Alternate Electron acceptors: Know what these electron acceptors will become after picking up electron. CO_2, SO_42-, Fe3+, NO_3-, NO_2-. Note these electron acceptors are not as efficient as oxygen. The final ATP yield will be lower if alternate electron acceptors are used instead of oxygen. Solution The alternate electron acceptor like CO2 ,SO42- ,FE3+,NO3-,NO2- are known to act as electron acceptors mainly under anaerobic conditions. In these organisms during electron transport chain instead of oxygen as the terminal electron acceptors the anaerobic bacteria use a wide variety of electron and play an important role in the processes of nitrification. As these molecules have a lesser redox potential than O2 they yield lesser ATP . Certain methylotropic bacteria use C1 compounds like methanol, formaldehyde ,formate and methylamines and completely oxidize them using the serine pathway. Acetogenesis is the process here in co2 and hydrogen are used to result in acetete . Similar to methanogenesis here also hydrogen is used as an electron donor while co2 is used a s an electron acceptor. De nitrification is the common process of fixing nitrogen by many nitrogenous bacteria . They use NO3-,NO2-, NO, N2 O to finally produce di nitrogen but some of the intermediate products that are formed like the N2 O contribute towards the increase n the green house gases and acid rain and global warming.many of the denitrifying bacteria also use other sources like Fe3 as electron acceptors. The de nitrification process is extensively used in sewage and waste water treatment. sulfate reduction SO42-Many gram negative bacteria uses sulphur as the terminal electron acceptor and produce hydrogen sulfide as the metabolic end product.These organisms use lactate or pyruvate as the electron donor. Some of the autotrophic sulfate reducing bacteria like Desulfotignum phosphitoxidans use phosphite HPO3- as electron donor while others like D.thiozymogenens are capable of sulphur disproprtination i.e spilliting of sulphur molecule and produce hydrogen sulpfide and sulfate. FE3+ or ferric ion acts as a terminal electron acceptor in many of the autotrophic and heterotrophic organisms this is similar tp normal electron transport chain but for the presence of ferric iron reductase as the final enzyme and the reaction results in nitrate .Some of the ferric reducing bacteria like Shewanella putrefaciens and Geobacter metallireducens can act upon toxic hydrocarbons like toluene they are used in decontaminating iron rich aquifers..

1. Alternate Electron acceptors: Know what these electron acceptors will become after picking up
electron. CO_2, SO_42-, Fe3+, NO_3-, NO_2-. Note these electron acceptors are not as efficient
as oxygen. The final ATP yield will be lower if alternate electron acceptors are used instead of
oxygen.
Solution
The alternate electron acceptor like CO2 ,SO42- ,FE3+,NO3-,NO2- are known to act as electron
acceptors mainly under anaerobic conditions. In these organisms during electron transport chain
instead of oxygen as the terminal electron acceptors the anaerobic bacteria use a wide variety of
electron and play an important role in the processes of nitrification. As these molecules have a
lesser redox potential than O2 they yield lesser ATP .
Certain methylotropic bacteria use C1 compounds like methanol, formaldehyde ,formate and
methylamines and completely oxidize them using the serine pathway.
Acetogenesis is the process here in co2 and hydrogen are used to result in acetete . Similar to
methanogenesis here also hydrogen is used as an electron donor while co2 is used a s an electron
acceptor.
De nitrification is the common process of fixing nitrogen by many nitrogenous bacteria . They
use NO3-,NO2-, NO, N2 O to finally produce di nitrogen but some of the intermediate products
that are formed like the N2 O contribute towards the increase n the green house gases and acid
rain and global warming.many of the denitrifying bacteria also use other sources like Fe3 as
electron acceptors.
The de nitrification process is extensively used in sewage and waste water treatment.
sulfate reduction SO42-Many gram negative bacteria uses sulphur as the terminal electron
acceptor and produce hydrogen sulfide as the metabolic end product.These organisms use lactate
or pyruvate as the electron donor.
Some of the autotrophic sulfate reducing bacteria like Desulfotignum phosphitoxidans use
phosphite HPO3- as electron donor while others like D.thiozymogenens are capable of sulphur
disproprtination i.e spilliting of sulphur molecule and produce hydrogen sulpfide and sulfate.
FE3+ or ferric ion acts as a terminal electron acceptor in many of the autotrophic and
heterotrophic organisms this is similar tp normal electron transport chain but for the presence of
ferric iron reductase as the final enzyme and the reaction results in nitrate .Some of the ferric
reducing bacteria like Shewanella putrefaciens and Geobacter metallireducens can act upon
toxic hydrocarbons like toluene they are used in decontaminating iron rich aquifers.