青贮玉米优良乳酸菌的分离与筛选

目的从青贮玉米中分离和筛选乳酸菌并进行鉴定，为青贮饲料提供优良菌种，对改善青贮饲料品质具有重要指导意义。方法以青贮60 d的全株青贮玉米为材料，采用MRS平板分离培养的方法分离培养菌株，通过形态学特征、产酸速率和生长曲线筛选优质乳酸菌，并对其16S rDNA序列进行分析。结果共分离出7株乳酸菌(Z₁~Z₇)。生理生化分析表明：Z₂和Z₄菌株产酸能力较低，Z₅和Z₆菌株虽然产酸能力强但菌株生长速率缓慢，而Z₁、Z₃和Z₇菌株产酸能力强且生长速率快。16S rDNA序列分析显示：Z₁、Z₃和Z₇菌株与植物乳杆菌(Lactobacillus plantarum)的相似度均达99%以上。结论Z₁、Z₃和Z₇乳酸菌具有良好的青贮潜力，可作为制备青贮添加剂的备选菌种。

The Isolation and Identification of Lactic Acid Bacteria from Silage Corn

PurposeThe separation, screening and identification of lactic acid bacteria from silage corn provides excellent strains for silage, which has important guiding significance for improving the quality of silage. MethodUsing the whole plant silage maize silaged for 60 days as the material, the strain was isolated and cultivated by the method of MRS plate separation and culture. Furthermore, the excellent lactic acid bacteria was screened by morphological characteristics, acid production rate, growth curve and analysis of 16S rDNA sequence. ResultsA total of seven lactic acid bacteria strains (Z₁-Z₇) were isolated. Physiological and biochemical analysis showed that the Z₂ and Z₄ strains had low acid production capacity. Although Z₅ and Z₆ strains had strong acid production capacity, their growth rate was slow. Z₁, Z₃ and Z₇ strains have high acid production capacity and fast growth rate. Analysis of 16S rDNA sequence showed that the Z₁, Z₃ and Z₇ strains were all Lactobacillus plantarum, with a similarity of more than 99%. ConclusionZ₁, Z₃ and Z₇ lactic acid bacteria have good silage potential and can be used as candidate strains for preparing silage additives.