一株酸性红壤拟小球藻的分离及其镉吸附能力研究

Isolation of a Novel Parachlorella sp.from Acid Rice Paddy Soil and Its Cadmium Adsorption Capacity

华南红壤稻田同时受到酸化和镉(Cd)污染的胁迫,以藻类为代表的生物材料可同时提升环境pH和吸附Cd,因此,将藻类用于Cd污染酸性土壤修复的研究备受关注.本研究从华南酸性水稻土壤中筛选得到一株具备耐酸耐Cd能力的微藻,通过形态观察和18S rRNA基因序列测序以及系统发育树分析,被鉴定为拟小球藻,最终将其命名为ZJ1(Parachlorella sp.ZJ1).藻株ZJ1的耐酸、耐Cd实验结果表明,其能耐受的最低pH为3.50,能耐受的最高Cd浓度为6.00 mg/L.藻株ZJ1的Cd吸附能力实验结果表明,在pH=6.00以及初始Cd浓度分别为1.50、3.00和5.00 mg/L的条件下,藻株ZJ1对Cd的吸附率分别为67.36%、64.89%和41.03%.吸附动力学拟合结果表明,藻株ZJ1对Cd的吸附特征符合二级动力学模型和Langmuir等温吸附模型,属于化学吸附和单分子层吸附.当pH=4.00、初始Cd浓度为3.00 mg/L时,藻株ZJ1对Cd的去除率能够达到56.81%,并且能将体系pH提升至6.50左右,表明藻株ZJ1具备在酸性环境下吸附Cd并提升体系pH的能力.藻株ZJ1的获得,有望为应对华南红壤稻田土壤酸化和Cd污染的双重胁迫提供理论支持的同时,提供可再生的生物修复功能材料.

Red soil paddy fields in southern China are under stress from both acidification and cadmium(Cd)contamination.The use of microalgae to remediate Cd-contaminated acidic soils has received extensive attention because they can simultaneously increase soil pH and adsorb Cd.In this study,an acid-and Cd-tolerant microalgae was screened from acidic rice soils in southern China and identified as Parachlorella sp.ZJ1 by morphological observation,18S rRNA gene sequencing and phylogenetic tree analysis.The lowest pH and the highest Cd concentration that ZJ1 could tolerate were 3.50 and 6.00 mg/L,respectively.The experimental results showed that the Cd adsorption capacity of ZJ1 strain was 67.36%,64.89%and 41.03%under the conditions of pH=6.00 and initial Cd concentrations of 1.50,3.00 and 5.00 mg/L,respectively.The fitting results of adsorption kinetics showed that the adsorption of Cd by ZJ1 was consistent with the second-order kinetic model and Langmuir model,which belonged to chemisorption and monolayer adsorption.When the pH=4.00 and the initial Cd concentration was 3.00 mg/L,the adsorption rate of Cd by algae strain ZJ1 was about 56.81%,and the pH value of the system could be raised to about 6.50,which indicated that ZJ1 had the ability to adsorb Cd in acidic environment and improve the pH value of the system.The acquisition of the algal strain ZJ1 can provide a strain resource and theoretical basis for the remediation of acidic Cdcontaminated soils.