Catalyzes the conversion of 2-hydroxyethylphosphonate into methylphosphonate in the methylphosphonate biosynthesis pathway. 2-hydroxyethylphosphonate + O2 = H(+) + hydrogencarbonate + methylphosphonate Phosphorus metabolism; phosphonate biosynthesis. The existence of the methylphosphonate biosynthesis pathway in marine microbes may explain the supersaturation of the aerobic ocean with methane. Methane is probably released following degradation of methylphosphonate produced by MpnS (PubMed:22936780). Belongs to the non-heme iron-dependent dioxygenase family. An unusual chemistry - Issue 160 of May 2014