Question

1. Provide two examples of anabolic pathways other that Calvin-Benson cycle used by autotrophic bacteria to build carbohydrates or their precursors. Include in your answer the sources of reducing power and chemical energy, and where these were manufactured.

Answer 1

1)Reverse tricarboxylic acid cycle -using hydrogen, sulfide, or thiosulfate as electron donors.some non-consecutive steps of the cycle can be catalyzed by minerals through photochemistry, while entire two and three-step sequences can be promoted by metal ions and iron (as reducing agent) under acidic conditions

2)Ljungdahl-Wood acetogenic pathway in Autotrophic methanogens -Methanogens are known to produce methane from substrates such as H2/CO2, acetate, formate, methanol and methylamines in a process called methanogenesis