Molecular Physiology of Anaerobic Phototrophic Purple and Green Sulfur Bacteria

Abstract

There are two main types of bacterial photosynthesis: oxygenic (cyanobacteria) and anoxygenic (sulfur and non-sulfur phototrophs). Molecular mechanisms of photosynthesis in the phototrophic microorganisms can differ and depend on their location and pigments in the cells. This paper describes bacteria capable of molecular oxidizing hydrogen sulfide, specifically the families Chromatiaceae and Chlorobiaceae, also known as purple and green sulfur bacteria in the process of anoxygenic photosynthesis. Further, it analyzes certain important physiological processes, especially those which are characteristic for these bacterial families. Primarily, the molecular metabolism of sulfur, which oxidizes hydrogen sulfide to elementary molecular sulfur, as well as photosynthetic processes taking place inside of cells are presented. Particular attention is paid to the description of the molecular structure of the photosynthetic apparatus in these two families of phototrophs. Moreover, some of their molecular biotechnological perspectives are discussed.

Characterization of the First Cultured Representative of “ Candidatus Thermofonsia” Clade 2 within Chloroflexi Reveals Its Phototrophic Lifestyle

“…Light is ubiquitously distributed in diverse environments, including the deep ocean (e.g., geothermal light and bioluminescence) ( 2 , 3 ). Accordingly, phototrophic and nonphototrophic microbes have evolved different sophisticated light utilization systems to harness light for survival through photosynthetic apparatuses ( 4 ) and photosensors ( 5 ), respectively. There are two types of bacterial photosynthesis: oxygenic (cyanobacteria) and anoxygenic (sulfur and nonsulfur phototrophs) ( 4 ).…”

“…Accordingly, phototrophic and nonphototrophic microbes have evolved different sophisticated light utilization systems to harness light for survival through photosynthetic apparatuses ( 4 ) and photosensors ( 5 ), respectively. There are two types of bacterial photosynthesis: oxygenic (cyanobacteria) and anoxygenic (sulfur and nonsulfur phototrophs) ( 4 ). Since the first observation of anoxygenic photosynthesis, eight bacterial phyla (including Cyanobacteria , Chloroflexi , Proteobacteria , Firmicutes , Chlorobi , Acidobacteria , Gemmatimonadetes , and “ Candidatus Eremiobacterota”) have been reported to conduct an anoxygenic phototrophic lifestyle ( 6 ).…”

Electron Transfer in the Biogeochemical Sulfur Cycle

“…They are important in the sulfur cycle and as primary producers in environments with high sulfur concentrations, ones which can oxidize sulfide, thiosulfate, and elemental sulfur for photosynthetic growth (anoxygenic photosynthetic CO 2 fixation) [74]. Green sulfur bacteria contain dissimilatory sulfite reductase genes and are capable of oxidizing elemental sulfur, thiosulfate, and sulfide [75,76]. Purple sulfur bacteria can also use organic compounds, making them facultative photolithotrophs [67].…”

Diversity of Prokaryotic Microbiota in Iloilo River, Iloilo Province, Philippines Through Partial 16S rrna Gene Sequence Analysis

“…Rhodobacteraceae a Gram-negative bacterium and previously known as photoheterotrophs and chemoheterotrophs purple non-sulfur bacteria deeply involved in sulfur and carbon biogeochemical cycling and symbiosis [36,37]. On the other hand, Chromatiaceae is a group of purple sulfur bacteria, and their occurrence signifies the presence of elemental sulfur in the environment [38,39].…”