Microalgae such as Chlamydomonas reinhardtii accumulate triacylglycerol (TAG), which is a potential source of biofuels, under stress conditions such as nitrogen deprivation, whereas Chlamydomonas debaryana NIES-2212 has previously been identified and characterized as one of the rare species of Chlamydomonas, which massively accumulates TAG in the stationary phase without external stress. As the high density of the cells in the stationary phase was supposed to act as a trigger for the accumulation of TAG in C. debaryana, in this study, C. debaryana was encapsulated in a Ca2+-alginate gel for the culture with high cell density. We discovered that the growth of the encapsulated cells resulted in the formation of spherical palmelloid colonies with high cell density, where daughter cells with truncated flagella remained wrapped within the mother cell walls. Interestingly, gel encapsulation markedly promoted proliferation of C. debaryana cells, and the encapsulated cells reached the stationary phase earlier than that of the free-living cells. Gel encapsulation also enhanced TAG accumulation. Gene expression analysis revealed that two genes of acyltransferases, DGAT1 and DGTT3, were upregulated in the stationary phase of free-living C. debaryana. In addition, the gene expression of these acyltransferases increased earlier in the encapsulated cells than that in the free-living cells. The enhanced production of TAG by alginate gel encapsulation was not found in C. reinhardtii which is known to use a different repertoire of acyltransferases in lipid accumulation.

中文翻译：

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通过凝胶包裹衣原体NIES-2212的脂质包裹形成具有增强脂质积累的球形棕榈果体集落。

微藻（例如莱茵衣藻）在压力条件下（例如氮剥夺）下积累了三酰基甘油（TAG），这是一种潜在的生物燃料来源，而之前已鉴定出debaryana NIES-2212衣藻并被定性为衣藻中的一种稀有物种，该物种大量存在TAG在固定相中积累而没有外部应力。由于固定相中的高密度细胞被认为是TAG在C.debaryana中积累的诱因，因此在本研究中，将C. debaryana封装在Ca2 +-海藻酸盐凝胶中以进行高细胞密度的培养。我们发现被囊化细胞的生长导致形成具有高细胞密度的球形棕榈节菌落，截短鞭毛的子细胞仍包裹在母细胞壁中。有趣的是，凝胶封装显着促进了C. debaryana细胞的增殖，并且封装的细胞比自由活动的细胞更早地到达固定相。凝胶封装还增强了TAG的积累。基因表达分析表明，酰基转移酶的两个基因DGAT1和DGTT3在自由生活的C. debaryana的固定期上调。另外，这些酰基转移酶的基因表达在包封的细胞中比在自由生活的细胞中更早地表达。通过藻酸盐凝胶封装增强TAG的产量未在莱茵衣藻中发现，该衣藻已知在脂质积累中使用不同的酰基转移酶库。凝胶封装显着促进了C. debaryana细胞的增殖，并且封装的细胞比自由活动的细胞更早地到达固定相。凝胶封装还增强了TAG的积累。基因表达分析表明，酰基转移酶的两个基因DGAT1和DGTT3在自由生活的C. debaryana的固定期上调。另外，这些酰基转移酶的基因表达在包封的细胞中比在自由生活的细胞中更早地表达。通过藻酸盐凝胶封装增强TAG的产量未在莱茵衣藻中发现，该衣藻已知在脂质积累中使用不同的酰基转移酶库。凝胶封装显着促进了C. debaryana细胞的增殖，并且封装的细胞比自由活动的细胞更早地到达固定相。凝胶封装还增强了TAG的积累。基因表达分析表明，酰基转移酶的两个基因DGAT1和DGTT3在自由生活的C. debaryana的固定期上调。另外，这些酰基转移酶的基因表达在包封的细胞中比在自由生活的细胞中更早地表达。通过藻酸盐凝胶封装增强TAG的产量未在莱茵衣藻中发现，该衣藻已知在脂质积累中使用不同的酰基转移酶库。凝胶封装还增强了TAG的积累。基因表达分析表明，酰基转移酶的两个基因DGAT1和DGTT3在自由生活的C. debaryana的固定期上调。另外，这些酰基转移酶的基因表达在包封的细胞中比在自由生活的细胞中更早地表达。通过藻酸盐凝胶封装增强TAG的产量并未在莱茵衣藻中发现，该衣藻已知在脂类积累中使用不同的酰基转移酶库。凝胶封装还增强了TAG的积累。基因表达分析表明，酰基转移酶的两个基因DGAT1和DGTT3在自由生活的C. debaryana的固定期上调。另外，这些酰基转移酶的基因表达在包封的细胞中比在自由生活的细胞中更早地表达。通过藻酸盐凝胶封装增强TAG的产量未在莱茵衣藻中发现，该衣藻已知在脂质积累中使用不同的酰基转移酶库。