Distribution of Phototrophic Purple Nonsulfur Bacteria in Activated Sludge Systems and Other Aquatic Environments

Abstract

Purple nonsulfur bacteria occurred in relatively high numbers (105 to 107 viable cells/m/) in surface waters of ditches, paddy fields, and tide pools under oxygen-limited conditions, whereas they were absent or found in small numbers in eutrophic pond and river waters in which too much oxygen was present. The phototrophic bacteria were recovered from all activated sludge plants studied, with numbers of 102 to 105 viable cells/mg dry sludge. In general, food industrial wastewater activated sludge samples yielded higher numbers of the phototrophic bacteria than did sewage activated sludge samples. These results suggest that the organic nutrient composition of the waste is an important factor controlling the occurrence of these bacteria in activated sludge. The phototrophic bacterial flora of the activated sludge and the other aquatic environments was mainly represented by facultatively aerobic species such as Rhodopseudomonas sphaeroides, Rhodopseudomonas palustris, Rhodopseudomonas eelatinosa, and Rhodopseudomonas capsulata. © 1984, The Japanese Society of Fisheries Science. All rights reserved.