Ashy M A, Abou-Zeid A
Zentralbl Mikrobiol. 1982;137(5):387-94.
Different local active yeasts were isolated from air, soils, and muddy sludges. Potentialities and capabilities of 67 yeasts isolates for formation of SCP (single-cell protein) were evaluated by their cultivation on the fermentation medium, containing diesel oil as sole carbon source to select the most efficient yeast isolates. Identification of the most active organisms revealed that Candida tropicalis and Yarrowia lipolytica were the most efficient yeasts, having potentialities for SCP production. Biochemical changes which occurred during the fermentative production of SCP by Candida tropicalis revealed that during the fermentation process a deep in pH towards the acid side was recorded, and this might be due to the formation of certain organic acids with the beginning of fermentation. Yields of yeast cell biomass increased with the increase of fermentation period, reaching its optimum at 168 h, above which a decline in SCP was observed. High diesel oil concentrations in the fermentation medium harmed yeast growth and consequently a decrease in cell biomass was observed, while low diesel oil concentrations, especially in the range of 40--60 ml/litre, gave high titres of SCP. Addition of diesel oil at different intervals of the fermentation process-promoted yield of SCP.
从空气、土壤和泥状污泥中分离出了不同的本地活性酵母。通过在以柴油作为唯一碳源的发酵培养基上培养67株酵母分离株，评估了它们形成单细胞蛋白（SCP）的潜力和能力，以筛选出最有效的酵母分离株。对最具活性的微生物进行鉴定后发现，热带假丝酵母和解脂耶氏酵母是最有效的酵母，具有生产SCP的潜力。热带假丝酵母发酵生产SCP过程中发生的生化变化表明，在发酵过程中记录到pH值向酸性方向大幅下降，这可能是由于发酵开始时形成了某些有机酸。酵母细胞生物量的产量随着发酵时间的增加而增加，在168小时达到最佳值，超过此时间后SCP产量下降。发酵培养基中柴油浓度过高会损害酵母生长，因此观察到细胞生物量减少，而柴油浓度较低，尤其是在40-60毫升/升范围内，会产生高滴度的SCP。在发酵过程的不同时间间隔添加柴油可提高SCP产量。
