Structure Dynamics Of Gut Microbiota Of Pelophylax Nigromaculatus In Rice-frog Co-cultivation Mode

Pelophylax nigromaculatus,with its high nutritional and economic value,has been increasingly favored by farmers.In view of the disadvantages of intensive cultivation,people began to adopt ecological breeding methods in recent years,such as rice-frog co-cultivation mode.The gut microbiota is important for the nutritional health and growth of animals,so the analysis of the structure of gut microbiota of P.nigromaculatus at different life history stages will help to elucidate the growth advantages and disadvantages of P.nigromaculatus under the rice-frog co-cultivation mode.Through experiment on developing the rice-frog co-cultivation,this study investigate the growth situation of P.nigromaculatus in the whole process of cultivation,and based on 16 S r RNA gene amplification sequencing technology,parsing the structure and succession of gut microbiota of P.nigromaculatus at different developmental stages(including abnormal developmental stage,subadult-adult stage,hibernation stage),and examine the differences of gut microbiota of P.nigromaculatus between genders at subadult-adult stage.The main research results are as follows:(1)From hind limb stage to juvenile stage,the body weight of P.nigromaculatus decreased continuously,and the body weight of P.nigromaculatus at juvenile stage decreased by 23.5% compared with that at hind limb stage.The snout-vent length of forelimb stage and hind limb stage were similar,but the snout-vent length of juvenile stage increased by 8.8% compared with that at forelimb stage.After the completion of metamorphosis,the growth of both males and females was rapid,but the growth of both males and females tended to be stable after maturity.The growth rate of males may be higher than that of females at subadult stage,while the growth rate of females may be higher than that of males at adult stage.(2)The α-diversity level(Sobs,Chao1,Shannon and Simpson index)of gut microbiota at forelimb stage and juvenile stage was significantly lower than that at hind limb stage,subadult stage and adult stage.The β-diversity of gut microbiota of P.nigromaculatus was significantly different throughout different developmental stages.Proteobacteria and Pseudomonadaceae were dominant at hind limb stage,forelimb stage and juvenile stage.From the hind limb stage to the juvenile stage,the relative abundance of Proteobacteria and Pseudomonadaceae increased first and then decreased,and reached the highest at forelimb stage.From the subadult stage to the adult stage,the relative abundance of Proteobacteria and Pseudomonadaceae decreased,while the relative abundance of Firmicutes increased,and Firmicutes was dominant at adult stage.There were gut bacterial groups with significant differences in relative abundance between genders.(3)Compared with non-hibernation,the Shannnon and Simpson index of gut microbiota of hibernating P.nigromaculatus were significantly decreased.The β-diversity of the gut microbiota of P.nigromaculatus was significantly different before and after hibernation.Firmicutes were dominant in non-hibernating P.nigromaculatus.Compared with non-hibernation,the relative abundance of Firmicutes decreased,while the relative abundance of Proteobacteria and Pseudomonadaceae increased in the prehibernation stage and mid-hibernation stage.Proteobacteria and Pseudomonadaceae were dominant in the mid-hibernation stage.In conclusion,the gut microbiota of P.nigromaculatus is in dynamic changes under the rice-frog co-cultivation mode,and these changes may help the host to adapt to the complex changes of life history.