Abundances of ammonia-oxidizing archaeal accA and amoA genes in response to NO2 － and NO3－ of hot springs in Yunnan province

Abstract:

Abstract:［Objective］Yunnan hot springs have highly diverseammonia-oxidizing archaea (AOA)，which are autotrophic and can fix CO2 using the 3-hydroxypropionate/4-hydroxybutyrate (HP/HD) pathway．In this study，we investigated the abundances of prokaryotic 16S rRNA gene and archaeal accA and amoA genes in the sediments of hot springs of Yunnan Province，and analysed the correlations between the above gene abundances and environmental factors.［Methods］We selectedthe sediments of twenty representative hot springs，anddetected the gene abundances by quantitative polymerase chain reaction (qPCR)．The principal component analysis (PCA) and the Mantel test in the R software package were performed for the correlations of gene abundance and environmental variables.［Results］The bacterial and archaeal 16S rRNA gene abundances were from 6.6×107 to 4.19 × 1011 and from 1.27×106 to 1.51×1011 copies/g sediment，respectively; Archaeal accA and amoA genes were from 8.89×103 to 6.49×105 and from 7.64×103 to 4.36×105 copies/g sediment，respectively. The results of mantel test showed that accA gene was significantly (R=0.98，P＜0.001) correlated with amoA gene; Both of them also were correlated significantly with NO2－and NO3－，but not with pH.［Conclusion］The abundances of bacterial and archaeal 16S rＲNA genes and the ratio between them varied significantly among Yunnan hot springs． The archaealaccA and amoA genes showed significant correlation with each other，validating our previous finding that AOA in terrestrial hot springs might acquire energy from ammonia oxidation coupled with CO2 fixation using the 3-hydroxypropionate/4-hydroxybutyrate pathway.