枸杞内生嗜线虫镰刀菌对灵武长枣采后致腐真菌的抑制作用

Antibacterial effect of Fusarium nematophilum of Lycium barbarum on rot-causing fungi in oostharvest Ziziphus jujube cv.Lingwuchangzao

【目的】研究枸杞内生嗜线虫镰刀菌(Fusarium nematophilum)NQ8GⅡ4对灵武长枣致腐真菌的抑制作用和保鲜效果,为灵武长枣采后保鲜提供参考。【方法】以灵武长枣采后优势致腐真菌交链格孢(Alternaria alternata)和灰葡萄孢(Botrytis cinerea)为靶标菌,采用皿内对峙试验,设同时接种NQ8GⅡ4和靶标菌、接种NQ8GⅡ44 d后再接种靶标菌和接种靶标菌4 d后再接种NQ8GⅡ43个处理,测定NQ8GⅡ4的抑菌率;采用盖玻片对峙法培养NQ8GⅡ4和靶标菌,显微观察NQ8GⅡ4对靶标菌的拮抗作用。制备NQ8GⅡ4培养液,检测其对靶标菌丝生长(培养液体积分数为10%,15%,20%,25%,30%和40%)和孢子萌发(培养液体积分数10%,20%,30%,40%和50%)的抑制作用。采用皿内对峙法测定NQ8GⅡ4对米根霉(Rhizopus oryzae)、出芽短梗霉(Aureobasidium pullulans)和球派伦霉(Peyronellaea glomerata)的抑菌广谱性。采用平板对扣法测定NQ8GⅡ4挥发物质对靶标菌丝生长的抑制作用。将灵武长枣用NQ8GⅡ4培养液体积分数分别为10%,20%,30%,40%和50%的液体浸泡1 min后晾干,15℃冷藏,以无菌水浸泡处理为对照,每隔5 d观察腐烂情况并统计腐烂率,分析NQ8GⅡ4培养液对灵武长枣的保鲜作用。【结果】接种NQ8GⅡ44 d后再接种靶标菌处理的抑菌效果显著高于其他2个处理,该处理对交链格孢和灰葡萄孢的抑菌率分别达71.25%和68.75%。光学显微观察发现,菌株NQ8GⅡ4可使病原真菌菌丝出现畸形、干瘪和崩解等现象。菌株NQ8GⅡ4培养液对交链格孢和灰葡萄孢的菌丝抑制率分别为71.25%和62.00%;菌株NQ8GⅡ4培养液体积分数为50%时,对交链格孢和灰葡萄孢的分生孢子萌发抑制率分别达92.81%和88.72%。NQ8GⅡ4挥发物质对交链格孢和灰葡萄孢的抑菌率分别达94.34%和95.95%。菌株NQ8GⅡ4对出芽短梗霉、球派伦霉和米根霉抑制率分别达87.91%,75.42%和30.95%。在15℃贮藏条件下,体积分数20%的NQ8GⅡ4培养液处理30 d后,灵武长枣的腐烂率较对照处理下降了77.09%,货架期延长了15~30 d。【结论】枸杞内生嗜线虫镰刀菌NQ8GⅡ4是极具应用前景的果蔬保鲜剂出发菌种。

【Objective】This study clarified the bacteriostasis and preservation effect of the antagonistic Fusarium nematophilum strain NQ8GⅡ4 on pathogenic fungus of Ziziphus jujube cv.Lingwuchangzao to provide reference for its postharvest preservation.【Method】With the dominant decay-causing fungi Alternaria alternata and Botrytis cinerea after collection of Ziziphus jujube cv.Lingwu changzao as the target pathogenic fungi.The antibacterial rate of NQ8GⅡ4 was determined by in-dish confrontation test.Three treatments were set up:inoculation with NQ8GⅡ4 and target fungi at the same time,inoculation with NQ8GⅡ4 for 4 d followed by inoculation with target fungi,and inoculation with NQ8GⅡ4 for 4 d followed by inoculation with target fungi;the antagonistic effect of NQ8GⅡ4 on the target fungi was observed microscopically by culturing NQ8GⅡ4 and the target fungi using the coverslip standoff method.NQ8GⅡ4 culture filtrate was prepared,and its inhibitory effect on the growth of target mycelium(The volume ratios of the culture medium were 10%,15%,20%,25%,30%and 40%,respectively)and spore germination was tested(The volume ratios of the culture medium were 10%,20%,30%,40%and 50%,respectively).The broad-spectrum antibacterial activity of NQ8GⅡ4 against Rhizopus oryzae,Aureobasidium pullulans and Peyronellaea glomerata was determined by in-dish confrontation method.The inhibition of NQ8GⅡ4 volatile substances on the growth of target mycelia was determined by the plate-to-button method.To analyze the preservation effect of NQ8GⅡ4 culture solution on Ziziphus jujube cv.Lingwu changzao,we used the method of soaking Ziziphus jujube cv.Lingwuchangzao with NQ8GⅡ4 culture filtrate solution content of 10%,20%,30%,40%and 50%by volume for 1 min and then dried,refrigerated at 15℃,with sterile water soaking treatment as the control,and observed the decay and counted the decay rate every 5 d.【Result】The antibacterial effect of inoculating strain NQ8GⅡ44 days before inoculating pathogenic fungi was significantly higher than that of simultaneously inoculating strain NQ8GⅡ4 and pathogenic bacteria.The bacteriostatic effect of NQ8GⅡ4 against A.alternata and B.cinerea were 71.25%and 68.75%,respectively.Optical microscopic observation showed that NQ8GⅡ4 could cause malformation,disintegration and branching increase to the mycelia of spoilage fungi.The culture filtrate of NQ8GⅡ4 effectively inhibited the growth of A.alternata and B.cinerea hyphae with inhibition rates of 71.25%and 62.00%,respectively;When the culture filtrate fraction of strain NQ8GⅡ4 was 50%,the conidial germination inhibition rates of A.alternata and B.cinerea were 92.81%and 88.72%,respectively.The inhibition rate of volatile substances of NQ8GⅡ4 to pathogenic fungi A.alternata and B.cinerea reached 94.34%and 95.95%respectively.The inhibition rates of strain NQ8GⅡ4 against A.pullulans,P.glomerata and R.oryzae were 87.91%,75.42%and 30.95%,respectively.Compared with control,NQ8GⅡ4 strain culture filtrate at 20%volume fraction had the best preservation effect with decay rate reduced by 77.09%and shelf life extended by 15-30 days at 15℃.【Conclusion】Fusarium nematophilum NQ8GⅡ4 is a promising strain for fruits and vegetables preservation.