Spatial and Temporal Succession Characteristics of Aerobic Anoxygenic Photosynthesis Bacteria in a Stratified Reservoir

Abstract

Aerobic anoxygenic photosynthesis bacteria (AAPB) play a significant role in the material circulation of the hydrosphere, with diverse community structure and unique metabolic functions. To investigate the spatial and temporal succession characteristics of AAPB abundance and community structure in Jinpen Reservoir, a quantitative real-time polymerase chain reaction and Illumina MiSeq high-throughput sequencing technique targeting the pufM gene were applied. Furthermore, redundancy analysis was used to determine the influence of environmental factors on their community structure. The results showed that the AAPB abundance ranged from (6.70±0.43)×103 to (2.69±0.15)×104 copies·mL-1, with the maximum value appearing in October, and decreased with an increase in water depth. Samples were mainly classified into 19 genera (except for the unclassified genus); the most abundant AAPB genera were Bradyrhizobium sp. and Methylobacterium sp., which were affiliated to the α-Proteobacteria, and the proportion of the Bradyrhizobium sp. was highest in November, accounting for more than 60% (except 10 m). Furthermore, Rubrivivax sp., belonging to β-Proteobacteria, was found to have a low proportion. There was a strong interaction relationship between AAPB genera. For example, Rhodobacter sp. was positively correlated with Rhodovulum sp., while Hydrogenophaga sp. was negatively correlated with Bradyrhizobium sp.. The community structure composition and distribution of AAPB were significantly different, mainly affected by temperature (T), total nitrogen (TN), NO3--N, and light intensity and comprehensively regulated by environmental factors. For instance, T, TN, and total phosphorus had a significant impact on the AAPB community structure of water samples at 0, 5, and 15 m in October, whereas light intensity, pH, DO, and chlorophyll-a were major structuring factors in the AAPB assemblages of water samples at 5 m in December. The results have guiding significance for parsing the spatial and temporal variability of AAPB abundance and diversity in stratified reservoirs, and simultaneously provide a theoretical basis for exploring the driving factors of AAPB population structure.