Changes in rhizobacterial community mediating atrazine dissipation by arbuscular mycorrhiza

Although it was well known that arbuscular mycorrhizal fungus (AMF) inoculation significantly increased atrazine dissipation in the soil, the effect of AMF on bacterial community, especially potential atrazine-degrading bacteria mediating atrazine dissipation has been overlooked. In the present study, there were four different treatments: Funnelliformis mosseae inoculation with or without atrazine; and non-AMF inoculation with or without atrazine. F. mosseae significantly increased atrazine dissipation rate from 28.7% to 53.3%. Then 16S rRNA gene sequencing results indicated that bacteria community differed significantly by F. mosseae inoculation and atrazine addition. The Shannon index decreased significantly with AMF and atrazine at phylum and family level, and significant inhibition of atrazine on evenness was also observed. LEFSe analysis revealed that Terrimonas and Arthrobacter were significantly associated with F. mosseae, as well as unidentified_Nitrospiraceae associated with atrazine addition. There are several bacterial taxa associated with both F. mosseae inoculation and atrazine addition. Totally, twelve atrazine-degrading bacterial genera (>0.10%) were identified. When atrazine was added, the abundance of Arthrobacter, Burkholderia, Mycobacterium and Streptomyces increased in F. mosseae inoculation treatment, but Nocardioides, Pseudomonas, Bradyrhizobium, Rhizobium, Rhodobacter, Methylobacterium, Bosea and Shinella decreased. In the presence of atrazine, activities of dehydrogenase, urease, acid and alkaline phosphatase in F. mosseae inoculation treatment were significantly higher than those in non-inoculation. However, there was no significant relationship between bacterial community and any soil enzyme activity in four treatments. Our findings reveal the potential relationship between soil bacterial community and AMF inoculation during atrazine dissipation.