative anaerobic bacteria; Based on the medium of PY②, the MPN counting of culturable anaerobic and falcultative anaerobic bacteria in the gut of Nasutitermes sp. indicated that the amount of culturable anaerobic and falcultative anaerobic fibrobacteres was1.25X104.2. Six media, including TSB, LB, PY①, PM①and so on, were employed to isolate and purify culturable anaerobic and falcultative anaerobic bacteria from the Nasutitermes sp. gut. In total55bacterial strains were isolated and purified from the gut of Nasutitermes sp. According to phylogenetic analysis of the16S rRNA genes sequences analysis of the representatives strains, these55bacterial strains belong to11distinct genera, in which22%of the isolated srains belong to Lactococcus, occupies obvious predominant position; Pseudomonas are also main flor that account for18%of the total isolate srains separately. Besides, bacteria affiliated with Citrobacter and Trabulsiella, Clostridium also occupy a higher proportion, account for13%,11%and9%respectively. Other isolated strains contain Enterobacter, Enterococcus, Staphylococcus, Paenibacillus and so on.3. Based on MPN counting, the number of culturable anaerobic and falcultative anaerobic bacteria on1/3TSB medium in the gut of Reticulitermes chinensis Snyder was3.55×104.4. In total66culturable anaerobic and falcultative anaerobic bacterial strains were isolated and purified from the gut of Reticulitermes chinensis Snyder based on three kinds of media, including TSB、LB、PY②. According to phylogenetic analysis of the16S rRNA genes of the representatives strains, these66bacterial strains belong to7distinct genera. Quantitatives analysis indicated that39%of the bacterial strains was Enterobacter, which was absolutely predominant in the culturable anaerobic flora; Strains belong to Citrobacter were the second dominant bacteria, whose proportion was30%. In addition, bacteria affiliated with Pseudomonas and Yokenella also occupy a higher proportion, account for15%and6%, respectively. Other isolated strains contain Staphylococcus, Bacillus and Lactococcus.Comparative analysis showed that the diversity and the structure of population from the two terimtes have significant difference. For example, bacteria belonged to Trabulsiella, Clostridum, Paenibacillus, Bacteroidetes can’t be found in the gut of Reticulitermes chinensis Snyder. Whereas bacteria belonged to Yokenella can’t be found in the gut of Nasutitermes sp. Compared with the bacterial diversity reported from other termites, we speculated that the difference of diversity of culturable anaerobic and facultative anaerobic bacteria between the two termites may be related to the physiological and biochemical conditions of intestinal tract, the mechanisms of cellulose degradation, as well as whether or not the presence of gut flagellates.In addition, a bacterial strain (TS-14), isolated from Reticulitermes chinensis Snyder, was characterized by morphology, physiology and biochemistry. The cells of TS-14were Gram-negative, straight rods (approximately1-2μm long and0.5μm wide). Colonies was spherical, damp, milk white, opaque, shiny, smooth. The bacterial cells had no flagellum and were unmotile. The optimal culture conditions was described as follows:TS-14can grow in maximum salt concentration of1.5%. When the concentration of salt is greater than1.5%, no growth occurred. Growth occurred at pH3.5-10.0(optimum,5.5) and15℃-40℃(optimum,30℃). The DNA G+C content of strain TS-14was67.67mol%. On the basis of morphological, physiological and biochemical characteristics, content of (G+C) mol%and16S rRNA gene sequences, strain TS-14was identified as belonging to the Burkholderia mallei of the genus Burkholderia. |
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