Arbuscular mycorrhizal fungi hypha shape atrazine degradation ability of microbiota by increasing soil aggregation.

The s-triazine herbicide atrazine is one of the most widely used herbicides in agriculture. Owing to the relatively high persistence and toxicological effects of atrazine, effective remediation of atrazine-polluted soil is challenging. To date, bioremediation, especially the use of arbuscular mycorrhizal (AM) fungi to remediate atrazine-polluted soil, has received extensive attention because of its prominent dissipation effect. In this study, pot experiments were designed to investigate, in each soil aggregate fraction, how soil bacterial communities and their atrazine-degrading capacity respond to hyphae of an AM fungus (Glomus mosseae). In the presence of G. mosseae hyphae, macroaggregates (> 1 mm) were more abundant, while the number of microaggregates (0.25–1 mm) was significantly decreased. Interestingly, G. mosseae hyphae clearly increased atrazine dissipation in all aggregates except for large macroaggregates (> 2 mm), despite the higher concentration of atrazine residue in smaller soil aggregates. However, G. mosseae hyphae increased the total bacterial biomass and the complexity of the bacterial co-occurrence network. Notably, greater absolute abundances of the atzA, trzN, atzB, trzD and atzE genes in small macroaggregates (1–2 mm) and a higher proportion of this soil fraction were observed simultaneously in the presence of G. mosseae hyphae. At soil aggregate scale, it was indicated that AM fungi hypha significantly enhanced atrazine dissipation, via increasing atrazine-degrading genetic potential of small macroaggregates and its responding proportion.