TECHNOLOGY FOCUS - BIOLOGY - Preferred Method: Extraction is carried out for 0.5-2 hours for the leaves and 1-3 hours for the stems. The Stevia yeast (zymogen) is composed of Candida kyusei, Trichaspaion pencllatum, useful fungus and microbes and other fermenting microbe. Forcible fermentation is carried out in 0.5-1 volume% of Stevia yeast (zymogen) at 15-35degreesC using ultrasonic waves with a frequency of 100000 cycles/sec or higher. Re-fermentation is carried out for 15-20 days. EXAMPLE - Stevia leaves (300 g) and stems (700 g) were separately dried at 90degreesC for 26 hours, crushed and diluted. The extracts were filtered and the supernatants were concentrated. The leaf and stem concentrates were measured to have saccharinities of 25degrees and 18degrees, respectively. Separately, the sludges remaining after the filtration were mixed and fermented at room temperature for 6 months to culture zymogen.    To each of the leaf concentrate and stem concentrate, 2 volume% of the zymogen was added and then forcibly fermented at 30degreesC for 24 hours under ultrasonic waves. The fermented concentrates were tested for toxicity and an examination was made of their odors with the senses of smell and taste. Stevia concentrates were initially bitter to the sense of taste and gave off a bad smell, but the bad smell was significantly alleviated after the ultrasonication.    The fermented leaf and stem solution were separately fermented at room temperature for 4 months and the resulting fermented leaf concentrate was mixed at volume ratio of 4:6 with the fermented stem concentrate and the mixture was subjected to re-fermentation in an ultrasonic mixer to produce 500 g of a dioxin decomposer. The dioxin decomposer was not offensive to the sense of smell. The dioxin decomposer was diluted, mixed with 1 g of burn-outs at room temperature by stirring.    Dioxin concentrations of the burn-outs before and after the treatment with the dioxin decomposer were measured to determine the decomposition effect of the decomposer. The results showed that the dioxin concentrations were reduced by 46% by mixing the dioxin decomposer with dioxins or dioxin-containing materials at room temperature. Also, the decomposer had excellent decomposition effects on 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 2,3,7,8-TCDF, known as the most toxic among dioxin species.