低温处理对段殖黄线藻生长、油脂积累、光合及抗氧化酶活性的影响

LOW TEMPERATURE TREATMENT ON THE GROWTH, OIL ACCUMULATION, PHOTOSYNTHESIS, AND ANTIOXIDANT ENZYME ACTIVITY OF XANTHONEMA HORMIDIOIDES

  • 摘要: 以丝状产油微藻段殖黄线藻(Xanthonema hormidioides)作为实验材料, 经过低温(5℃)预处理后的藻种与常温(25℃)条件下的藻种进行对比实验, 研究段殖黄线藻在不同温度(5℃、10℃、15℃、20℃、25℃)和高、低氮浓度(18 和3 mmol/L)条件下的生长和油脂积累及低温(5℃)对这两种状态下的藻种光合活性和抗氧化酶系统的影响。结果显示: 低温预处理后的段殖黄线藻在各温度下积累的生物量要高于常温条件下的段殖黄线藻, 在15℃时可达到最高生物量为10.1 g/L, 20℃条件下可获得最高油脂和脂肪酸绝对含量, 分别占干重的64.20%和49.05% (3 mmol/L), 蛋白质含量在15℃时达到最高为43.5% (18 mmol/L), 总碳水化合物则基本维持在10%—25%。5℃下段殖黄线藻对光的利用率(α)及最大电子传递速率(ETRmax)均受到明显抑制, 低温预处理后的段殖黄线藻叶绿素a含量、Fv/FmFv/Fo值均在第9天后超过常温实验组, 最高分别可达9.98 mg/g、2.99和0.75 (3 mmol/L)。与常温实验组相反, 低温预处理后段殖黄线藻在5℃下ETRmax和对强光的耐受能力(IK)均有所升高。此外, 低温预处理后段殖黄线藻超氧化物歧化酶(SOD)和过氧化氢酶(CAT)的最大活性可达65.6和0.56 U/mg protein, 均显著高于常温段殖黄线藻(P<0.05)。综上, 低温预处理后的段殖黄线藻生长和代谢产物的积累更具优势, 并且在低温适应性、光合效率及抗氧化应激方面的能力也得到显著提升。

     

    Abstract: The filamentous oleaginous microalga Xanthonema hormidioides was used as the experimental material, and a control experiment was carried out between the low-temperature (5℃) treated algal inoculum and the room-temperature (25℃) algal inoculum. We examined the physiological and biochemical indexes of the two treated inocula at different temperatures (5℃, 10℃, 15℃, 20℃, 25℃) and under two nitrogen concentrations (18 and 3 mmol/L). Additionally, we explored the impact of low temperature (5℃) on the photosynthetic activity and antioxidant enzyme system of the two algal inoculum. The results showed that the biomass of Xanthonema hormidioides subjected to low-temperature treatment surpassed that of the room-temperature algal inoculum at all temperatures, with the highest biomass of 10.1 g/L recorded at 15℃. The highest content of lipid and fatty acids was obtained at 20℃, accounting for 64.20% and 49.05% of dry weight, respectively (3 mmol/L). The protein content peaked at 15℃, reaching 43.5% (18 mmol/L), while total carbohydrates levels remained relatively consistent, ranging between 10% and 25%. At 5℃, the utilization efficiency of light (α) and the maximum electron transfer rate (ETRmax) of Xanthonema hormidioides from the room temperature were significantly inhibited. The chlorophyll a content, Fv/Fm, and Fv/Fo values of low-temperature treated Xanthonema hormidioides were higher than those of the room temperature experimental group from the 9th day, with the highest values reaching 9.98 mg/g, 2.99, and 0.75 (3 mmol/L), respectively. In contrast to the room temperature experimental group, the ETRmax and tolerance to strong light (IK) were enhanced in Xanthonema hormidioides to low-temperature treatment at 5℃. In addition, the maximum activities of superoxide dismutase (SOD) and catalase (CAT) in Xanthonema hormidioides under low temperature treatment reached 65.6 and 0.56 U/mg protein, respectively, significantly surpassing the values of Xanthonema hormidioides at normal temperature (P<0.05). The results indicate that low temperature treatment is more conducive to the growth and metabolites accumulation of Xanthonema hormidioides, and the adaptability to low temperature, photosynthetic efficiency, and resistance to oxidative stress.

     

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