Read the full paper at: http://www.scirp.org/journal/PaperInformation.aspx?PaperID=49774 DOI: 10.4236/aim.2014.412087 Author(s) Alfred O. Ubalua ABSTRACT A mesophilic strain of Aspergillus niger isolated from cassava effluent samples produced extracellular glucoamylase in submerged culture containing 2% (w/v) soluble or sweet potato starch. On soluble starch medium the maximum glucoamylase activity in the culture filtrate was 9.40 U/mg compared to 8.24 U/mg on sweet potato starch culture filtrate. The mycelial dry weight for both media was 494 and 418 mg respectively. The maximum glucoamylase activity was obtained at a growth temperature of 40°C and pH 4.5. The implication is that the bioprocess of utilizing sweet potato starch in the culture is attractive due to its relatively cheaper availability in Nigeria, making it even more favorable when economics is considered. EWW140919GJR KEYWORDS Aspergillus niger, Sweet Potato Starch, Submerged Fermentation, Amylolytic Activity, Glucoamylase Prodcution