Singhasuwan Somruethai, Choorit Wanna, Sirisansaneeyakul Sarote, Kokkaew Nakhon, Chisti Yusuf
Biotechnology Program, School of Agricultural Technology, Walailak University, Nakhon Si Thammarat 80161, Thailand.
Biotechnology Program, School of Agricultural Technology, Walailak University, Nakhon Si Thammarat 80161, Thailand.
J Biotechnol. 2015 Dec 20;216:169-77. doi: 10.1016/j.jbiotec.2015.10.003. Epub 2015 Oct 20.
Chlorella sp. TISTR 8990 was cultivated heterotrophically in media with various initial carbon-to-nitrogen ratios (C/N ratio) and at different agitation speeds. The production of the biomass, its total fatty acid content and the composition of the fatty acids were affected by the C/N ratio, but not by agitation speed in the range examined. The biomass production was maximized at a C/N mass ratio of 29:1. At this C/N ratio, the biomass productivity was 0.68gL(-1)d(-1), or nearly 1.6-fold the best attainable productivity in photoautotrophic growth. The biomass yield coefficient on glucose was 0.62gg(-1) during exponential growth. The total fatty acids (TFAs) in the freeze-dried biomass were maximum (459mgg(-1)) at a C/N ratio of 95:1. Lower values of the C/N ratio reduced the fatty acid content of the biomass. The maximum productivity of TFAs (186mgL(-1)d(-1)) occurred at C/N ratios of 63:1 and higher. At these conditions, the fatty acids were mostly of the polyunsaturated type. Allowing the alga to remain in the stationary phase for a prolonged period after N-depletion, reduced the level of monounsaturated fatty acids and the level of polyunsaturated fatty acids increased. Biotin supplementation of the culture medium reduced the biomass productivity relative to biotin-free control, but had no effect on the total fatty acid content of the biomass.
小球藻TISTR 8990在具有不同初始碳氮比（C/N比）的培养基中以及不同搅拌速度下进行异养培养。生物量的产量、其总脂肪酸含量和脂肪酸组成受C/N比的影响，但在所研究的搅拌速度范围内不受其影响。生物量产量在C/N质量比为29:1时达到最大值。在此C/N比下，生物量生产力为0.68gL(-1)d(-1)，几乎是光合自养生长中可达到的最佳生产力的1.6倍。指数生长期间，基于葡萄糖的生物量产率系数为0.62gg(-1)。冻干生物量中的总脂肪酸（TFA）在C/N比为95:1时最高（459mgg(-1)）。较低的C/N比会降低生物量的脂肪酸含量。TFA的最大生产力（186mgL(-1)d(-1)）出现在C/N比为63:1及更高时。在这些条件下，脂肪酸大多为多不饱和型。在氮耗尽后让藻类长时间处于稳定期，会降低单不饱和脂肪酸水平，多不饱和脂肪酸水平则会升高。向培养基中添加生物素相对于无生物素对照会降低生物量生产力，但对生物量的总脂肪酸含量没有影响。
