菌体比生长速率及不同培养基成分变化对解脂假丝酵母中RNA累积的影响

为了研究解脂假丝酵母ATCC 20408菌株比生长速率和培养基中氨基酸成分对酵母RNA累积的影响。采用分批和连续培养的方法，解脂假丝酵母分别在发酵培养基、YPD培养基、糖蜜培养基以及不含玉米浆的成纤维细胞培养基（FM）中进行培养。结果表明，在分批培养的不同生长期，菌体细胞内RNA累积量有明显区别；在对数生长期时，RNA含量达干重的11.8%(g-RNA/g-DCW)；稳定期时，RNA含量仅为6.9%。连续培养时，酵母RNA比生长速率越大，酵母RNA积累量越高，当细胞比生长速率为0.5 h^-1时，RNA含量可达15.6%，糖的转化率为42.8%。在不含玉米浆的FM培养基中加入不同的氨基酸组分进行有氧分批培养时，添加混合氨基酸或蛋白胨组分均可提高酵母细胞RNA的含量。本研究首次报道了高比生长速率和混合氨基酸组分对解脂假丝酵母细胞RNA的积累具有明显的促进作用，而比生长速率对酵母RNA的累积影响更大。

High RNA accumulation in Candida tropicalis is affected by specific growth rate and different medium composition

Batch and continuous fermentation were adopted to investigate the effect of specific growth rate and amino acid components on RNA accumulation inCandida tropicalis ATCC 20408 in fermentation medium (FM),yeast peptone dextrose medium (YPD),molasses fermentation medium (MFM) and FM without corn steep liquor. The data showed that obvious differences in intracellular RNA accumulation were observed at different cell growth phases in bath fermentation prosess,and RNA level reached 11.8%(g-RNA /g-DCW) during exponential phase,and only 6.9% during stationary phases. It was also found that intracellular RNA accumulation increased with the increase of specific growth rate in continue fermentation prosess,and the highest RNA level reached 15.6% with the glucose conversion rate of 42.8% at the dilution rate of 0.5 h^-1. Furthermore,the data showed that RNA lever was notably increased in batch fermentation process when amino acids or peptone was added into the fermentation medium containing no corn steep liquor. Taken together,it was reported for the first time that specific growth rate and amino acid components plays a leading role on the intracellular RNA accumulation in C.tropicalis,and specific growth rate is more important.