关键词: 美洲大蠊, 戈登菌, 16S rDNA, 系统发育学

Abstract:

Objective To isolate Gordonia from the gut of Periplaneta americana, and to carry on classification, identification and phylogenetic analysis on the Gordonia. Methods Taking the gut was acquired from captured P. americana by opening the abnormal with scalpel from the side after surface disinfection. After grinding, the homogenate was be diluted to the required concentration (10, 0.005, 0.0025 μg/ml). An aliquot of 0.1 ml was drawn on the tablet, and cultured at 28℃ for at least one week, to isolate the Gordonia. Finally, morphological observation and 16S rDNA gene sequences analysis were utilized to study their classification and identification. The sequence data were analyzed using Mega 5.1 software, maximum likelihood method, and phylogenetic tree. Results Six Gordonia were isolated and identified from the gut of wild P. americana. The gram stain was positive, the colonies were small, orange red, granular, the slightly wetsurface, with production of orange red pigment. The thalli was short rod. The mycelium was straight rod or spiral, without transverse septum, consistent with the basic characteristics of Gordon's bacteria. After the amplification of 16S rDNA gene, 1% agarose gel electrophoresis, six samples all showed target bands (1.5 kb), the sequencing results showed that the isolates were Gordonia. Phylogenetic tree analysis showed that the isolates obtained were close to the Gordon's genetic relationship in soil, plant and marine. Conclusion There is existing Gordonia in the gut of P. americana. The Gordonia isolated from soil, plants and marine have the function of degrading the biological macromolecules and absorbing heavy metals, which can lay foundation for further study of symbiont flora in P. americana.

Key words: Periplaneta americana, Gordonia, 16S rDNA, Phylogenetic