Production and Characterization of Gluconic Acid from Aspergillus sp Using Agro-residues as a Substrate

Abstract

Gluconic Acid is a mild organic acid which finds application in the food and pharmaceutical industry. This study, explored the production of gluconic acid through submerged fermentation using ground nut peel and corn cob as a substrates.  The soil sample from Rumuokoro dumpsite had a total fungal count of 4.5 × 104 while the sample from Rukpokwu farmland was 1.8 × 104 and the mile 3 sample had 3.4 × 104 total fungal count. Six fungal species (Aspergillus niger, Aspergillus flavus, Rhizopus oryzae, Aspergillus terreus, saccharomyces cerevisiae, Fusarium sp) were isolated and identified. Screening of the fungal species showed that Aspergillus niger demonstrated the highest gluconic acid producer. The best production conditions for gluconic acid were, substrate concentration: 30g, carbon source: corncob and groundnut peel, incubation period: 7days, pH: 6. The groundnut peel revealed proximate composition of carbohydrate content 55.4% ,moisture content 6.87% while the corn cob revealed carbohydrate content 76.18%, moisture content 15.05%. The FTIR showed the functional group present, which are the chloro C - CL symmetric stretch, carboxylic acid, methylene CH stretch, carboxylic acid methylene CH stretch, primary alcohol OH stretch and tertiary OH stretch from the study. High performance liquid chromatography (HPLC) analysis confirmed the present of gluconic acid. It is concluded that high yield of gluconic acid can be produced from groundnut peel and corn cob using A. niger.