The Diversity and Extensive Presence of Culturable Anoxygenic Phototrophic Bacteria in Manitoba Marshes

Marshes are an important ecosystem, acting as biodiversity hotspot, a carbon sink as well as a bioremediation site, breaking down anthropogenic waste such as antibiotics, metals and fertilizers. For participating in these metabolic activities and their capability to contribute to primary productivity, microorganisms in such habitats have become of interest to investigate. Since Proteobacteria were previously found to be abundant, and the waters are well-aerated and organic-rich, this study on the presence of anoxygenic phototrophic bacteria, purple non-sulfur bacteria or aerobic anoxygenic phototrophs in marshes was initiated. Samples were collected at 7 Manitoban sites and anoxygenic phototrophs were cultivated and preliminary enumerated. A group of 14 strains, which represented the phylogenetic diversity of the isolates was further physiologically investigated. Aerobic anoxygenic phototrophs and purple bacteria were present at each location and they belonged to the α- and β-Proteobacteria subphyla. Some were closely related to known heavy metal reducers (Brevundimonas) and xenobiotic decomposers (Novosphingobium, Sphingomonas). All were able to synthesize the photosynthetic complexes aerobically. This research highlights the diversity and potential contribution’s anoxygenic phototrophs make to the essential functions taking place in wetlands.