Role of formate hydrogen lyase complex in hydrogen production in facultative anaerobes

•The role of formate lyase enzyme complex in H2 production.•Distribution of formate lyase enzyme complex in microbial community.•Molecular and biochemical aspects of formate lyase pathway.•Influence of physicochemical parameters in hydrogen production.

Facultative anaerobes play important roles in H2 production by biological routes. In the present study, a comprehensive insight on the importance of formate lyase in H2 production by facultative microorganisms has been focused. Structural details of formate hydrogen lyase reveal the involvement of two enzymes, formate dehydrogenase H (FdhH) and hydrogenase (Hyd) along with electron carriers. The monocistronic fdhF gene codes for the functional formate dehydrogenase H. Functionality of these complexes are dependent on maturation system governed by FDH-D and FDH-E. The overall transcription of FHL complex is governed by protein encoded by fhlA gene. Under anaerobic condition, the pyruvate gets cleave into acetyl-CoA and formate by pyruvate-formate-lyase (PFL). The transporter proteins FocA and FocB helps in transporting formate. During dark fermentation, the physico–chemical parameters such as pH, HRTs, partial pressure play a crucial role in influencing formate degradation to molecular H2.

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