Citric acid production and citrate synthase genes in distinct strains of Aspergillus niger

Abstract

Citric acid is an important organic acid, multifunctional with a wide array of uses. The objectives of this study were the isolation and selection strains of the genus Aspergillus, investigating the solubilization of phosphate of these isolates, verifying the expression rate of genes involved in the identification of isolates, and efficiency of citrate synthase in the citric acid production. To verify the mechanisms of the microorganisms in solubilizing phosphate into the medium in the citric acid production, Araxá rock phosphate was utilized. Further, citric acid was evaluated in two culture media, namely BD and SA. The amplification by the polymerase chain reaction was done by using primer ITS region and citrate synthase (P1/P2). The isolates of Aspergillus niger were efficient to solubilize phosphate. The isolate A. niger 00118 stood out in the solubilization with an increase as high as five times the amount of soluble phosphorus when compared with the control treatment. The results of citric acid production highlighted better influence conditions of the culture medium Sabouraud (SA) on its production. The P1/P2 primer was sensitive in distinguishing the isolates A. niger 00116, A. niger 00104, A. niger 00098 and A. niger 00118 in the analysis of citrate synthase enzyme genes.