糖蜜对重组谷氨酸棒杆菌产L-丝氨酸的影响

Effect of Molasses on L-Serine Production by Recombinant Corynobacterium glutamicum

重组谷氨酸棒杆菌SYPS-062 33a△SSA-PS能够利用蔗糖直接发酵产L-丝氨酸。本文比较了不同的糖蜜预处理方法及其添加量对该重组菌的生长及产L-丝氨酸的影响,并进一步分析了糖蜜对丝氨酸合成相关途径中关键酶基因转录水平的影响。结果表明,糖蜜替代蔗糖作为唯一碳源时对产物合成并不利,但在蔗糖培养基中添加少量硫酸预处理的糖蜜有利于该菌的生长和产物积累。当其添加量为总糖量0.24%时,菌株生长最好,OD562可达76.37,L-丝氨酸产量为32.76 g/L,比未添加糖蜜的对照组分别提高了23.82%和29.44%。qRT-PCR结果表明,添加低质量分数糖蜜可显著提高EMP途径中关键酶基因的转录水平,这可能是促进产物积累的主要原因之一。

The recombinant Corynebacterium glutamicum SYPS-062 33aΔSSA-PS was an L-serine producing strain on sucrose.To study the effects of molasses,different pretreatment techniques and concentrations of molasses were tested on the growth of the strain and L-serine accumulation.For endogenous regulation,the effect of the transcription of genes in EMP pathway was studied.The result indicated that molasses as the sole carbon was not favorable to the synthesis of L-serine.While,with the addition of molasses with 0.24%sugar by the pretreatment with H2SO4,the strain showed a significant improvement in the cell growth(OD562=76.37)and L-serine(32.76 g/L)after 120 h of fermentation.Compared to the control,the cell growth and L-serine were improved by 23.82%and 29.44%,respectively.The results of qRT-PCR showed that the addition of molasses could significantly improve the transcription of genes in the EMP pathway,which was one of the reason why molasses could improve the production of L-serine.