Today's review, as you can see, is a summary of the latest developments in sulfur oxidizing bacteria. Compared with SRB, sob uses reduced sulfur as electron donor. According to its energy and growth conditions, sob can be divided into two types: photosulfur bacteria and chemoautotrophic colorless sulfur bacteria.
Photoenergy sob is characterized by sulfur based anaerobic photosynthesis. Under anaerobic conditions, they use light energy to obtain electrons and hydrogen from reductive sulfur compounds, and fix inorganic carbon to promote cell growth. According to the phenotypic characteristics of color, they are mainly divided into green sulfur bacteria (GSB) and purple sulfur bacteria (PSB).
These bacteria usually inhabit the anoxic layer in the aquatic environment with reductive sulfide and light transmittance, or in the salt marshes and marshes of the supratidal zone. All GSBS are strictly anaerobic and photosynthetic autotrophs. Photosynthetic autotrophs, heterotrophies and organic carbon sources are more facultative. Therefore, PSB will exceed GSB when organic load of urban sewage is high. But they all get color and ATP by capturing light absorbing substances such as bacterial chlorophyll and carotenoids.
In addition to GSB and PSB, some phototrophic bacteria do not use sulfur oxidation for metabolism, but also can carry out sulfur oxidation to a certain extent, such as cyanobacteria (also known as cyanobacteria). In recent years, it has been found that it can switch between anaerobic and aerobic photosynthesis, and these characteristics are also conducive to its application in wastewater treatment.
Chemical sulfur oxidizing bacteria are usually called colorless sulfur bacteria. They can oxidize almost all reducing sulfides to electron acceptors or even some organic sulfur compounds without light. It can be divided into four types: strict chemical inorganic autotrophic type, facultative chemical inorganic autotrophic type, chemical inorganic heterotrophic type and chemical organic heterotrophic type. Its electron acceptors can be oxygen, nitrate and nitrite nitrogen. Most autotrophic denitrifying sobs are facultative aerobic bacteria, which can utilize oxygen and nitrogen compounds as electron acceptors at the same time.