原生质体紫外诱变选育可利用廉价碳源的高产油新菌株

【目的】研究并建立利用原生质体紫外诱变技术选育可利用廉价碳源发酵的高产油新菌株的方法。【方法】采用1.5%蜗牛酶和1.0%纤维素酶混合液水解去除细胞壁得到2A00015(近平滑假丝酵母,Candida parapsilosis)的原生质体,将其放于紫外灯下诱变及再生壁培养,筛选获得可利用廉价碳源发酵的高产油酵母,并采用气相色谱质谱联用法(GC-MS)测定其脂肪酸组成。【结果】突变效果最好的突变菌株2A00015/25用葡萄糖发酵培养7 d后,其生物量、油脂产率和产油量分别为17.77 g/L、58.12%和10.32 g/L,较原始菌株分别提高了12.45%、23.32%和38.68%;利用废糖蜜发酵培养,其生物量、油脂产率和产油量分别为18.54 g/L、49.44%和9.17 g/L,较原始菌株分别提高了9.09%、21.16%和32.18%。利用废糖蜜培养其产油效率虽低于利用葡萄糖培养,但从环境保护及原材料成本的角度考虑,用废糖蜜作为碳源发酵培养产生油脂更具优势。诱变菌株利用废糖蜜发酵后产生油脂经检测含有8种脂肪酸,其脂肪酸组成与植物油近似,其中不饱和脂肪酸含量占脂肪酸总量的82.4%。【结论】通过利用原生质体紫外诱变技术,成功选育出一株新的可利用廉价碳源的高产油海洋菌株,产油率达到49.4%,提高了21.2%。

Breeding high-yield oil-producing strain to use cheap carbon source by UV induced protoplast mutagenesis

Objective] We used UV induced protoplast mutagenesis to study breed a new high-yielding lipid-producing strain which could use cheap carbon source. Methods] Get the 1.5% glusulase and 1.0% cellulose solution. Hydrolyze to remove the cell wall and obtain the protoplast of 2A00015 (Candida parapsilosis). Put it under the ultraviolet lamp for mutagenesis and cultivate regenrated wall. Then screen to get the high oil generated yeast which could be fermented by low-cost carbon source. Determine its fat acid components by gas chromatography with mass spectrometric (GC-MS). Results] Cultivated the mutant strain with best mutation 2A00015/25 in the glucose. We found that the biomass, oil yield rate and oil production are separately 17.77 g/L, 58.12% and 10.32 g/L, which are separately 12.45%, 23.32% and 38.68% higher than the original strain. We have also cultivated the mutant strain in the waste molasses and found the biomass, oil yield rate and oil production are separately 18.54 g/L, 49.44% and 9.17 g/L, which are separately 9.09%, 21.16% and 32.18% higher than the original strain. The oil yield rate is lower in the waste molasses cultivation than that in glucose cultivation. However, in consideration of environment protection and cost of raw materials, the waste molasses is of much more advantages. It is tested that the fat generated from the waste molasses fermentation consists of eight kinds of fat acid. Its fat acid components are similar to the vegetable oil, in which the content of unsaturated fatty acid comprised 82.4% of the total fatty acid. Conclusion] Basing on UV induced protoplast mutagenesis, we have successfully bred a new high-yielding oil strain which can make use of the low-cost carbon source, with its oil production rate 49.4% which has increased by 21.2%.