Community Structure Of Symbiotic Microorganisms&Diversity Of The Culturable Aerobic And Facultative Anaerobic Bacteria From Different Intestinal Compartments Of Nasutitermes Hainanensis

Termites are closely related to the human life and society.There are many species in nature.And many of them can degrade cellulose and hemicellulose efficiently.It is assumed that symbiotic microorganisms play important roles in the degradation of lignocellulose,and the complex symbiotic association between microorganisms and termites is one of the most fascinating topics in this field.Nasutitermes distribute in tropical and subtropical regions widely.As a representative of wood-feeding higher termites,it is a good model for the study of the symbiotic association between termites and their gut microorganisms.In this paper,we studied the bacterial community structure and composition of different intestinal compartments of Nasutitermes hainanensis by 16S rRNA Pyrosequencing and made efforts to cultivate symbiotic bacteria from the termite gut by imitating the intestinal physiochemical conditions.All these studies will lay the foundation for elucidating the symbiotic mechanisms between wood-feeding termites and their gut microorganisms.The main results of this study are as follows:1.16S rRNA Pyrosequencing was used to analyze the community structure and composition of symbiotic microorganisms of different intestinal compartments of Nasutitermes hainanensis,namely,the crop,midgut and four major hindgut compartments(P1,P3,P4,P5).The statistics of pyrosequencing data showed that the diversity of symbiotic bacteria of P4 compartment was the highest.And the dominant bacterial composition of P1,P3,P4 compartments is similar,which may be associated with physiochemical conditions of these intestinal compartments and the similar functions of these bacteria in different intestinal compartments.The analysis of symbiotic bacterial composition of different gut sections based on phylum level showed that the main bacteria in the crop were Proteobacteria(32.91%),Spirochaetes(17.93%);the main bacteria in midgut were Firmicutes(34.89%),Spirochaetes(25.88%)and Proteobacteria(12.07%);the dominant bacteria in P1 compartment were Spirochaetes(58.83%),Fibrobacteres(12.58%);the dominant bacteria in P3 compartment were Spirochaetes(65.42%),Fibrobacteres(18.12%);the dominant bacteria in P4 compartment were Bacteroidetes(26.56%),Spirochaetes(35.70%),Fibrobacteres(10.93%);and the main bacteria in P5 compartment were Proteobacteria(31.39%),Bacteroidetes(15.98%)and Spirochaetes(34.98%),respectively.2.Three media(1/3TSB,MM,GYM)with different pH were used to isolate bacterial symbionts from 6 different gut sections(the crop,midgut,hindgut compartments P1,P3,P4,P5)of Nasutitermes hainanensis under aerobic conditions.In total 588 aerobic and facultative anaerobic bacterial strains were isolate and identified based on morphological characteristics and the sequences of 16S rRNA genes.All these 588 bacterial strains belong to 25 genera(Stenotrophmonas,Microbacterium,Ochrobacterium,Lactococcus,Enterococcus.etc.).The analysis showed that the highest abundance of bacteria were isolated from P3 compartment,which occupied 22.1%of the total bacterial isolates.Among different gut compartments,the highest diversity of bacteria isolates were from P4,from which bacteria afffiliated with 18 genera were isolated.The dominant bacteria isolated from the crop were affiliated with the genera Acinetobacter,Stenotrophmonas,Lactococcus;While the dominant bacteria isolated from midgut were Acinetobacter,Stenotrophmonas,Lactococcus,Ochrobactrum;And the dominant bacteria from P1 were Microbacterium,Stenotrophmonas,Sphingomonas;The dominant bacteria from P3 were Stenotrophmonas,Enterococcus,Lactococcus,Acinetobacter;from P4 were Microbacterium,Stenotrophmonas,Lactococcus;from P5 were Microbacterium,Paenibacillus,Lactococcus,respectively.The most dominant bacteria were those affiliated with the genus Lactococcus,which account for 19.2%of the total bacterial isolates.And bacteria belonged to the genus Stenotrophmonas were the second most dominant isolates.Two of the Lactococcus isolates are possible new species since their 16S rRNA gene sequence shared similarity lower than 97%compared with all the other bacteria in GenBank database.