MORPHOLOGY AND CITRIC-ACID PRODUCTION OF ASPERGILLUS-NIGER-PM-1

Aspergillus niger PM I was grown in a tubular loop and a stirred tank bioreactor. Batch fermentations were performed under various agitation conditions and pH. Citric acid, oxalic acid, extracellular polysaccha rides and proteins were assayed. The following morphological parameter s were measured: mean perimeter of clumps, mean perimeter of the centr al core of clumps, mean length of filaments and mean diameter:of filam ents. Citric acid production and morphology in both reactors were depe ndent,on agitation intensity and pH. The length of the filaments was s hown to be the only parameter that could be related to citric acid pro duction in both reactors :the shorter the filaments the more citric ac id was produced. However, for the same amount of citric acid produced the morphology of the organism grown in the stirred tank differed cons iderably from that grown in the loop reactor.