In past research, when calcium carbonate was used as neutralizing agent for submerged fermentation, R. oryzae ATCC 9363 produced up to 109 g/l of lactic acid at pH 4.5 However, in the present work, as calcium carbonate was replaced by ACU-ammonia, R. oryzae ATCC 9363 produced maximum lactic acid at 92.2 2.7 g/l merely and the optimal pH was shifted to 5.25.