NaNO_3胁迫对两种微囊藻VOCs释放的影响

THE EFFECTS OF NaNO_3 STRESS ON THE RELEASE OF VOCs FROM TWO MICROCYSTIS

为了揭示硝酸盐过量积累对藻类产生胁迫后对藻类挥发性有机化合物(VOCs)释放以及水体气味的影响,研究以形成蓝藻水华的主要种类铜绿微囊藻和水华微囊藻为材料,在Na NO3胁迫下,对其细胞生长和释放的VOCs进行测定分析。结果表明,Na NO3胁迫24h后,铜绿微囊藻和水华微囊藻细胞生长均受到明显影响,与对照相比细胞密度分别降低了29.6%和43.0%。在正常条件下,铜绿微囊藻和水华微囊藻分别释放出26和27种化合物,其主要类型是硫化物、烃类、萜烯类、苯类、醛类和酯类化合物。在Na NO3胁迫下,VOCs含量均明显增加,其中铜绿微囊藻释放的此6类VOCs含量分别增加了60.5%、14.3%、136.6%、92.1%、730.0%和120.7%,水华微囊分别增加了172.7%、162.5%、154.0%、55.9%、51.2%和109.4%。此外,铜绿微囊藻VOCs中出现4种新成分,水华微囊藻VOCs中出现1种新成分。由此可见,硝酸盐过量积累对藻细胞产生胁迫后会诱导其释放出大量VOCs,从而增加水体气味、破坏水质。

Nitrate is one of the major sources of pollution in water bodies. To reveal how the excessive nitrate accumulation affects the release of VOCs and causes the odor in the water, we analyzed the cell growth and VOCs from Microcystis aeruginosa and M. flosaquae--the primary species responsible for the cyanobacterial bloom--under the NaNO3 stress. Compared to the control NaNO3 significantly reduced the cell growth of M. aeruginosa and M. flos-aquae by 29.6% and 43.0% respectively after the 24 h stress. Under the normal condition, M. aeruginosa and M. flosaquae released 26 and 27 compounds respectively, and the major types of VOCs were sulphide, hydrocarbons, terpenoids, benzenes, aldehydes and esters. In M. aeruginosa the release of these 6 VOCs was remarkably increased by 60.5%, 14.3%, 136.6%, 92.1%, 730.0% and 120.7% respectively after the NaNO3 treatment, and the increments in M. flos-aquae were 172.7%, 162.5%, 154.0%, 55.9%, 51.2% and 109.4% respectively. In addition, 4 new compounds were found in VOCs of M. aeruginosa under the NaNO3 stress, and 1 new compound was found in VOCs of M. flosaquae. Therefore, the stress of excessive nitrate accumulation on algae may promote the release of VOCs, which could aggravate the odor and the quality of the water.