摘要
[目的]以猪链球菌2型NT15B菌株为研究对象,通过优化发酵培养基组分提高菌株活菌数,降低生产成本,为猪链球菌2型NT15B菌株的高密度培养及猪链球菌病疫苗的大规模生产和推广提供参考.[方法]试验以培养的猪链球菌2型NT15B菌株最高活菌数为筛选指标,通过单因素试验筛选菌株发酵培养基中碳源、氮源(有机氮源和无机氮源)、无机盐金属离子、磷酸缓冲液的最佳组分及浓度,并根据单因素筛选结果选择碳源浓度、有机氮源总浓度、有机氮源比例、磷酸盐缓冲液浓度4个因素各3个水平设计正交试验,并进一步进行多因素的筛选与验证.[结果]猪链球菌2型NT15B菌株发酵培养基最优条件为6.0 g/L蔗糖、1.0 g/L尿素、10 g/L酵母提取物YE7 与 20 g/L 酵母蛋白胨 Nucel 887 混合氮源,1.0 g/L NaCl、9.58 g/L K2 HPO4·3H2O、1.09 g/L KH2PO4、1 mmol/L MgSO4·7H2O、0.3 g/L L-抗坏血酸.采用此最优组合,摇瓶培养猪链球菌2型NT15B活菌数最高达80.83×108 CFU/mL,较优化前提高256.08％.[结论]优化后的培养基能有效提高猪链球菌2型NT15B菌株活菌数,降低了生产成本,为发酵罐水平的优化提供参考.
Abstract
[Objective]The experiment took Streptococcus suis type 2 NT15B strain as the research object.By optimizing the fermentation medium components,the viable counts of the strain was increased and the production cost was reduced,so as to provide a reference for high-density culture of Streptococcus suis type 2 NT15B strain and the research related to the large-scale production and promotion of the vaccine against porcine streptococcal disease.[Method]The maximum viable counts of Streptococcus suis type 2 NT15B strain was used as the screening index,and the optimal components and concentrations of carbon sources,nitrogen sources(organic and inorganic nitrogen sources),inorganic salt metal ions,and phosphoric acid buffers in the fermentation medium of the strain were screened by single-factor test.According to the results of single factor screening,3 levels of each of 4 factors,carbon source concentration,total organic nitrogen source concentration,organic nitrogen source proportion and phosphate buffer concentration,were selected to design orthogonal tests,and further multi-factor screening and verification were carried out.[Result]The optimal fermentation medium of Streptococcus suis type 2 NT15B strain was 6.0 g/L sucrose,1.0 g/L urea,10 g/L yeast extract YE7 mixed with 20 g/L yeast peptone Nucel 887 as nitrogen sources,1.0 g/L NaCl,9.58 g/L K2 HPO4·3H2O,1.09 g/L KH2PO4,1 mmol/L MgSO4·7H2O and 0.3 g/L L-ascorbic acid.Using this optimal combination,the viable counts of Streptococcus suis type 2 NT15B strain at the shaking flask level was 80.83×108 CFU/mL,which was 256.08％higher than before optimization.[Conclusion]The optimized medium effectively increased the viable counts of Streptococcus suis type 2 NT15B strain,reduced production costs and provided a reference for optimization in fermenters.
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