Table 2. Percentages of the shared genera and their corresponding sequences.

Number of samplea	Number of shared genera	Percentage in classified generab	Percentage in classified sequencesc
15	70	9.5	63.7
14	121	16.4	81.2
13	158	21.4	86.5
12	184	24.9	89.3
11	208	28.1	91.0
10	235	31.8	92.7
9	253	34.2	93.6
8	278	37.6	94.0
7	305	41.3	94.5
6	339	45.9	97.3
5	373	50.5	97.7
4	404	54.7	98.4
3	468	63.3	99.1
2	556	75.2	99.7
1	739	100.0	100.0

Abbreviation: AS, activated sludge.

Among the 744 assigned genera, 70 (accounting for 63.7% of the classified sequences) were shared by all 15 samples. A total of 235 genera were commonly shared by more than 10 AS samples, accounting for 92.7% of all classified sequences. There were 273 rare genera that only appeared in one or two samples, accounting for only 0.9% of total sequences.

^aNumber of AS samples, which share the genera in the second column.

^bPercentage of the number of shared genera in the number of total classified genera.

^cPercentage of sequences of the shared genera in the total classified sequences.