the possible reason to explain this result is lack of sufficient nitrogen source, an important nutrient component for C. growth and acetic acid formation.
the co-culture acetic acid fermentation was improved by using corn meal hydrolyzate, and the reactor productivity increased to 0.935 g/(1 h), close to the one reported before, 1.23 g/(1 h), when whey permeate was supplemented with corn steep liquor.
the improvement was attributed to the direct utilization of the nutrient components (Protein and amino acid) existing in the corn meal hydrolyzate.
since no addition nitrogen sources were necessary to achieve a high yield and production rate, this fermentation process can be used economically for acetic acid production from the relatively abundant and inexpensive corn meal.