【作者】 张娜；

【导师】 郭美锦；

【作者基本信息】 华东理工大学 ， 微生物学， 2012， 硕士

【摘要】 本文对三株饲用乳杆菌进行了鉴定,并对其生理特性和发酵过程的菌体生长特性进行了研究,菌体的生物量有了较大提高的同时,生产成本得到了降低。对三株饲用乳杆菌SJ2-1、SJ2-2和SJ2-3进行16S rDNA分析鉴定。结果显示乳杆菌SJ2-1为Lactobacillus satsumensis,乳杆菌SJ2-2为干酪乳杆菌(Lactobacillus casei),乳杆菌SJ2-3为Lactobacillus sp.71。乳杆菌SJ2-1、SJ2-2和SJ2-3的16SrDNA序列分别经过比对后,构建了系统发育树。对乳杆菌SJ2-1和乳杆菌SJ2-2两菌株进行生理特性研究。结果显示,乳杆菌SJ2-1能够耐受5%NaCl,2.0g/L牛胆盐,能在pH3.5的培养基中生长,乳杆菌SJ2-2能够耐受7%NaCl,2.5g/L牛胆盐,能在pH2.5的培养基中生长,考察的两株乳杆菌都能在45℃生长,说明耐热性较好。以玉米浆为原料,采用响应面法对干酪乳杆菌SJ2-2的菌体生长培养基进行优化。优化后的干酪乳杆菌SJ2-2菌体生长最佳培养基为：工业葡萄糖36g/L,玉米浆50.4ml/L,无水乙酸钠10.42g/L,MgSO4·7H2O为0.2g/L,MnSO4·H2O为0.01g/L,FeSO4·7H2O为0.01g/L,NaCl为0.01g/L,吐温80为1ml/L。在此最优条件下,干酪乳杆菌菌体生物量OD600值达到3.686,比优化前提高了81.8%。研究了乳杆菌SJ2-1、SJ2-2和SJ2-3在5L罐中分批培养的生长特性。结果表明在优化培养基中干酪乳杆菌SJ2-2最大菌体生物量比在GYP培养基中提高了84.5%,优化得到进一步验证。在优化后的玉米浆培养基中进行分批培养,分别研究了这三株乳杆菌的生长动力学模型并对相关参数进行了分析。更多还原

【Abstract】 In this paper,Lactobacillus SJ2-1、SJ2-2and SJ2-3applied in feed were identified by16S rDNA sequencing and their biological characteristics and growth property during fermentation process were studied.The bacterial biomass was greatly improved, thus the production costs decreased.Lactobacillus SJ2-1, Lactobacillus SJ2-2, Lactobacillus SJ2-3were identified as Lactobacillus satsumensis, Lactobacillus casei and Lactobacillus sp.71. by16S rDNA sequenceing, respectively. Phylogenetic tree was constructed by16S rDNA sequencing and blast from three Lactobacillus strains.Lactobacillus SJ2-1and SJ2-2were studied on their biological characteristics.The results showed that Lactobacillus SJ2-1can tolerate a5%NaCl and2.0g/L bile salt and can be grown in pH3.5medium, Lactobacillus SJ2-2can tolerate a7%NaCl,2.5g/L bile salt and can be grown in pH2.5medium, two strains both can be grown at45℃with good heat resistance.The optimal medium for biomass growth by using RSM was obtained as follows: industrial glucose36g/L,corn steep liquor50.4ml/L,NaAc10.42g/L, MgSO4·7H2O0.2g/L, MnSO4·H2O0.01g/L, FeSO4·7H2O0.01g/L, NaCl0.01g/L,1ml/L Tween-80. Under the optimal condition, the biomass OD600of Lactobacillus casei SJ2-2reached3.686, increased by81.8%, compared to the culture with original medium.Three Lactobacillus strains were also studied on growth property in a5L fermentor.The results indicated that the maximum biomass of Lactobacillus casei SJ2-2increased by84.5%in the optimized medium than that in GYP medium, proving successful optimization by response surface methodology. Finally, the growth dynamics models for batch culture of three Lactobacillus strains were also studied and the related parameters were analyzed.更多还原