Rosa Rinamara Martins, Machado Mariana, Vaz Marcelo Gomes Marçal Vieira, Lopes-Santos Regina, Nascimento Antônio Galvão do, Araújo Wagner L, Nunes-Nesi Adriano
National Institute of Science and Technology on Plant Physiology under Stress Conditions, Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900 Viçosa, Minas Gerais, Brazil.
Departamento de Microbiologia, Universidade Federal de Viçosa, 36570-900 Viçosa, Minas Gerais, Brazil.
J Biotechnol. 2023 Apr 10;367:20-30. doi: 10.1016/j.jbiotec.2023.03.009. Epub 2023 Mar 24.
Microalgae is a potential source of bioproducts, including feedstock to biofuels. Urea has been pointed as potential N source for microalgae growth. Considering that urea metabolism releases HCO to the medium, we tested the hypothesis that this carbon source could improve photosynthesis and consequently growth rates of Chlamydomonas reinhardtii. In this sense, the metabolic responses of C. reinhardtii grown with ammonium and urea as nitrogen sources under mixotrophic and autotrophic conditions were investigated. Overall, the mixotrophy led to increased cell growth as well as to a higher accumulation of lipids independent of N source, followed by a decrease in photosynthesis over the growth phases. In mixotrophy, urea stimulates growth in terms of cell number and dry weight. Furthermore, higher photosynthesis was verified in late logarithmic phase compared to ammonium. Under autotrophy conditions, although cell number and biomass were reduced, there was higher production of starch independent of N source. Nonetheless, urea-based autotrophic treatments stimulated biomass production compared to ammonium-based treatment. Under mixotrophy higher input of carbon into the cell from acetate and urea optimized photosynthesis and consequently promoted cell growth. Together, these results suggest urea as alternative source of carbon, improving photosynthesis and cell growth in C. reinhardtii.
微藻是生物产品的潜在来源，包括生物燃料的原料。尿素已被指出是微藻生长的潜在氮源。鉴于尿素代谢会向培养基中释放HCO，我们检验了这样一个假设，即这种碳源可以改善光合作用，从而提高莱茵衣藻的生长速率。从这个意义上说，研究了在混合营养和自养条件下，以铵和尿素作为氮源培养的莱茵衣藻的代谢反应。总体而言，无论氮源如何，混合营养都会导致细胞生长增加以及脂质积累增加，随后在生长阶段光合作用会下降。在混合营养中，尿素在细胞数量和干重方面刺激生长。此外，与铵相比，在对数后期验证了更高的光合作用。在自养条件下，尽管细胞数量和生物量减少，但无论氮源如何，淀粉产量都更高。尽管如此，与基于铵的处理相比，基于尿素的自养处理刺激了生物量的产生。在混合营养中，来自乙酸盐和尿素的更高碳输入优化了光合作用，从而促进了细胞生长。总之，这些结果表明尿素是碳的替代来源，可改善莱茵衣藻的光合作用和细胞生长。
