Molecular Identification Of The Intestinal Bacterial Community Of Mythimna Separata(Walker)Larvae

Mythimna separata (Noctuidae, Lepidoptera) is an imporant test insect in pesticide toxicology. The intestinal bacteria play an imporant in physiological and biochemical reaction, immunology, resistance to disease and deintoxication. The changes of intestinal microbiol could reflect the state of body’s physiological function and the reaction conditions of gut microflora environment to pesticide. In the present paper, the detailed analysis of bacterial diversity and community structure in the gut of the M. separata was reported, through the construction of16S rDNA clone libraries, polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) and culture-dependent techniques. The objective of this study is to document the bacterial community structure and diversity in M. separata for providing some theories for the pesticide influence on the intestinal bacteria community.The results showed:①Nine different bacterial strains were isolated, Slaphylococcus was the dominant component and other strains belonged to the genera Bacillus, Arthrobacter and Enterococcus in culture-dependent techniques.②Through construction the16S rDNA gene clone library gained Escherichia,Synechococcus, Beta proteobacterium, Pseudomonas, Ochrobactrum anthropi, Ralstoni, Enterococcus, and Escherichia was the dominant bacteria.③Five know bacteria were obtained by PCR-DGGE, they were Escherichia, Staphylococcus, Enterococcus, Pantoea, Pseudomonas, and Enterococcus and Pseudomonas was the predominant bacteria.Concluntion:The intestinal bacteria of M. separata obtained from construction of gene library were more than that of DGGE and culture-dependent, which indicated construction of gene library showed a higher bacterial diversity than DGGE and culture-dependent. The bacteria which isolated by three methods were not totally same, such as Arthrobacter was only detected in culture-dependent technique, Ralstoni was only obtained in clone and Pantoea just got by PCR-DGGE.Three methods showed different predominant bacteria, this mainly related to advantage and disadvantage of each method. Therefore, culture-independent and culture-dependent techniques should be combined effectively so that the composition of microbial community structure and diversity could be better revealed.