Distribution and abundance of aerobic anoxygenic phototrophic bacteria in the tropical coastal waters of Gunungkidul, Yogyakarta, Indonesia

Aprilyanto V, Sembiring L, Djohan TS. 2020. Distribution and abundance of aerobic anoxygenic phototrophic bacteria in the tropical coastal waters of Gunungkidul, Yogyakarta, Indonesia. Biodiversitas 21: 5506-5513. Aerobic anoxygenic phototroph (AAP) is a community of bacteria capable of performing anoxygenic photosynthesis in the presence of oxygen. AAP abundance in most oceanic regions signals its ecological importance in marine microbial loop. This study was conducted to reveal the distribution and abundance of AAP in Siung coast, Gunungkidul, Yogyakarta, Indonesia. Total bacterioplankton and AAP were enumerated using acridine orange direct count (AODC) and real-time quantitative PCR (qPCR), respectively. Several water physicochemical parameters as well as dissolved nitrate, ammonium, phosphate, and sulfate were also measured. The results showed that total bacterioplankton was distributed thoroughly in the water column with abundance ranging from 2.5×104 to 3.5×104 cells/mL. Within this total bacterioplankton, AAP ranged from 3.83×102 –7.48×102 cells/mL, comprising about 1% to ~2.5%. Inorganic nutrient concentration, mainly nitrate and phosphate were thought to be the regulating factors to the distribution and abundance of both communities. In conclusion, AAP comprises a relatively low portion of the total bacterioplankton community in the tropical coastal water in Gunungkidul, Yogyakarta.

Abundance and Spatial Distribution of Aerobic Anoxygenic Phototrophic Bacteria in Tama River, Japan

Aerobic anoxygenic phototrophic bacteria (AAnPB) are widely distributed and regarded as key players driving the carbon cycle in surface water of global oceans, coastal and estuary areas and in other freshwater environments (e.g., ponds and lakes). However, the abundance and spatial distribution of AAnPB in rivers is much less well-known. Here we investigated the variation of the absolute cell abundances of the total bacteria, AAnPB and cyanobacteria, at four different sites in Tama River, Japan, and the spatial distribution (i.e., free-living or particle-attached existence form) of AAnPB at two out of the four sites using infra-red epifluorescence microscopy. Free-living cell abundances for the total bacteria, AAnPB and cyanobacteria were 1.6–3 × 105, 1.5–4.4 × 104 and <3.2 × 104 cells mL−1, respectively. The free-living AAnPB accounted for 6.1%–19.6% of the total bacterial abundance in the river. The peaks of the AAnPB and cyanobacteria abundances were found at the same site, suggesting that the AAnPB could potentially coexist with cyanobacteria. Meanwhile, the particle-attached AAnPB were observed at the two sites of the river, accounting for 52.2% of the total bacteria abundance in the particle. Our results showed the existence and aggregation form of AAnPB in the riverine environment.