一株耐酸微藻的分离鉴定及其对锰离子胁迫的生理响应

【目的】探讨在酸性含锰极端水环境中油球藻的生长特性及其对环境pH和Mn^(2+)的影响。【方法】从某硫铁矿山的酸性废水库中分离获得纯化藻株,通过形态观察及18S r RNA基因测序对其进行鉴定,并着重考察了不同pH和典型金属离子Mn^(2+)浓度对其生长特性的影响,并通过测定藻生物量、光合色素、丙二醛(malondialdehyde,MDA)和还原型谷胱甘肽(reduced glutathione,GSH)含量以及超氧化物歧化酶(superoxide dismutase,SOD)、抗坏血酸过氧化物酶(ascorbate peroxidase,APX)比活力的变化,分析该藻对Mn^(2+)胁迫的生理响应机制。【结果】分离得到的藻株经鉴定为Graesiella sp.MA1;pH对该藻的生长有显著影响,其最低耐受初始pH为3.5;在初始pH为3.5和Mn^(2+)浓度分别为5、30和55 mg/L时,藻细胞生物量随着Mn^(2+)浓度的增加而下降,各试验组中的Mn^(2+)浓度亦分别降低了28.62%、21.90%和18.84%,且pH值分别升高至5.7、5.6、5.4,对照组pH则高达9.1;在培养24 d后,藻细胞叶绿素a/b值随Mn^(2+)浓度增加而下降,而MDA、GSH含量以及SOD、APX比活力则显著增加。结果表明,从酸性矿山废水库中分离纯化获得的油球藻能够同时耐受低pH和一定浓度范围内的Mn^(2+),在这种极端环境下,其细胞内的抗氧化系统缓减了膜脂质过氧化作用,从而在耐受重金属离子与解毒方面起到了重要作用。【结论】Graesiella sp.MA1具有耐受低pH、重金属离子以及产碱的作用,研究结果为利用油球藻开展酸性矿山废水原位生物修复提供了一定的理论依据。

Optimization of microwave pretreatment of lignocellulosic waste for enhancing methane production： Hyacinth as an example

The effect of microwave pretreatment on the anaerobic degradation of hyacinth was investigated using response surface methodology （RSM）. The components oflignin and the other constituents of hyacinth were altered by microwave pretreatment. Comparison of the near-infrared spectra of hyacinth pretreated by microwave irradiation and water-heating pretreatment revealed that no new compounds were generated during hyacinth pretreatment by microwave irradiation. Atomic force microscopy observations indicated that the physical structures of hyacinth were disrupted by microwave pretreatment. The yield of methane per gram of the microwave-irradiated substrate increased by 38.3% as compared to that of the substrate pretreated via water-heating. A maximum methane yield of 221 mL·g-sub^-1 was obtained under the optimum pretreatment conditions （substrate concentration （pSC） = 20.1 g·L^-1 and pretreatment time （PT） = 14.6 min） using RSM analysis. A maximum methane production rate of 0.76 mL·h^-1· g-sub^-1 was obtained by applying PSC = 9.5 g·L^-1 and PT= 11 min. Interactive item coefficient analysis showed that methane production was dependent on the PSC and PT, separately, whereas the interactive effect of the PSC and PT on methane production was not significant. The same trend was also observed for the methane production rate.