Toxicity Assessment and Application as the Soil Fertilization of Bean Curd Refuse Decomposed by Bacillus sp. HR6

Abstract

The acute virulence of bean curd refuse decomposed by Bacillus sp. HR6 was examined by using Oryzias latipes and mice to reutilize the compost as the soil fertilization. After 48 hrs. of incubation, the cells (totally 4.0×10¹²) had no effects on the viability of 10 Oryzias latipes in 4l of water tank. The same was true as for the acute virulence of compost toward mice. Fifty mg of compost containing Bacillus sp. HR6 were given per 10g of mouse weight, and the change of weight and the conditions of internal organs were examined after 14 days. As a result, no change was observed in comparison with that of control. The growth of Komatsuna plant was repressed by the addition of compost in the range of 100 to 400 mg nitrogen content to the soil comparing with that of organic fertilizer commercially available. The soil with both 12g of compost and leaf mold, however, promoted the growth of Komatsuna plant. These results indicate that the compost obtained was secure for the living things and that it is useful as soil fertilization.