一株近平滑假丝酵母的分离、鉴定和产油的研究

摘要

In order to gain the yeast with high oil yield for preparing biodiesel and isolating one yeast strain,cloning and sequencing of its internal transcribed region (ITS region) of RNA gene was performed by molecular biology technique.Also it is compared with the existing gene sequences in GenBank.At the same time,the growth and development of this strain were studied.The biomass,carbohydrate and nitrogen metabolism,lipid content and fatty acid composition were also test and analyzed in our study.Results showed that firstly the strain ITS sequence length was 479 bp,compared with the Candida parapsilosis in GenBank,the homology rate was close to 100％.Results of morphological and molecular biology identification showed that the strain was Candida parapsilosis.Secondly the number of bacteria increased steadily during 0 ～ 12 h.Sugar and nitrogen consumed obviously.It is the adaptation period of Candida parapsilosis;during 12 ～ 48 h the bacterias propagated rapidly.Sugar and nitrogen consumption were very significant.It is the Logarithmic phase of Candida parapsilosis;during 48 ～ 120 h,the number of bacteria remained stable and no longer increased.Sugar and nitrogen consumed stably.It is the stable phase of Candida parapsilosis;after 120 h,the number of bacteria decreased.Sugar and nitrogen were all consumed.It is the recession period of Candida parapsilosis;thirdly the accumulation value of intracellular oil reached the maximum at 120 h.Oil yield was 4.5 g/L,and the oil content was about 22％,the fatty acid composition was mainly oleic acid,and contained a small amount of palmitic acid and linoleic acid.It can be seen from the results that there are some prospects of this yeast for the production of bio diesel oil.This paper lays a foundation for adjusting the content of medium to increase the oil yield.%为了制备生物柴油而获得高产油脂的酵母,分离出1株产油酵母,利用分子生物学技术对其RNA基因内转录区(ITS区)进行了克隆测序,并与GenBank中已有的菌株基因序列进行比对;同时,对该菌株生长发育和油脂合成进行了研究;对生物量、糖氮代谢、油脂含量以及脂肪酸组分进行了检测分析.结果表明:该菌株ITS序列长度为479 bp,与GenBank中近平滑假丝酵母相比较同源率接近100％,形态结果和分子生物学鉴定表明该菌株为近平滑假丝酵母;该茵在0～12h期间茵体数量稳定增长,糖氮消耗明显为近平滑假丝酵母的发酵适应期;12 ～48 h,此时菌种快速繁殖,糖氮消耗非常显著,为近平滑假丝酵母的对数期;48～120 h,菌体数量保持稳定基本不再增长,糖氮消耗稳定为近平滑假丝酵母的稳定期;120 h以后,菌体数量减少,糖氮基本消耗完毕为近平滑假丝酵母的衰退期;在120 h左右胞内油脂积累达到最大值,油脂产量为4.5g/L,含油率约为22％,脂肪酸组成主要以油酸为主,并含有少量棕榈酸和亚油酸.因此,该菌作为油脂菌株生产生物柴油具有一定前景,为以后调整培养基含量来增加菌种油脂产量提供了参考.