酵母粉对出芽短梗霉发酵普鲁兰多糖相对分子质量的影响

摘要

The effect of different concentration of yeast extract on pullulan yield,structure,and molecular weight ware studied by using A ureobasidium pullulans CGMCC 11062.The results showed that the pullulan yield and molecular weight were significantly influenced but the structure had not been effected by different concentration of yeast extract.The contents of biomass,pullulan and residual sugar were respectively 5.29 g/L,34.74 g/L,44.18 g/L,when yeast extract were absent in the medium.The highest yield could reach 61.32 g/L,when the concentration of yeast extract was 1.5 g/L.Nevertheless,excessive yeast powder supply caused carbon source flowing to the organism,pullulan yield reduction.The maximal molecular weight of pullulan were produced with no yeast extract medium,which is 529 528 Da.With the increase of the concentration of yeast powder,the pullulan molecular weight gradually decreased from 529 528 reduced to 183 278.The results showed that the yeast extract may induce pullulan degrading enzymes,and lead to the decrease of the yield and molecular weight.These studies could provide technical guidance for the different pullulan production.%以出芽短梗霉(A ureobasidium pullulans)CGMCC.11062为出发菌株,研究了不同质量浓度酵母粉对普鲁兰多糖产量、结构及相对分子质量的影响.结果表明酵母粉质量浓度对出芽短梗霉的产量和相对分子质量影响显著,而普鲁兰多糖的结构基本不受其影响.在未加酵母粉时,菌体质量浓度5.92 g/L,普鲁兰多糖产量34.74 g/L,残糖质量浓度44.18 g/L,而当酵母粉质量浓度为1.5 g/L时,普鲁兰多糖的产量出现最大峰值,达到了61.32 g/L,然而,过多的酵母粉供给造成了碳源流向生物体,普鲁兰多糖产量减少.未加酵母粉时生产的普鲁兰多糖相对分子质量最大,重均相对分子质量眠为529 528,随着酵母粉质量浓度的增加,生成的普鲁兰多糖相对分子质量逐渐降低,重均相对分子质量MW从529 528降低到183 278,表明酵母粉可能会诱导普鲁兰多糖降解酶的产生,并导致普鲁兰多糖相对分子质量及产量的降低.这些研究为不同特性普鲁兰多糖的生产提供技术指导.