Cadaverine and putrescine exposure influence carbon and nitrogen cycling genes in water and sediment of the Yellow River

The response patterns of microbial functional genes involved in biogeochemical cycles to cadaver decay is a central topic of recent environmental sciences.However,the response mechanisms and pathways of the functional genes associated with the carbon(C)and nitrogen(N)cycling to cadaveric substances such as cadaverine and putrescine remain unclear.This study explored the variation of functional genes associated with C fixation,C degradation and N cycling and their influencing factors under cadaverine,putrescine and mixed treatments.Our results showed only putrescine significantly increased the alpha diversity of C fixation genes,while reducing the alpha diversity of N cycling genes in sediment.For the C cycling,the mixed treatment significantly decreased the total abundance of reductive acetyl-CoA pathway genes(i.e.,acsB and acsE)and lig gene linked to lignin degradation in water,while only significantly increasing the hydroxypropionate-hydroxybutylate cycle(i.e.,accA)gene abundance in sediment.For the N cycling,mixed treatment significantly decreased the abundance of the nitrification(i.e.,amoB),denitrification(i.e.,nirS3)genes in water and the assimilation pathway gene(i.e.,gdhA)in sediment.Environmental factors(i.e.,total carbon and total nitrogen)were all negatively associated with the genes of C and N cycling.Therefore,cadaverine and putrescine exposure may inhibit the pathway in C fixation and N cycling,while promoting C degradation.These findings can offer some new insight for the management of amine pollution caused by animal cadavers.

Two community types occur in gut microbiota of large-sample wild plateau pikas(Ochotona curzoniae)

Studies on large-sample gut microbial sequencing data indicate that gut microbiota can be divided into multiple community types;different community types may influence the community function and ecosystem service.However,the knowledge on the classification,diversity,interaction,and assembling of microbial community types in the gut of wild animals is still insufficient.Here,we used pika gut microbiota data as an example to study the microbial community types in large-sample sequencing dataset.Cecal microbial communities from 118 wild plateau pika(Ochotona curzoniae)individuals at 5 elevational regions on the Qinghai–Tibet Plateau were analyzed.Our results show that pika gut microbiota can be separated into 2 community types(Cluster I and Cluster II).Cluster I was mainly distributed on the high-elevation regions with more than 3694 m and was most dominated by Firmicutes.Cluster II was from the low-elevation areas(lower than 3580 m),and was predominated by Bacteroidetes.Cluster I had a higher community alpha-diversity and predicted functional diversity than Cluster II,and the betadiversity and predicted functional profiles of these 2 clusters were significantly different.Network analysis revealed that there were more complex interactions between Cluster I,which had enhanced influence on the co-occurrences of other microbes in the bacterial community when compared to Cluster II.Phylogenetic analysis found that the environmental filtering in the Cluster I was stronger than Cluster II.The assemblages of pika gut bacterial communities were determined mainly by deterministic processes,while the relative importance of deterministic processes accounted for more percentages in the Cluster I than Cluster II.Our results demonstrated that 2 gut microbial community types in pikas had distinct diversity patterns and ecological functions.Current methods are also helpful for identifying gut community types and the related mechanisms behind gut microbiota types in large-sample sequencing data of wild animals.