Short Communication Optimization of Substrate Concentration for Enhanced Citric Acid Production by Aspergillus niger M-101: Short Communication: Citric Acid Production by A. niger. Pakistan Journal of Scientific & Industrial Research. 2009;52(5):275-277. Accessed March 10, 2026. https://www.v2.pjsir.org/index.php/biological-sciences/article/view/564