Ray S, Bagchi S N
Department of Biological Sciences, Rani Durgavati University, Jabalpur 482 001, India.
New Phytol. 2001 Mar;149(3):455-460. doi: 10.1046/j.1469-8137.2001.00061.x.
• The change in algicide synthesis in response to nutrients and pH in axenic cultures of the planktonic cyanobacterium, Oscillatoria laetevirens is reported. • Analytical and bioassay techniques were used to determine the effects of nitrogen (N), sulpher (S), phosphorus (P), magnesium (Mg ), calcium (Ca ) and hydrogen (H ) on Oscillatoria laetevirens growth, secondary metabolite accumulation and minimum inhibitory concentration in culture filtrates. • Growth and secondary metabolite production were affected by nutrient addition. High algicide production, which was not dependent on optimal growth, correlated with deficiences of magnesium and phosphate, and high pH. Algicidal activity in the culture medium was not detected following organic nitrogen addition while optimal growth was sustained; however, ammonia reduced biomass yield but did not affect algicide formation. The differential algicide concentration inside the cells and in the culture medium indicated secretion by an efflux mechanism rather than leakage from aging cells. • Algicide production by Oscillatoria laetevirens was negatively regulated by both phosphate and magnesium, and by pH. The interactive influence of nutrients and allelopathy is discussed in species succession and dominance in the maintenance of freshwater blooms.
• 报道了浮游蓝藻优美颤藻无菌培养物中杀藻剂合成对营养物质和pH的响应变化。
• 采用分析和生物测定技术来确定氮（N）、硫（S）、磷（P）、镁（Mg）、钙（Ca）和氢（H）对优美颤藻生长、次级代谢产物积累以及培养滤液中最低抑菌浓度的影响。
• 营养物质添加会影响生长和次级代谢产物的产生。高杀藻剂产量与镁和磷酸盐缺乏以及高pH相关，且不依赖于最佳生长。添加有机氮后未检测到培养基中的杀藻活性，但维持了最佳生长；然而，氨降低了生物量产量，但不影响杀藻剂形成。细胞内和培养基中杀藻剂浓度的差异表明其通过外排机制分泌，而非来自衰老细胞的泄漏。
• 优美颤藻的杀藻剂产生受到磷酸盐、镁和pH的负调控。在淡水水华维持过程中的物种演替和优势地位方面，讨论了营养物质和化感作用的相互影响。
