the surface of the fermentation medium to the top of the vessel to prevent the dissolution of atmospheric oxygen into the fermentation medium inert gas is not required during the fermentation of these two strains because strain 1218 regularly produces 1 5 moles of carbon dioxide for each mole of dissacharide and 0 75 moles for each mole of monosaccharide fermented because strain 1218 v criceti is an obligate anaerobe care must be taken not to oxidize the fermentation medium by spraying or bubbling air or oxygen in this experiment the two strains cls917 and 1218 were cultivated in three liters of a medium containing lactose 2 supplied as either whole whey or ultrafiltered whey permeate yeast extract 1 0 and 60 millimolar calcium carbonate the conditions of the fermentation included a temperature of 38 u00b0 c maintenance of ph between 5 5 and 6 0 by the automatic or manual addition of ph control agent and continuous stirred agitation in a cell stir jar bellco glass co at a speed of 200 revolutions per minute aliquots were removed at the beginning of the fermentation and at 4 8 12 24 and 48 hours during the fermentation these samples were analyzed for acetic acet propionic prop and lactic lact acids using the methodology previously described concentrations of these metabolic acid products from the 24 hour samples in which either a reducing agent inert gas or neither were used are presented in table 4 it is evident from these data that standard fermentation preparations are sufficient under.