the effect of ammonium chloride , sodium butyrate , sodium propionate , and the heavy metals nickel , zinc , and copper on methanogenesis by pure cultures of methanospirillum hungatei , methanosarcina barkeri , methanobacterium thermoautotrophicum , and methanobacterium formicicum at ph 6.5 was studied .
C0347988
heavy metals
C0009968
copper