Abstract

The commercial reality of microalgal biotechnology for the production of individual bioactives is constrained by the high cost of production and requires a biorefinery approach. In this investigation, we examined the influence of different nutrient deprivation (nitrogen (N), phosphorus (P), sulphur (S) and manganese (Mn)) on growth, chlorophyll a (Chl a), biohydrogen (H₂) and fatty acid profiles in Parachlorella kessleri EMCCN 3073 under both aerobic and anaerobic conditions. Anaerobic conditions combined with the nutrient deprivation resulted in cell division blockage, reduction in Chl a and remarkable changes in pH, whereas a significant increase in the H₂ production was observed after 24 h. The highest cumulative H₂ productivity was observed in N-deficient medium (300 μL/L, day 9) followed by Mn-deficient medium (250 μL/L, day 7). The highest H₂ production rate (3.37 μL/L/h) was achieved by Mn-deficient medium after 24 h. In terms of fatty acid composition, P. kessleri exhibited a differential response to different nutrient stresses. Under aerobic conditions, N-deficient media resulted in the highest lipid content (119% compared to control, day 7), whereas earlier lipid induction at (1–3 days) was observed with Mn- and S-deficient media with 18–91% and 25–34% increase, respectively, compared with the replete control. Meanwhile, higher lipid content was observed under anaerobic conditions combined with Mn-, N-, P- and S-deprived media (day 1) with 20%, 13%, 8% and 7% increases respectively compared with the control. This investigation, for the first time clearly, highlights the potential of P. kessleri as a sustainable biorefinery platform, for H₂ and fatty acid bio-production under anaerobic conditions.

Key points

• Parachlorella kessleri could provide a future sustainable biorefinery platform.

• Nutrient-deprived anaerobic conditions blocked cell growth but differentially induced H ₂ production.

• Nutrient status, under both aerobic/anaerobic conditions, alters lipids and fatty acids profile of P. kessleri.

• Nutrient-deprived (N- and Mn-) anaerobic conditions: future biorefinery platform.

中文翻译：

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营养状况对鹦鹉螺小球藻生物氢和脂质生产力的影响：一种生物精炼方法

摘要

用于生产单个生物活性物质的微藻生物技术的商业现实受到生产成本高的限制，并且需要生物精炼方法。在这项研究中，我们研究了不同营养剥夺（氮（N），磷（P），硫（S）和锰（Mn））对生长，叶绿素a（Chl a），生物氢（H ₂）和脂肪的影响。在好氧和厌氧条件下，小菜蛾小球藻EMCCN 3073中的酸性分布。厌氧条件与营养剥夺相结合导致细胞分裂阻塞，Chl a降低和pH值显着变化，而H ₂显着增加24小时后观察到生产。在缺氮培养基（300μL/ L，第9天）中观察到最高的累积H ₂生产率，其次是缺锰培养基（250μL/ L，第7天）。24小时后，通过缺锰培养基获得最高的H ₂生成速率（3.37μL/ L / h）。在脂肪酸组成方面，P。kessleri对不同的营养胁迫表现出不同的响应。在有氧条件下，缺氮培养基导致最高的脂质含量（与对照组相比，第7天为119％），而在Mn和S缺乏培养基中（18-91）观察到较早的脂质诱导（1-3天）与完全控制相比，分别增加了％和25–34％。同时，在缺氧条件下，与缺锰，缺氮，缺磷和缺硫的培养基（第1天）相结合，脂类含量更高，分别比对照组增加20％，13％，8％和7％。这项研究首次清楚地凸显了P. kessleri作为可持续的生物精炼平台的潜力，用于在厌氧条件下生产H ₂和脂肪酸。

关键点

•凯氏小球藻可以提供未来的可持续生物精炼平台。

•营养剥夺的厌氧条件阻止细胞生长，但差异诱导H ₂产生。

•在有氧/无氧条件下，营养状况都会改变凯斯勒假单胞菌的脂质和脂肪酸谱。

•缺营养（N和Mn）的厌氧条件：未来的生物精炼平台。