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In general, photosynthesis in cyanobacteria uses water as an electron donor and produces oxygen as a byproduct, though some may also use hydrogen sulfide [83] a process which occurs among other photosynthetic bacteria such as the purple sulfur bacteria. Carbon dioxide is reduced to form carbohydrates via the Calvin cycle. [84]
Purple bacteria or purple photosynthetic bacteria are Gram-negative proteobacteria that are phototrophic, capable of producing their own food via photosynthesis. [1] They are pigmented with bacteriochlorophyll a or b , together with various carotenoids , which give them colours ranging between purple, red, brown, and orange.
The purple sulfur bacteria (PSB) are part of a group of Pseudomonadota capable of photosynthesis, collectively referred to as purple bacteria. They are anaerobic or microaerophilic , and are often found in stratified water environments including hot springs , stagnant water bodies, as well as microbial mats in intertidal zones.
In general outline, photosynthesis is the opposite of cellular respiration: while photosynthesis is a process of reduction of carbon dioxide to carbohydrates, cellular respiration is the oxidation of carbohydrates or other nutrients to carbon dioxide. Nutrients used in cellular respiration include carbohydrates, amino acids and fatty acids.
As cyanobacteria are bacteria that use light to fuel their energy-producing photosynthetic machinery they depend on perceiving light in order to optimize their response and to avoid harmful light that could result in the formation of reactive oxygen species and subsequently in their death. [28]
The general lack of internal membranes in bacteria means these reactions, such as electron transport, occur across the cell membrane between the cytoplasm and the outside of the cell or periplasm. [65] However, in many photosynthetic bacteria, the plasma membrane is highly folded and fills most of the cell with layers of light-gathering ...
Oxygenic photosynthesis can be performed by plants and cyanobacteria; cyanobacteria are believed to be the progenitors of the photosystem-containing chloroplasts of eukaryotes. Photosynthetic bacteria that cannot produce oxygen have only one photosystem, which is similar to either PSI or PSII.
In addition to demarcating taxonomic ranks, CSIs may play a role in the unique characteristics of members within the clade: In particular, a four-amino-acid insert in the protein pyruvate flavodoxin/ferredoxin oxidoreductase, a protein which plays important roles in photosynthetic organisms, has been found exclusively among all members in the ...