枯草芽孢杆菌与钾联用对黑腐皮菌的抑制作用

Inhibitory Effect of Bacillus subtilis Combined with Potassium against Valsa mali

为明确枯草芽孢杆菌(Bacillus subtilis)与钾联用后对黑腐皮菌(Valsa mali)的抑制作用,采用比浊法分别测定了含不同浓度KH_2PO_4,KCl和K_2SO_4的枯草芽孢杆菌发酵液OD600,评估钾对菌株LF17生长的影响;通过固体平板扩散法-打孔法测定了枯草芽孢杆菌与钾联用后对黑腐皮菌的抑制作用。结果表明,发酵液中加入KH_2PO_4和KCl后,菌株LF17活菌数呈上升趋势,其增幅范围分别为2.2×108～1.5×109,9.0×107～1.4×108 cfu/m L;加入K_2SO_4后,活菌数呈现降低趋势,质量浓度为10 mg/m L时,活菌数量降低了1.72×109 cfu/m L。KH_2PO_4和KCl质量浓度分别为15,2 mg/m L时,培养10 d后,对黑腐皮菌的抑菌率达最高,分别为96.33%和95.56%。研究发现,与联用KCl和K2SO4相比,联用KH_2PO_4后发酵液的活菌数显著增加,其抑菌率和抑菌稳定性显著提高,表现为协同增效。

To clarify the inhibitory effect of Bacillus subtilis combined with potassium on Valsa mali, the OD600 value of Bacillus subtilis fermentation broth containing KH2PO4, KCl and K2SO4 was measured by turbidimetry, then evaluated the effect of potassium on the growth of strain LF17. The inhibitory effect of Bacillus subtilis and potassium on Valsa mali was tested by solid plate diffusion method. The result showed that the living bacteria number of Bacillus subtilis presented an upward trend after different concentrations of KH2PO4 and KCl were added into the fermentation broth of Bacillus subtilis. The growth ranges were 2.2×10^8-1.5×10^9 cfu/mL and 9.0×10^7-1.4×10^8 cfu/mL. The living bacteria number showed a decreasing trend when added K2SO4 into the fermentation broth. The living bacteria number decreased by 1.72×10^9 cfu/mL with 10 mg/mL concentration of K2SO4. The inhibitory rate reached 96.33% and 95.56% after 10 d while the concentration of KH2PO4 and KCl was 15, 2 mg/mL, respectively. The living bacteria number increased significantly after adding KH2PO4 into the fermentation broth compared to the combination of KCl and K2SO4. The inhibitory rate and stability were significantly improved, and the results showed synergistic interaction.