CBQF/Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Rua Dr. António Bernardino de Almeida, P-4200-072 Porto, Portugal.
Biotechnol Prog. 2011 Sep-Oct;27(5):1218-24. doi: 10.1002/btpr.649. Epub 2011 Jun 3.
Reactive forms of oxygen can damage DNA (among other molecules), thus triggering, e.g., atherogenesis and carcinogenesis. However, such dietary antioxidants as lutein and β-carotene can effectively inactivate them; these compounds were found to high levels in a novel strain (M2-1) of the microalga Scenedesmus obliquus. The independent and combined effects of pH and temperature on its rates of growth and production of antioxidants were experimentally assessed, via a full factorial experimental design; the effects of each parameter independently, and of their interactions were accordingly quantified by ANOVA. Our results indicated that temperature plays a more important role on the maximum specific growth rate than pH; in terms of antioxidant content, pH and, to a lesser extent, temperature also have relevant effects. Consequently, the highest rate of biomass specific growth (0.294 ± 0.013 day(-1)) and biomass productivity (0.837 ± 0.054 mg L(-1) day(-1)) were associated with relatively low pH (6) and relatively high temperature (30°C). Conversely, the antioxidant production rate increased with pH; hence, the highest productivity (0.638 mg L(-1) day(-1)) was attained at pH 8 and 30°C. At the best operating conditions for antioxidant content, the levels of lutein and β-carotene were 203.57 ± 1.41 and 18.20 ± 0.33 mg mL(-1), respectively; the maximum production of either one occurred at the early exponential phase.
活性氧会损害 DNA（以及其他分子），从而引发动脉粥样硬化和癌变等。然而，叶黄素和β-胡萝卜素等膳食抗氧化剂可以有效地使它们失活；在斜生栅藻（Scenedesmus obliquus）的一个新型菌株（M2-1）中发现了这些化合物的高含量。通过完全析因实验设计，实验评估了 pH 和温度对其生长速度和抗氧化剂产量的独立和联合影响；通过方差分析相应地量化了每个参数及其相互作用的影响。我们的结果表明，温度对最大比生长速率的影响比 pH 更大；就抗氧化剂含量而言，pH 和在较小程度上温度也有相关影响。因此，最高的生物质比生长速率（0.294±0.013 天（-1））和生物质生产率（0.837±0.054 mg L（-1）天（-1））与相对较低的 pH（6）和相对较高的温度（30°C）相关。相反，抗氧化剂的生产速率随 pH 增加而增加；因此，在 pH 8 和 30°C 时达到了最高的生产率（0.638 mg L（-1）天（-1））。在抗氧化剂含量的最佳操作条件下，叶黄素和β-胡萝卜素的含量分别为 203.57±1.41 和 18.20±0.33 mg mL（-1）；其中一种物质的最大产量出现在早期指数生长期。
