Abstract: To screen for lactic acid bacteria with antagonistic activity against Alternaria alternata，the causal agent of leaf mold in Zanthoxylum，and to investigate the antifungal mechanism，lactic acid bacteria were isolated from the milky white exudate naturally secreted by healthy Zanthoxylum trees in the Longnan City of Gansu Province.With A.alternata as the indicator pathogen，antagonistic strains were screened.The effective strain was identified by morphological observation and molecular phylogenetic analysis，and its antifungal activity，metabolites，and biological characteristics were systematically evaluated.The results showed that the antagonistic strain HJ⁃L exhibited an inhibition rate of 83.2% against A.alternata.Strain HJ⁃L was identified as Leuconostoc suionicum.The ethyl acetate extract of its fermentation broth showed a minimum inhibitory concentration（MIC） of 10.00 mg/mL and a minimum fungicidal concentration（MFC） of 10.00 mg/mL against the pathogen，and induced abnormal mycelial morphology.Strain HJ⁃L also exhibited broad⁃spectrum antifungal activity against five other plant pathogenic fungi，namely Fusarium solani，F.oxysporum，F.proliferatum,F.circinatum，and Colletotrichum fioriniae，with inhibition rates ranging from 62.5% to 88.7%.Metabolomic analysis revealed seven potential antifungal compounds derived from the fermentation extract of strain HJ⁃L，including nicotinic acid，3⁃indolepropionic acid，citric acid，linoleic acid，methylparaben，benzoic acid，and palmitoleic acid，covering organic acids，phenolic acids，and unsaturated fatty acids. Metabolic pathway analysis indicated that these compounds were primarily involved in the tricarboxylic acid（TCA）cycle，fatty acid biosynthesis，biosynthesis of unsaturated fatty acids，phenylalanine metabolism，nicotinate and nicotinamide metabolism，and tryptophan metabolism，providing a potential molecular basis for the antifungal activity of strain HJ⁃L. Therefore，the antagonistic strain HJ⁃L has the potential to be developed as a biological control agent against Zanthoxylum leaf mold and serves as a promising microbial resource for the biocontrol of this disease.

 

Key words: Zanthoxylum leaf mold, Alternaria alternata, Lactic acid bacteria, Leuconostoc suionicum, Antifungal activity, Biological control

摘要： 为筛选对花椒叶霉病病原菌链格孢菌（Alternaria alternata）具有拮抗作用的乳酸菌并探究其抑菌机制，从甘肃省陇南市健康花椒树体自然分泌的乳白色液体中分离乳酸菌，以链格孢菌为指示病原菌进行拮抗菌株筛选，结合形态学与分子生物学方法对拮抗菌株进行鉴定，并系统测定了其抑菌活性、代谢产物及生物学特性。结果表明，拮抗菌株HJ-L对链格孢菌的抑菌率达83.2%。经鉴定，菌株HJ-L属明串珠菌属，为Leuconostoc suionicum，其发酵液乙酸乙酯提取物对链格孢菌的最小抑菌质量浓度（MIC）和最小杀菌质量浓度（MFC）均为10.00 mg/mL，可导致菌丝形态异常。该拮抗菌株对腐皮镰刀菌、尖孢镰刀菌、层出镰刀菌、圆孔镰刀菌和松针刺盘孢菌5种植物病原真菌均表现出广谱抑菌活性，抑制率为62.5%~88.7%。代谢组学分析表明，从菌株HJ-L发酵液提取物中筛选出7种潜在抑菌物质，包括烟酸、3-吲哚丙酸、柠檬酸、亚油酸、对羟基苯甲酸甲酯、苯甲酸和棕榈油酸，涵盖有机酸类、酚酸类及不饱和脂肪酸。代谢通路分析显示，上述物质主要涉及三羧酸循环、脂肪酸生物合成、不饱和脂肪酸合成、苯丙氨酸代谢、烟酸和烟酰胺代谢以及色氨酸代谢等途径，为菌株HJ-L的抑菌作用提供了潜在的分子基础。因此，菌株HJ-L具有开发为花椒叶霉病生防菌剂的潜力，可作为花椒叶霉病生物防治的微生物资源。

关键词: 花椒叶霉病, 链格孢菌, 乳酸菌, 明串珠菌, 抑菌活性, 生物防治