Gao Baoyan, Hong Jian, Chen Jiamin, Zhang Hu, Hu Ren, Zhang Chengwu
Department of Ecology, Research Center for Hydrobiology, Jinan University, Guangzhou, 510632, People's Republic of China.
Biotechnol Biofuels Bioprod. 2023 Jan 19;16(1):12. doi: 10.1186/s13068-022-02249-0.
Microalgae are promising feedstocks for production of renewable biofuels and value-added bioproducts. Temperature and nitrogen supply are important environmental and nutritional factors affecting the growth and metabolism of microalgae, respectively. In this study, the growth and lipid accumulation of filamentous microalgae Xanthonema hormidioides under different temperatures (5, 7, 10, 15, 20, 25, 27 and 30 °C) and initial nitrogen concentrations (3, 9, 18 mM) were investigated, and its adaptive mechanisms of tolerance to low temperature and nitrogen stress were analysis by proteomics.
The optimum temperature range for the growth of X. hormidioides was between 15 and 20 °C, and the algal cells had slow growth rate at 5 °C and could not survive at 30 °C. The maximum biomass concentration was 11.73 g L under the temperature of 20 °C, and the highest total lipid content was 56.63% of dry weight. Low temperature did not change the fatty acids profiles but promoted the accumulation of unsaturated fatty acids of X. hormidioides. The maximum contents of palmitoleic acid, eicosapentaenoic acid and total fatty acid were 23.64%, 2.49% and 41.14% of dry weight, respectively. Proteomics was performed under three temperature (7, 15, 25 °C), two nitrogen concentrations (3 and 18 mM) and two cultivation times (day 3 and 12). A total of 6503 proteins were identified. In the low temperature, photosynthesis-related proteins were down-regulated to protect the photosynthetic apparatus. The up-regulation of key enzymes DGAT and PDAT demonstrated the accumulation of TAGs under low nitrogen treatment. The proteins related to ribosome, phosphatidylinositol signaling system, antioxidant system and cold shock proteins (CSPs) in X. hormidioides were co-upregulated under the treatment of low temperature, which can alleviate the damages induced by temperature stress and maintain the normal growth and metabolism of algal cells.
X. hormidioides is a psychrotolerant microalga. It is an oleaginous filamentous microalga containing hyper palmitoleic acid and a certain amount of eicosapentaenoic acid with great potential for biofuel development, as well as for applications in nutritional health products and other industries.
微藻是生产可再生生物燃料和增值生物产品的有前景的原料。温度和氮供应分别是影响微藻生长和代谢的重要环境和营养因素。本研究调查了丝状微藻霍氏黄丝藻在不同温度（5、7、10、15、20、25、27和30℃）和初始氮浓度（3、9、18 mM）下的生长和脂质积累情况，并通过蛋白质组学分析了其对低温和氮胁迫的耐受适应机制。
霍氏黄丝藻生长的最适温度范围在15至20℃之间，藻细胞在5℃时生长缓慢，在30℃时无法存活。在20℃温度下最大生物量浓度为11.73 g/L，最高总脂质含量为干重的56.63%。低温未改变霍氏黄丝藻的脂肪酸谱，但促进了其不饱和脂肪酸的积累。棕榈油酸、二十碳五烯酸和总脂肪酸的最大含量分别为干重的23.64%、2.49%和41.14%。在三种温度（7、15、25℃）、两种氮浓度（3和18 mM）和两个培养时间（第3天和第12天）下进行了蛋白质组学分析。共鉴定出6503种蛋白质。在低温下，光合作用相关蛋白下调以保护光合机构。关键酶二酰甘油酰基转移酶（DGAT）和磷脂二酰甘油酰基转移酶（PDAT）的上调表明在低氮处理下三酰甘油（TAGs）的积累。霍氏黄丝藻中与核糖体、磷脂酰肌醇信号系统、抗氧化系统和冷休克蛋白（CSPs）相关的蛋白在低温处理下共同上调，这可以减轻温度胁迫诱导的损伤并维持藻细胞的正常生长和代谢。
霍氏黄丝藻是一种耐冷微藻。它是一种富含高含量棕榈油酸和一定量二十碳五烯酸的产油丝状微藻，在生物燃料开发以及营养保健品和其他行业的应用中具有巨大潜力。
