黑曲霉菌株Y-1对盾壳霉寄生核盘菌菌核的影响

Effect of Aspergillus niger strain Y-1 on infection of Sclerotinia sclerotiorum sclerotia by Coniothyrium minitans

本文旨在评估黑曲霉(Aspergillus niger)对核盘菌菌核围细菌的拮抗作用,探讨将黑曲霉与生防菌盾壳霉(Coniothyrium minitans)混用,以提高盾壳霉对核盘菌菌核的寄生效果。平板拮抗结果显示,黑曲霉发酵液对核盘菌菌核围优势种群假单胞菌属、芽孢杆菌属细菌和其他种群短杆菌属、节杆菌属细菌均具有较强抑菌活性,产生大于2.0 cm的抑菌圈。高效液相色谱检测结果表明,黑曲霉摇培6 d时,发酵液中草酸含量为40.7 mmol·L-1。草酸(40 mmol·L-1)能显著抑制菌核围细菌生长,其抑菌活性与黑曲霉发酵液相当。将发酵液pH值调节为pH 7时抑菌活性消失,说明黑曲霉分泌草酸营造的酸性环境是其抑制细菌的主要原因。低浓度(1%~5%)黑曲霉发酵液对盾壳霉孢子萌发无显著抑制作用。室内无菌砂皿寄生菌核结果表明,黑曲霉对核盘菌菌核的重寄生能力较弱,黑曲霉与盾壳霉混用对菌核的寄生效果与盾壳霉单独处理无明显差异。田间盆栽试验结果显示,黑曲霉与盾壳霉混用对菌核萌发子囊盘的抑制效果(83.78%)显著高于盾壳霉单独处理(69.37%)。说明黑曲霉与盾壳霉混用能提高对菌核的寄生效果。

The objective of this study is to evaluate the inhibitory effect of Aspergillus niger Y-1 on bacteria colonized in sclerosphere of Sclerotinia sclerotiorum,and to investigate the co-infection activity of Y-1 and another biocontrol agent Conithyrium minitans on sclerotia.The results showed that the culture filtrate of Y-1 exhibited obvious antibacterial activity in the plate assay against the representative bacteria in sclerosphere(including species in genera Pseudomonas,Bacillus,Brevibacterium and Archrobacter),and the diameter of inhibitory zone was greater than 2.0 cm.HPLC analysis showed that the yield of oxalic acid in Y-1 filtrate cultured for 6 days was up to 40.7 mmol·L^(-1),and its antibacterial activity was comparable to that of 40 mmol·L^(-1)pure oxalic acid solution.When the pH value was adjusted to 7,the antibacterial activity of the filtrate disappeared,indicating that the oxalic acid secreted by A.niger was the major antibacterial compound.The dilution of A.niger filtrate at low concentrations(1%~5%)had no significant influence on conidial germination of C.minitans.A.niger showed a weak parasitic activity on sclerotia in the test on sand,and the parasitic effect of mixed A.niger and C.minitans was not significantly different from that of C.minitans alone.The pot experiment showed that the biocontrol efficiency of mixture A.niger and C.minitans(83.78%)on reducing the number of apothecia produced by S.sclerotiorum was significantly higher than that of C.minitans alone(69.37%).These results suggest that the combined use of A.niger and C.minitans could improve the parasitism effect on the sclerotia of S.sclerotiorum.