Microbiology Research Journal International

Enzymes have been used in the production of consumables such as cheese, wine, beer, and vinegar, as well as in the development of products such as leather and linen. The discovery of fermentation processes over the latter part of the previous century, explicitly aimed at the production of enzymes utilising selective growth strains. Multiple microbial enzymes are well-identified catalysts for the synthesis of several products from a diverse range of substrates under regulated conditions. The need for large-scale production of enzymes from agro-residues for industrial application in Nigeria has become a source of worry to the enzyme-based industry. The aim of the study was to produce glucoamylase from fungi using agro-residue substrate. Fungi were isolated from soil and screened for glucoamylase production. Yam and potato peels were obtained and analysed for their composition. The peels were fermented using fungi positive for glucoamylase production, and process parameters were monitored. The data obtained from the compositional analysis of the agro residues were analysed using the One-way ANOVA to ascertain if any significant difference existed in the composition. The data obtained from the time-course study of glucoamylase activity at p-value <0.05 was ascertained. The result showed that the fungal population of the soil ranged from 1.0 x10⁴CFU/g to 2.4 x10⁴CFU/g. The isolated fungi were identified as Fusarium sp, Aspergillus niger, Rhizopus sp, Aspergillus sp and Penicillium sp. Aspergillus niger Had the highest potential for glucoamylase production on starch agar. The carbohydrate content of the yam and potato peels was 73.16 and 76.51%, respectively; protein content was 0.25 and 0.23%, respectively; and fibre content was 1.42 and 1.74%, respectively. The maximum yield of glucoamylase was recorded in Apergillus niger 37.13IU/ml while Aspergillus sp had glucoamylase yield of 26.12 IU/ml. At pH 6.0, a glucoamylase concentration of 24.18 IU/ml was obtained, and using a fungal inoculum size of 3 ml resulted in a glucoamylase concentration of 45.08 IU/ml. The carbon source (combination of yam and potato peel, 5g each) and nitrogen source, urea, had glucoamylase production of 32.17IU/ml and 58.36IU/ml, respectively. It is concluded that high yield of glucoamylase can be produced from yam and potato peels using A. niger.