▁in ▁waste ▁water ▁treatment ▁since ▁the ▁mid - 1 9 8 0 s . ▁ ▁Research ers ▁have ▁sought ▁ways ▁to ▁use ▁it ▁as ▁an ▁alternative ▁power ▁source . ▁M eth anos arc ina ▁stra ins ▁were ▁grown ▁in ▁single - cell ▁morph ology ▁( S ow ers ▁et ▁al . ▁ 1 9 9 3 ) ▁at ▁ 3 5   ° C ▁in ▁H S ▁bro th ▁medium ▁containing ▁ 1 2 5 ▁m M ▁m eth an ol ▁plus ▁ 4 0 ▁m M ▁sod ium ▁ac et ate ▁( HS - MA ▁medium ). ▁ ▁Over view ▁M eth anos arc ina ▁may ▁be ▁the ▁only ▁known ▁an a er ob ic ▁m eth an og ens ▁that ▁produce ▁m eth ane ▁using ▁all ▁three ▁known ▁met abol ic ▁path ways ▁for ▁m eth an ogen esis . ▁M eth an ogen esis ▁is ▁critical ▁to ▁the ▁waste - tre at ment ▁industry ▁and ▁bi olog ically ▁produced ▁m eth ane ▁also ▁represents ▁an ▁important ▁alternative ▁fuel ▁source . ▁Most ▁m eth an og ens ▁make ▁m eth ane ▁from ▁carbon ▁dio x ide ▁and ▁hydro gen ▁gas . ▁ ▁O thers ▁util ize ▁ac et ate ▁in ▁the ▁ac et oc last ic ▁path way . ▁In ▁addition ▁to ▁these ▁two ▁path ways , ▁species ▁of ▁M eth anos arc ina ▁can ▁also ▁met abol ize ▁m eth yl ated ▁one - car bon ▁comp ounds ▁through ▁m eth yl ot roph ic ▁m eth an ogen esis