Revisiting methanotrophic communities in sewage treatment plants

Abstract

The methanotrophic potential in sewage treatment sludge was investigated. We detected a diverse aerobic methanotrophic community that potentially plays a significant role in mitigating methane emission in this environment. The results suggest that community structure was determined by conditions specific to the processes in a sewage treatment plant.

Fig 1

Cluster analysis of standardized microarray data showing the diversity of the aerobic methanotrophic community in wastewater sludge after incubation. Probe names and their intended specificities are shown (see Table S1 in the supplemental material). The results shown are averages of triplicate analyses of each sludge sample. Red and blue indicate the highest and no hybridization signal, respectively. These probes represent type I and II methanotrophs. Probes targeting amoA (a gene encoding ammonia monooxygenase), pmoA2, verrucomicrobial methanotrophs, and environmental sequences clustered between amoA and pmoA are grouped as “Others.”

Fig 2

qPCR analysis of MBAC, MCOC, and TYPEII assays in the starting materials (A) and after 12 days of incubation (B). qPCR was performed in duplicate with each DNA extract (mean ± standard deviation, total n = 6).

Fig 3

Phylogenetic tree depicting NC10 bacterial diversity in different compartments of STPs based on pmoA gene sequences. Clustering of nucleotide sequences (351 positions) was inferred by using the neighbor-joining algorithm integrated in MEGA5 (45). Bootstrap support values (1,000 replicates) of greater than 50% are indicated at the nodes. The analysis involved 158 pmoA, amoA, and pxmA gene sequences, but for clarity, they were grouped as shown. The scale bar shows the number of base differences between sequences.