Applied Microbiology and Biotechnology, Vol.90, No.2, 713-719, 2011
Use of soybean vinasses as a germinant medium for a Geobacillus stearothermophilus ATCC 7953 sterilization biological indicator
A novel low-cost medium was developed from by-products and wastes from the ethanol agro-industry to replace commercial media in the production of a steam sterilization biological indicator (BI). Various recovery media were developed using soybean or sugarcane molasses and vinasse to prepare a self-contained BI. Media performance was evaluated by viability and heat resistance (D (121 A degrees C) value) according to regulatory standards. A medium produced with a soybean vinasse ratio of 1:70 (1.4%) (w/v) produced the results, with D (121 A degrees C) = 2.9 A +/- 0.5 min and Usk = 12.7 A +/- 2.1 min. The addition of 0.8% (w/v) yeast extract improved the germination of heat-damaged spores. The pH variation from 6.0 to 7.3 resulted in a gradual increase in the D (121 A degrees C) value. The absence of calcium chloride resulted in a decrease in germination, while no significant differences were observed with starch addition. Soybean vinasses may thus be used as the main component of a culture medium to substitute for commercial media in the production of self-contained biological indicators. The use of ethanol production waste in this biotechnological process realized a reliable performance, minimized the environmental impact, and decreased BI production costs while producing a high quality product.
Keywords:Biological indicator;Ethanol by-products;G. stearothermophilus;Germination medium;Soybean vinasse