抑制黄曲霉乳酸菌的筛选与鉴定

The Screening and Identification of Lactic Acid Bacteria Against Aspergillus flavus

黄曲霉是玉米(Zea mays L.)青贮过程的主要污染物之一,本研究旨在从玉米青贮饲料中分离筛选出能够抑制黄曲霉菌生长的乳酸菌,为改善和提高青贮饲料品质提供优良菌种。本试验采用双层平板法,从玉米青贮饲料中筛选抑制黄曲霉的菌株,并对其进行生理生化鉴定及同源性分析,构建系统发育树,明确各菌株的分类地位。结果表明:从青贮发酵不同阶段筛选得到50株乳酸菌,其中有7株乳酸菌对黄曲霉有明显抑制作用(P<0.05),抑菌圈直径均大于3.60 cm,均为革兰氏阳性同型发酵乳酸菌,7株乳酸菌中Q39(49.40%)和Q40(49.60%)抑菌效果最好,抑菌圈直径为4.15 cm和4.17 cm,显著高于其他5株乳酸菌(P<0.05);菌株Q11,Q28,Q40,Q44与22种碳水化合物作用均呈阳性,菌株Q39和Q49与鼠李糖作用呈阴性,与松三糖反应呈弱阳性,菌株Q13相较于其他6株菌株对于碳源的利用情况较弱;经16S rDNA鉴定确定菌株Q39和Q49为植物乳杆菌,Q11,Q13,Q29,Q40,Q44为戊糖乳杆菌。菌株Q39和Q40可作为全株玉米青贮发酵的备选添加菌株。

Aspergillus flavus is one of the main pollutants in the process of corn silage.Lactic acid bacteria which can inhibit the growth of Aspergillus flavus were isolated and screened from corn silage to provide excellent strains for improving the quality of silage.The strains inhibiting Aspergillus flavus were screened from corn silage by double-layer plate method,and their physiological and biochemical identification and homology analysis were carried out.The phylogenetic tree was constructed to clarify the taxonomic status of each strain.Fifty strains of lactic acid bacteria were screened from different stages of silage fermentation,among which 7 strains showed significant inhibition against Aspergillus flavus(P<0.05),and the diameter of inhibition zone of the strains was greater than 3.60 cm.All of them were Gram-positive homofermentative lactic acid bacteria.Among the 7 strains of lactic acid bacteria,Q39(49.40%)and Q40(49.60%)had the best antibacterial effect,and the diameter of inhibition zone was 4.15 cm and 4.17 cm respectively,which was significantly higher than that of the other 5 strains of lactic acid bacteria(P<0.05);Strains Q11,Q28,Q40,and Q44 were positive to 22 types of carbohydrates.Strains Q39 and Q49 were negative to rhamnose and weakly positive to triose.Strain Q13 had weaker utilization of carbon sources than the other 6 strains.Strains Q39 and Q49 were identified as Lactiplantibacillus plantarum by 16S rDNA identification,and strains Q11,Q13,Q29,Q40 and Q44 were identified as Lactiplantibacillus pentosus.Strains Q39 and Q40 can be selected as alternative strains for whole-plant corn silage fermentation.