The Rana chensinensis widely distributed in Qinling Mountains were liable to be infected in Dayukou (region A, 109°6′52″E, 34°0′56″N) than Shibianyu (region B, 108°56′33″E, 34°0′20″N). Six microorganisms were isolated from the infected Rana chensinensis at region A, among which, Aeromonas hydrophila is a strong pathogen to Rana chensinensis according to the data from artificial infections. The bacteria-community structures of two regions were analyzed by PCR-DGGE (PCR-denaturing gradient gel electrophoresis), and the quality of water was examined. The results showed that a rich bacteria diversity was found in the soil and water from both region A and B, but there were significant differences between A and B. Meanwhile, the content of six strains isolated from Rana chensinensis in A and B was different, and the population of Aeromonas hydrophila in region A was richer than that of region B. Particularly, several strains highly homologous with the stains identified from sewerage were isolated at region A. The water quality analysis indicated that the water quality of region A is lower than that of region B. So, the deterioration of environment at region A was assumed to be the major causation for the infection of the wild Rana chensinensis.

Rana chensinensis; pathogen; PCR-denaturing gradient gel electrophoresis; bacteria-community