FIG 3.

UPGMA cluster tree constructed based on the 97% cutoff level-based unweighted Unifrac matrix. Microbial groups with an abundance greater than 2% are displayed. Groups with abundances lower than 2% were included as “Others,” which include Nitrosovibrio and Nitrosomonas clusters 6 and 8. (A) AOB; (B) AOA. For AOB, the previously published nomenclatures of Nitrosospira clusters 0, 1, 2, 3a, 3b, 4, 9, 10, 11, and 12 (7, 8) and Nitrosomonas clusters 5, 6a, 6b, 7, and 8 (9) were used; for AOA, the previously published nomenclatures of Nitrosopumilus, Nitrososphaera, Nitrosocaldus, and Nitrosotalea subclusters and Nitrososphaera sister cluster (23) were used.