Niche differentiation of denitrifying anaerobic methane oxidation microbes in Taihu Lake of China

Abstract

Denitrifying anaerobic methane oxidation (DAMO) microbes distribute widely and consume methane/nitrogen in freshwater environments. The survival preference of DAMO microbes directly affects their habitat preference, enabling them playing different roles in different environments. There are few studies regarding the preference and adaptability of DAMO microbes in the environment. In this work, the survival characteristics of DAMO microbes in Taihu Lake were studied. The relative abundance of DAMO archaea was relatively high in samples D7 and D8 of the moderately eutrophic region. The abundance of DAMO bacteria was 1.82 × 10 4 –6.11 × 10 6 copies g − 1 sediment, which was the highest in D1 of the mildly eutrophic region. The microbial association network analysis showed a significant difference in the connector number between the Moderate-NA (54 connectors) and Mild-NA (27 connectors), and DAMO bacteria played the connector role in the Mild-NA. The OTU numbers showing a positive and negative correlation with DAMO bacteria were 7 and 8 in Mild-NA, respectively, while 7 and 10 in Moderate-NA, showing a stronger competition relationship. For DAMO archaea, the corresponding OTUs in Mild-NA were 8 and 5, respectively, while 11 and 2 in Moderate-NA, showing a stronger cooperation association. DAMO microbes were differently affected by the antagonism of Rhodocyclaceae and Anammox bacteria. These results showed that DAMO bacteria and archaea had different survival strategies and displayed niche differentiation in the Taihu Lake. The results expanded our understanding of the ecological functions of DAMO microbes in freshwater and even global environment. • Niche differentiation of DAMO bacteria and archaea in Taihu Lake is evidenced. • DAMO bacteria get suitable niche and become key species in mildly eutrophic region. • DAMO archaea survive more suitably in the moderately eutrophic region. • Rhodocyclaceae and Anammox bacteria cause strong antagonism on DAMO microbes.