The Impact Of Culture Conditions On The Production Of Bacillus Subtilis B68 And It's Biological Control Agent Were Initially Researched

The antagonistic strain Bacillus subtilis B68 was screened from banana plantation in Danzhou,Hainan province.It had a strong antagonism to the pathogen of banana crown rot. In order to manufacture the biological control agent of B68, the nutritional conditions of spore formation rate and quantity of Bacillus subtilis B68 were studied, and then, we has studied the B68 strain to the banana on the commonly used agricultural chemicals antibiotic nature, at last, we manufactured the biological control agent of B68. The results of this paper as the following:1. The optimal conditions on the production of Bacillus subtilis B68: the optimal medium composition for spore formation was as follows glucose 10g,soya flour 10g,NaCl 5g, MnSO₄·H₂O 0.6g,H2O 1000ml,optimal initial pH was 7.0 and appropriate medium volume was 100ml in 250ml flask. The spore number can reach 1.60×10¹⁴CFU/ml, with the highest spore formation of 88.92% at 28℃,150r/min for 72h.2. The B68 strain were settled down and reproduced in banana, the results showed that they can easy settled down and reproduced in banana, and the quantity of Bacillus subtilis B68 were variational, the flood tide appear in after 5 days, and then the quantity of Bacillus subtilis B68 were down after 7 days.3. Studied of the commonly used agricultural chemicals antibiotic of the B68 strain nature on the banana, the results showed that in tests in 10 kind of commonly used pesticide, Yunchu and Duojunling not only have not suppressed the bacterial quantity and spore formation quantity of Bacillus subtilis B68, instead promotes its output increase., heteropolarly compares the difference with the comparison to be remarkable, Other 8 kind of commonly used agricultural pesticide have the suppression influence to the bacterial quantity and spore formation quantity of Bacillus subtilis B68, but the analysis in SARS demonstration difference is not remarkable ,is in the identical level. 4. Initially studied on the AS and WP of Bacillus subtilis B68, the AS of B68 relative preventing and controlling effect of banana is 68.42%, the spore existent rate is 92.84% after 7 months;the WP of B68 researched through 6 kind of the quantity adsorption of carriers , synthesis consideration and so on shelf life, cost. Had finally determined saws the sawdust to take the adsorption carrier, its quantity adsorption is 2.4L/kg, deposits 5 months B68 survival percentage is 64.5%.