Abstract: Six strains of Bacillus spp. were isolated and screened from the environment of aquaculture, and their protease and amylase activities were determined. Based on the determination of the activities of the two digestive enzymes, the strain ZD 02 was selected as test object, and its heat-stability was evaluated. The strain ZD 02 identified as Bacillus subtilis had higher tolerance to high temperature. Its survival rate at 90 ℃ for 10 min, 95 ℃ for 5 min, and 100 ℃ for 5 min was 93%, 93%, and 82%, respectively. At 95 ℃ and 100 ℃ for 2 min, the survival rate of the strain was less affected. Moreover, the survival rate of ZD 02 remained 94% at 102℃after adding other feed materials and manufactured into grains. Then, the ZD 02 was cultured through fermentation, and applied to the intensive culture of Litopenaeus vannamei. Three experimental groups were installed. In control group, only basal diet provided by Guangdong Evergreen Group Co., Ltd. was added; in group A, basal diet amended with 0.3% B. subtilis was supplied; in group B, 0.3% B. subtilis was applied on the basis of unchanged cost of diet description. The results showed that the survival rate of L. vannamei in experimental groups A and B was higher than that in control group (P<0.05). Compared with the control, the output of groups A and B increased by 43.0% and 36.7% (P<0.05), production value increased by 35.4% and 21.0% (P<0.05), feed conversion ratio decreased by 9.9% and 8.7%, (P<0.05), expenses including regulation substances of aquaculture, medicines, and energy expending were economized by 21.3% and 22.3%, respectively (P<0.05). No significant differences were observed in the survival rate, output, production value, feed conversion ratio, and such expenses as medicines and energy expending between groups A and B (P>0.05). The results demonstrated that the reasonable application of B. subtilis in aquaculture could promote the output and production value of L. vannamei.

Key words: Sulfur fertilization, Crops, Increase production