Xinjiang Key Laboratory of Environmental Pollution and Bioremediation, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China; Graduate University of Chinese Academy of Sciences, Beijing, 100049, China.
Xinjiang Key Laboratory of Environmental Pollution and Bioremediation, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China.
Water Res. 2015 Feb 1;69:51-58. doi: 10.1016/j.watres.2014.10.060. Epub 2014 Nov 13.
H2O2 is an emerging biocide for bloom-forming cyanobacteria. It is important to investigate the H2O2 scavenging ability of extracellular polymeric substances (EPS) of cyanobacteria because EPS with strong antioxidant activity may "waste" considerable amounts of H2O2 before it kills the cells. In this study, the buffering capacity against H2O2 of EPS from the bloom-forming cyanobacterium Microcystis aeruginosa was investigated. IC50 values for the ability of EPS and vitamin C (VC) to scavenge 50% of the initial H2O2 concentration were 0.097 and 0.28 mg mL(-1), respectively, indicating the higher H2O2 scavenging activity of EPS than VC. Both proteins and polysaccharides are significantly decomposed by H2O2 and the polysaccharides were more readily decomposed than proteins. H2O2 consumed by the EPS accounted for 50% of the total amount of H2O2 consumed by the cells. Cell growth and photosynthesis were reduced more for EPS-free cells than EPS coated cells when the cells were treated with 0.1 or 0.2 mg mL(-1) H2O2, and the maximum photochemical efficiency Fv/Fm of EPS coated cells recovered to higher values than EPS-free cells. Concentrations of H2O2 above 0.3 mg mL(-1) completely inhibited photosynthesis and no recovery was observed for both EPS-free and EPS coated cells. This shows that EPS has some buffering capacity against the killing effect of H2O2 on cyanobacterial cells. Such a strong H2O2 scavenging ability of EPS is not favorable for killing bloom-forming cyanobacteria. The high H2O2 scavenging capacity means considerable amounts of H2O2 have to be used to break through the EPS barrier before H2O2 exerts any killing effects on the cells. It is therefore necessary to determine the H2O2 scavenging capacity of the EPS of various bloom-forming cyanobacteria so that the cost-effective amount of H2O2 needed to be used for killing the cyanobacteria can be estimated.
H2O2 是一种新兴的杀藻剂，可用于杀灭蓝藻水华。研究蓝藻细胞外聚合物（EPS）对 H2O2 的清除能力非常重要，因为具有较强抗氧化活性的 EPS 可能会在杀死细胞之前“浪费”大量的 H2O2。本研究考察了铜绿微囊藻形成水华的 EPS 对 H2O2 的缓冲能力。EPS 和维生素 C（VC）清除 50%初始 H2O2 浓度的能力的 IC50 值分别为 0.097 和 0.28 mg mL(-1)，表明 EPS 对 H2O2 的清除活性高于 VC。H2O2 可显著分解蛋白质和多糖，且多糖比蛋白质更易分解。EPS 消耗的 H2O2 占细胞消耗 H2O2 总量的 50%。当用 0.1 或 0.2 mg mL(-1) H2O2 处理细胞时，无 EPS 细胞的生长和光合作用比包被 EPS 细胞的生长和光合作用减少更多，且包被 EPS 细胞的最大光化学效率 Fv/Fm 恢复到比无 EPS 细胞更高的值。当 H2O2 浓度高于 0.3 mg mL(-1)时，光合作用完全受到抑制，无 EPS 细胞和包被 EPS 细胞均未观察到恢复。这表明 EPS 对 H2O2 杀灭蓝藻细胞的效应具有一定的缓冲能力。EPS 对 H2O2 具有很强的清除能力，不利于杀灭形成水华的蓝藻。这种高的 H2O2 清除能力意味着需要使用大量的 H2O2 来突破 EPS 屏障，然后 H2O2 才能对细胞发挥任何杀伤作用。因此，有必要确定各种形成水华的蓝藻的 EPS 的 H2O2 清除能力，以便估算出用于杀灭蓝藻的具有成本效益的 H2O2 量。
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