Yap Benjamin H J, Crawford Simon A, Dagastine Raymond R, Scales Peter J, Martin Gregory J O
Department of Chemical and Biomolecular Engineering, The University of Melbourne, Parkville, VIC, 3010, Australia.
School of Botany, The University of Melbourne, Parkville, VIC, 3010, Australia.
J Ind Microbiol Biotechnol. 2016 Dec;43(12):1671-1680. doi: 10.1007/s10295-016-1848-1. Epub 2016 Oct 24.
Nitrogen deprivation (N-deprivation) is a proven strategy for inducing triacylglyceride accumulation in microalgae. However, its effect on the physical properties of cells and subsequently on product recovery processes is relatively unknown. In this study, the effect of N-deprivation on the cell size, cell wall thickness, and mechanical strength of three microalgae was investigated. As determined by analysis of micrographs from transmission electron microscopy, the average cell size and cell wall thickness for N-deprived Nannochloropsis sp. and Chlorococcum sp. were ca. 25% greater than the N-replete cells, and 20 and 70% greater, respectively, for N-deprived Chlorella sp. The average Young's modulus of N-deprived Chlorococcum sp. cells was estimated using atomic force microscopy to be 775 kPa; 30% greater than the N-replete population. Although statistically significant, these microstructural changes did not appear to affect the overall susceptibility of cells to mechanical rupture by high pressure homogenisation. This is important as it suggests that subjecting these microalgae to nitrogen starvation to accumulate lipids does not adversely affect the recovery of intracellular lipids.
氮剥夺（N-剥夺）是诱导微藻中三酰甘油积累的一种已被证实的策略。然而，其对细胞物理性质以及随后对产物回收过程的影响相对未知。在本研究中，研究了氮剥夺对三种微藻的细胞大小、细胞壁厚度和机械强度的影响。通过透射电子显微镜图像分析确定，氮剥夺的微拟球藻属和绿球藻属的平均细胞大小和细胞壁厚度比氮充足的细胞大约25%，而氮剥夺的小球藻属的平均细胞大小和细胞壁厚度分别比氮充足的细胞大20%和70%。使用原子力显微镜估计，氮剥夺的绿球藻属细胞的平均杨氏模量为775 kPa，比氮充足的群体高30%。尽管这些微观结构变化具有统计学意义，但它们似乎并未影响细胞对高压均质化机械破裂的总体敏感性。这很重要，因为这表明使这些微藻经历氮饥饿以积累脂质不会对细胞内脂质的回收产生不利影响。
