Journal of Advances in Microbiology

Citric acid is one of the most commonly used and easily available multifunctional organic acids. This is widely used in different industrial applications. Citric acid is 2hydroxyl 1,2,3 propanetricarboxylic acid. It is present in many fruits and vegetables. Citric acid is usually found in lemon. The global demand for Citric acid is about 6.08x10⁵per year its uses are increasing day by day. Aspergillus niger and Aspergillus flavus organisms are used for citric acid production. In this present study citric acid production from the different waste substrates such as Banana peels, Coconut husk, and Rice straw were carried out using Aspergillus niger and Aspergillus flavus isolated from soil sample. Characterization and identification were done with the help of microscopic examination based on lactophenol cotton blue staining. Aspergillus niger and Aspergillus flavus are appeared as branched hypae with conidial spore. The production of citric acid was performed by solid state fermentation and estimated on the different fermentation days, different pH and different concentration of substrate. We observed that high level of citric acid production was on 9^th day of fermentation as compared to others days of fermentation.