拮抗菌B501的鉴定及其对采后冬枣黑斑病的抑制效果

Identification of Bacterial Strain B501 and Its Biocontrol Activity against Black Spot on Jujube Fruits

细菌菌株B501分离自冬枣表面,根据其理化性质和16S rDNA序列的进化树分析,鉴定为成团泛菌(Pantoea agglomerans)。菌株B501对链格孢引起的冬枣黑斑病有明显的防治作用,其防病效果与使用浓度成正比,浓度为1×107cfu/ml时对冬枣黑斑病的抑制率达80%以上。该菌在冬枣伤口上有较强的定殖能力,添加2%CaCl2可提高其在伤口处的菌群数量;而50μg/ml浓度的扑海因则对伤口处拮抗细菌数量有一定的抑制。菌株B501与链格孢在PDA平板对峙试验中不产生抑菌圈,其活菌液处理冬枣的防病效果较好,而培养滤液和灭菌培养液则无防病效果,其防病机制可能与空间和营养竞争有关。

Strain B501 was isolated from surface of jujube fruit and showed antagonistic activity against the black spot disease caused by Alternaria alternata on jujube fruits. This bacterium was identified as Pantoea agglomerans according to the physiological, biochemical properties and the phylogenetic analysis of its 16S rDNA sequence. B501 could noticeably reduce the incidence of the black spot when applied on wounded fruits at a relatively low concentration of 1×10^7 cfu/ml, and there was a significantly positive correlation between the concentrations of strain B501 and its antagonistic activity. Strain B501 colonized with a large population in wounds on jujube fruits. The presence of calcium chloride at 2% concentration significantly increased the population of B501, whereas adding 50 μg/ml of iprodione reduced the colonizing ability of this bacterium. The preliminary action model study showed that P. agglomerans B501 eould not inhibit the myeelial growth of A. alternata on medium, and the eells alive rather than autoelaved euhure and eell-free cultural filtrate provided the proteetion against A. alternate.