超声波对铜绿微囊藻超微结构和生理特性的影响

为了研究超声波对蓝藻细胞的影响，利用超声波（40W）处理200 mL铜绿微囊藻（Microcystis aeruginosa） 悬浮液20min，之后继续培养并于不同时间取样检测。检测悬浮藻细胞生物量发现其3d降低了97.84%；分别观察1、3、5d时沉降藻细胞超微结构变化，发现13d时细胞内脂质颗粒和藻青素颗粒增多、类囊体片层断裂、藻胆体脱落，5d时拟核区萎缩消失、细胞基础结构解体、胞质出现空洞、胞内结构颗粒降解；检测藻细胞光合放氧速率、叶绿素a （Chl.a）、超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性、膜透性以及跨膜ATP酶活性，发现光合放氧速率3d下降24.83%，Chl.a含量5d下降23.75%，超声组细胞SOD活性变化幅度比较大，但总体上活性降低，而CAT活性则表现为先增后减，活性始终大于对照组，同时胞内有机物渗出量增大，三种跨膜ATP酶活性（Na+/K+-ATPase、Mg2+-ATPase 和Ca2+-ATPase）均先升后降，并与膜透性变化相关。以上结果表明，超声波使铜绿微囊藻细胞沉降，并对其造成了胁迫，使部分藻细胞光合作用减弱，光合色素遭到损伤，细胞膜透性增大，甚至引起藻细胞程序性死亡。SOD活力的快速降低表明超声波使藻细胞内超氧离子（O2-）过量累积，从而对藻细胞造成氧化损伤，除此之外，超声波使藻细胞基础结构破坏、细胞内结构颗粒降解、细胞膜透性增大，这些都可能是致使部分铜绿微囊藻细胞死亡的重要原因。铜绿微囊藻细胞CAT以及跨膜ATP酶活性增大，表明藻细胞增强抗氧化酶活性以及离子调控和能量活动以抵御超声波的胁迫，而当胁迫随着时间减小后，细胞开始恢复生长和代谢，酶活力开始降低。  

EFFECTS OF ULTRASOND WAVE ON THE ULTRASTRUCTURE AND PHYSIOLOGICAL CHARACTERISTICS OF BLUE-GREEN ALGAE (MICROCYSTIS AERUGINOSA)

To study the effects of ultrasound wave on the blue-green algae (Microcystis aeruginosa), blue-green algae were exposed to ultrasound waves (40W) for 20 minutes, and then cultured for 1, 3, and 5 days. The results indicated that the biomass of suspended algae cells reduced by 97.84% at Day 3. From Day 1 to Day 3, lipid bodies and cyanophycin granules were accumulated, and thylakoid layers were cracked, and phycobilisomes attached to thylakoid dropped off in the cells. At Day 5, the nucleoid area gradually shrinked or disappeared, the cell infrastructure disintegrated, and voids appeared in cytoplasm and intracellular granules were degraded. Moreover, the photosynthetic oxygen evolution rate decreased by 24.83% on Day 3. Chl.a content reduced by 23.75% on Day 5. SOD activity and CAT activity were induced by ultrasound, although both of the activities diminished from Day1 to Day 5. The amount of intracellular organic exudation increased after treatment. The activities of three ATPases (Na+/K+-ATPase, Mg2+-ATPase and Ca2+-ATPase) increased firstly and then decreased, which was related to the change of membrane permeability. These results suggested that ultrasound wave may reduce algae photosynthesis, damage photosynthetic pigments and increase the membrane permeability, which can cause oxidative damage and induce death of M. aeruginosa. The dynamic CAT and ATPases activities suggested that M. aeruginosa may enhance antioxidant enzymes activity as well as ion regulation and energy activity to resist the ultrasound stress, and that the growth and metabolism of algae cells began to recover over time while the enzyme activities began to decline.