Question

A bacterium isolated from sewage sludge was recently found to be capable of anoxygenic photosynthesis using nitrite as the electron donor, converting it to nitrate. Compare this form of nitrification to that which is well characterized. By removing nitrite from the environment, what other processes within the nitrogen cycle might this bacterium be influencing?

Answer 1

there are two main types of photosynthesis

oxygenic .that generates oxygen and anoxygenic ,that doesnot generate oxygen

in oxygenic one light energy absorbed by psii exciting p680 and make it electrone donor ,water split to generate electrones used to reduce p680 .protons from water create proton motive force and o2 released .electrones travel through a series of electron carriers and reduce p700 in psi .the last step is the reduction of nadp to nadph

in anoxygenic many steps are same as oxygenic ,like excitation of photosynthetic pigment

but oxygen is not released because p680 of psii is not present .water is too electroposiive to act as electrone donor the reaction centre of purple bacteria is p870 ,it varies according to species electrones cycle back to p870 so atp generated by cyclic phosphorelation . therefore no nadph made .without nadh cells have to come up with anotherway of generating the reducing power necessary to drive calvincycle or carbon fixation

this denitryfying bacteria help to remove nitrites by denitrification by reducing it also it decomposes nitrogen containig compounds by a process of deamination .and eukaryotes assimilate this nitrogen in the form of nitrate and ammonia .when the plants and animals die the nitrogen compounds reenter the soil again decomposed and go through nitrification process