念珠藻中聚-β-羟基丁酸酯的积累：受pH值、光暗周期、氮和磷状况以及碳源的调控
Accumulation of poly-beta-hydroxybutyrate in Nostoc muscorum: regulation by pH, light-dark cycles, N and P status and carbon sources.
作者信息
Sharma Laxuman, Mallick Nirupama
机构信息
Agricultural and Food Engineering Department, Indian Institute of Technology, Kharagpur 721 302, India.
出版信息
Bioresour Technol. 2005 Jul;96(11):1304-10. doi: 10.1016/j.biortech.2004.10.009. Epub 2004 Dec 19.
Accumulation of poly-beta-hydroxybutyrate (PHB) in Nostoc muscorum was studied. Cells harvested at stationary phase of growth depicted maximum accumulation i.e. 8.6% (w/w) of dry cells as compared to lag (4.1%) or logarithmic (6.1%) phases of cultures. In contrast to alkaline pH, acidic pH, continuous illumination and cells grown in presence of combined nitrogen sources, such as NH(4)Cl and KNO(3), were found to affect PHB accumulation negatively. However, P-deficiency and addition of exogenous carbon sources (acetate, glucose, maltose, fructose and ethanol) were found stimulatory for PHB accumulation. In this report PHB accumulation in N. muscorum was boosted up to 35% (w/w) of dry cells when cells supplemented with 0.2% acetate were subjected to dark incubation for 7 days. Further studies are needed at metabolic engineering level or to apply genetic engineering techniques to improve the expression level of PHB photoproduction in cyanobacteria.
对念珠藻中聚-β-羟基丁酸酯（PHB）的积累进行了研究。在生长稳定期收获的细胞呈现出最大积累量，即占干细胞的8.6%（w/w），相比之下，培养的延迟期（4.1%）或对数期（6.1%）积累量较低。与碱性pH值相反，酸性pH值、持续光照以及在诸如氯化铵和硝酸钾等组合氮源存在下生长的细胞，被发现会对PHB积累产生负面影响。然而，磷缺乏和添加外源碳源（乙酸盐、葡萄糖、麦芽糖、果糖和乙醇）被发现对PHB积累具有刺激作用。在本报告中，当补充有0.2%乙酸盐的细胞进行7天黑暗培养时，念珠藻中PHB的积累量提高到了占干细胞的35%（w/w）。在代谢工程层面或应用基因工程技术来提高蓝细菌中PHB光合成的表达水平方面，还需要进一步研究。
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