产酶溶杆菌LE16对采后柑橘青霉绿霉病的防治作用

Control Effect of Lysobacter enzymogenes LE16 on Rot Disease in Post-harvest Citrus Fruit Caused by Penicillium digitatum and P.italicum

为了防治采后柑橘青霉(Penicillium italicum)和绿霉(P.digitatum)引起的果实腐烂,以自主分离的产酶溶杆菌新株Lysobacter enzymogenes LE16为对象,研究其自溶发酵液和所产生的挥发性物质对青霉和绿霉菌丝生长及孢子萌发的抑制作用;利用液相色谱—质谱联用(Liquid Chromatograph Mass Spectrometer,LC-MS)检测分析LE16发酵液的抗菌成分;通过果实创伤接种和商品化保鲜试验,明确菌株LE16对青霉和绿霉的防治效果。结果显示:在纯培养试验中,LE16显著抑制青霉和绿霉菌丝生长,其发酵液固形物和其产生的挥发性物质最大抑制率为100%和77.52%~91.11%;其发酵液固形物使病菌孢子的萌发率降低96%以上,使病菌菌丝空泡化和扭曲畸形。经80、90和100℃高温加热30 min后,对青霉和绿霉菌丝生长的抑制效果与常温处理(28℃)无显著差异。LC-MS分析结果表明,菌株LE16可产生大量次级代谢产物,其中包括肉桂醛、肉桂酸、月桂酸和γ-丁内酯等抗菌化合物。在创伤接种青霉试验中,LE16发酵液处理的柑橘果皮中超氧化物歧化酶和过氧化氢酶活性提高,丙二醛含量和细胞膜透性降低;各处理的发病率和病情指数:对照>LE16发酵液>咪鲜胺>50%LE16发酵液+50%咪鲜胺,防治效果则相反。在商品化贮藏保鲜试验中,LE16发酵液处理对柑橘果实品质无不良影响;贮藏15 d时LE16发酵液、咪鲜胺和50%LE16发酵液+50%咪鲜胺的防治效果依次为50.00%、83.33%和75.93%,说明柑橘储藏过程中,LE16发酵液显著降低烂果率,在获得同样防治效果的情况下,可大幅度减少农药施用量。综上可知,LE16分泌的代谢产物抑制青霉和绿霉菌丝生长和孢子萌发,防止柑橘果实腐烂,可减少化学药剂咪鲜胺用量,对果实品质无不良影响,在柑橘采后保鲜方面有潜在的应用价值。

In order to prevent citrus fruit decay caused by Penicillium italicum and P.digitatum in postharvest,a self-screened strain of Lysobacter enzymogenes LE16 applied to test,and the inhibitory effects of self-digestive fermentation liquid and volatile organic compounds(VOCs)of LE16 on the mycelium growth and spore germination of P.italicum and P.digitatum were studied.In addition,the antibacterial components of self-digestive fermentation liquid were analyzed by liquid chromatography-mass spectrometry(LC-MS).Furthermore,the control effect of strain LE16 on P.italicum and P.digitatum was determined by the fruit trauma inoculation and commercial simulation storage.Results from the pure culture experiment showed that both self-digestive fermentation liquid and volatile organic compounds significantly inhibited the mycelium growth of P.digitatum and P.italicum by 100% and 77.52%-91.11%,respectively.The self-digestive fermentation liquid also reduced the spore germination rate by>96%,and resulted in the mycelial vacuolation and distortion.No significantly differences on the mycelium growth of P.digitatum and P.italicum were observed for the inhibition effect of self-digestive fermentation liquid that was treated under 80,90 and 100℃ for 30 minutes.The result of self-digestive fermentation liquid through LC-MS analysis showed that LE16 produced a number of secondary metabolites including cinnamaldehyde,cinnamic acid,dodecanoic acid andγ-butyrolactone and other antibacterial chemicals.In the fruit trauma inoculation test with P.italicum,the activities of superoxide dismutase and catalase in citrus peel were increased,but the content of malondialdehyde and cell membrane permeability was decreased.Significant decreases in the disease incidence and disease index of citrus fruit were ranked as the control>LE16>prochloraz>50% LE16+50% prochloraz,while the control efficacy showed an opposite trend.There were no significant changes in the quality of citrus fruits under the self-digestive fermentation liquid treatment during the commercial simulation storage.The control effects were 50.00% under LE16,83.33% under prochloraz and 75.93% under 50% LE16+50% prochloraz after 15 days storage,respectively.The results demonstrate that self-digestive fermentation liquid of LE16 as a promising biological preservative for the postharvest fruit preservation,can decrease the mycelium growth of P.digitatum and P.italicum and related fruit disease incidence,and the self-digestive fermentation liquid application will partly reduce the use of chemical fungicides without changes in the quality of citrus fruits.