Biochemical characterization of Rhodomonas sp. Hf-1 strain (cryptophyte) under nitrogen starvation
Biochemical characterization of Rhodomonas sp. Hf-1 strain (cryptophyte) under nitrogen starvation
复制标题
红单胞菌属的生化特征。
DOI：
10.1016/j.aquaculture.2019.734648
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发表时间：
2020
期刊：
影响因子：
4.5
通讯作者：
Yoshimatsu T.
中科院分区：
文献类型：
--
作者：
Yamamoto S.;Bossier P.;Yoshimatsu T.
Rhodomonassp. Hf-1菌株（隐藻）是水产养殖中某些海洋动物的优良饲料。在这项研究中，Hf-1菌株培养在不同的氮浓度下，以评估其生长和生化特征的N-饥饿条件的影响。将0.9 mM（低N）和3.5 mM（高N）的两种硝酸盐浓度补充到培养基中。在第3天和第7天对细胞悬浮液取样，并分析光合色素、蛋白质和相对脂肪酸含量。低氮和高氮培养中的硝酸盐分别在第3天和第7天耗尽，低氮培养中的生长显著低于高氮培养。藻红蛋白（PE）含量下降，在两种文化相比，叶绿素（Chl）aandc，和细胞颜色的变化，只观察到在低氮培养，表明PE优先降解相比，叶绿素（Chl）aandc在培养基中的氮是有限的。在两种培养基中培养的Hf-1细胞中的细胞间碳和氢含量在整个实验中显示出类似的变化，因此C/H比在两者之间没有差异。另一方面，用高N培养基培养的Hf-1细胞中的细胞间氮含量从第3-7天从5.6%增加到10.3%。而低氮培养则表现出氮含量从8.1%下降到4.1%。因此，低氮和高氮培养的C/N比表现出完全不同的变化趋势。同样，在用高N培养基培养的Hf-1细胞中的蛋白质含量在4天期间增加。与此相反，低氮培养显示蛋白质含量下降了30%。通过实验发现，Hf-1细胞中脂肪酸的相对含量在低氮培养中低于高氮培养。低氮培养第3天的主要脂肪酸为多不饱和脂肪酸（PUFA），占总脂肪酸的37.4%。但到实验结束时，PUFA的相对含量下降到总脂肪酸的24.7%，且优势脂肪酸向饱和脂肪酸（SFA）转移。这些数据表明，氮饥饿在培养基中诱导的蛋白质和相对脂肪酸含量的同时减少与细胞的颜色变化的Hf-1细胞，这表明这种行为的细胞颜色变化的可能性，可以作为一个有效的指标，以确定收获时间ofRhodomonasspecies视觉。
Rhodomonassp. Hf-1 strain (cryptophyte) has been known as an excellent feed for some marine animals in aquaculture. In this study, the Hf-1 strain was cultured under different nitrogen concentrations to evaluate the effect of N-starved conditions on its growth and biochemical profile. Two nitrate concentrations of 0.9 mM (Low-N) and 3.5 mM (High-N) were supplemented to the media. The cell suspensions were sampled on day 3 and 7 and analyzed for photosynthesis pigments, protein and relative fatty acids contents. The nitrate in Low-N and High-N cultures was exhausted by day 3 and 7, respectively, and growth in Low-N culture was significantly lower than in High-N culture. Phycoerythrin (PE) content decreased in both cultures compared to chlorophyll (Chl)aandc, and a cell-color change was only observed in Low-N culture, indicating that PE was preferentially degraded compared with Chlaandcwhen nitrogen in the medium was limiting. The intercellular carbon and hydrogen content in the Hf-1 cells cultured in both media showed similar changes throughout the experiment, hence C/H ratios did not differ in between. On the other hand, the intercellular nitrogen content in the Hf-1 cells cultured with High-N medium increased from 5.6 to 10.3% from day 3–7. However, Low-N culture showed a decrease in nitrogen content from 8.1 to 4.1%. Consequently, C/N ratio in Low-N and High-N culture showed entirely different tendency. Similarly, the protein content in the Hf-1 cell cultured with High-N medium increased during 4 days. In contrast, Low-N culture showed a decrease by 30% in protein content. Relative fatty acids content in the Hf-1 cell was lower in Low-N culture than High-N culture through the experiment. The dominant fatty acids in Low-N culture were poly-unsaturated fatty acids (PUFA) on day 3, which accounted for 37.4% of total fatty acid. However, the relative content of PUFA reduced to 24.7% of total fatty acid by the end of the experiment, and the dominant fatty acids shifted to saturated fatty acids (SFA). These data indicate that nitrogen starvation in the medium induced a simultaneous decrease in protein and relative fatty acids contents with the cell-color change for the Hf-1 cell, suggesting the possibility that this behavior on the cell-color change can be used as a valid indicator to determine the harvest timing ofRhodomonasspecies visually.