Pathway of aerobic methane biooxidation

Methane biodegradation is an exoergic process that occurs in the presence of molecular oxygen. The simplified notation of methane oxidation reaction is the following  

The process of methane oxidation is exoenergetic, and the largest portion of energy is released during the stages 3 and 4 of the process, in which formaldehyde is transformed into methanoic acid (formate), and from that into inorganic end products. 

Stoichiometrically, 1 mole of CO2 is produced as a result of oxidation of 1 mole of CH. However, in practice, a part of carbon is assimilated by bacteria, whereby a proportion of generated CO2 to consumed CH is lower than 1. The value of the proportion depends on the level of synthesis of new cell material (Hoeks, 1972) that, in turn, depends on the phase of the growth of microorganisms population. In still growing, young bacteria community 

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