小球藻联产油脂和虾青素的基元模式分析

构建了包含虾青素合成途径的小球藻代谢网络模型,集成文献报道同位素标定的小球藻代谢通量数据,估算了胞内代谢通量分布。在正常和缺氮培养条件下,虾青素的代谢通量分别为0.38和0.35。计算得到基元模式共640条,通过最大熵原理算法求取了正常培养和缺氮培养条件下的基元模式概率。存在4条关键基元模式,在2种培养条件下,其基元模式概率之和分别为60.95%和77.53%。虾青素的最大理论合成产率为11.27%,但是这4条关键基元模式并不包括虾青素的合成反应。

Elementary mode analysis of Chlorella sp for producing lipid and astaxanthin

Combined producing lipid and high value added products were possible to decrease the production cost and improve the economic benefit. The concentration of astaxanthin in Chlorella sp. was lower than that in Haematococcus pluvialis. The astaxanthin was possible for commercial development after the extraction of lipids in large scale cultivation of Chlorella sp. A metabolic network of Chlorella sp. including astaxanthin synthesis pathway was reconstructed. The intracellular flux distribution was estimated by integrating 13 C tracer metabolic fluxes. The metabolic fluxes of astaxanthin under normal and nitrogen limited conditions were 0.38 and 0.35, respectively. A total of 640 elementary modes was obtained based on this metabolic network model. The probabilities of these elementary modes were evaluated by the maximal entropy principle algorithm under normal and nitrogen limited conditions. There are four dominant elementary modes with the largest probabilities for both conditions. The total contributions of these four elementary modes were 60.95% under normal condition and 77.53% under nitrogen limited conditions. The largest yield of astaxanthin was 11.27% but the astaxanthin formation was not included in these dominant elementary modes.