耐性真菌HA吸附铅、锌的影响因素及吸附机理研

【目的】从铅锌矿区分离筛选出耐铅锌性菌株,并研究其吸附铅、锌的影响因素及吸附机理,为重金属污染微生物修复提供参考。【方法】以从铅锌矿区筛选出的耐铅锌真菌HA作为试验菌株,考察影响其对铅、锌去除能力的主要因素(初始浓度、pH、接种量),同时通过等温吸附模型、动力学分析及红外光谱分析探讨其相关的吸附机理。【结果】经鉴定,从矿区筛选的对Pb2+、Zn2+有较强耐性的菌株HA为米曲霉(Aspergillus oryzae);在初始铅、锌浓度的实验范围内(100-800mg/L),HA对铅、锌离子的去除率随着其初始浓度增加而减小,25h后HA的生长进入平稳期,且对铅、锌离子的去除率趋于稳定。当铅、锌初始浓度为100mg/L、pH为5.0时,HA对铅、锌离子的去除率均达到最高,分别为97.8%、54.1%;当HA接种量为1mL时,其对铅、锌去除率的增长率达到最大。HA对铅、锌的吸附过程满足Langmuir吸附模型,其吸附以单层吸附为主。在动态吸附过程中,HA对Pb2+、Zn2+离子吸附性能与准二级动力学吸附方程的拟合程度更高,且对Pb2+的吸附效果明显高于Zn2+。红外光谱分析表明,HA细胞中羟基、烷基、酰胺基、羰基、磷酸基等参与了Pb2+、Zn2+的吸附过程。【结论】HA是一株对铅、锌有较强吸附能力的真菌,其吸附铅、锌影响因素及吸附机理研究结果将为重金属污染微生物修复提供指导。     

乌鲁木齐市道路林带土壤抗重金属细菌的筛选及重金属去除能力

【背景】道路重金属污染问题日益严峻,寻找高效的微生物资源用于环境修复已迫在眉睫。【目的】从乌鲁木齐市道路林带土壤中筛选抗重金属菌株,并对其重金属去除能力进行探究。【方法】使用含5种重金属离子(铅、镉、锌、铜、镍)的4种培养基进行抗性菌株筛选,通过形态学特征和16S rRNA基因序列进行鉴定,采用电感耦合等离子体发射光谱仪(inductively coupled plasma optical emission spectrometer,ICP-OES)检测分离株对重金属离子的去除情况。【结果】4种分离培养基中,TSA是抗重金属菌株筛选的最适培养基,共筛选出16株抗重金属菌,其中4株抗Pb菌、4株抗Cd菌、4株抗Zn菌、3株抗Cu菌和1株抗Ni菌,其抗性分别高达3 000、800、600、300和400mg/L,16株菌中以芽孢杆菌属(Bacillus)数量最多。在初始浓度为700mg/L Pb²⁺下,菌株Pb6的去除率高达92.48%,菌株Pb11、Pb3和Pb9的去除率分别为27.70%、40.37%和58.88%;在200mg/L Cd²⁺...     

抗铅锌功能菌生长菌株和干菌体吸附Pb2+、Zn2+性能优化及机理分析

【目的】针对湖南资兴铅锌矿污染问题,筛选本土耐性菌株用作生物修复。【方法】供试菌株J3筛选自湖南资兴铅锌矿区的尾砂矿矿渣,利用正交实验分析其生长菌株及干菌体最佳吸附条件以优化其吸附效果,同时对相关数据进行动力学拟合以探讨其吸附机理,最后结合形态观察和18S rRNA基因序列分析对其进行分类鉴定。【结果】在最佳条件下,J3生长菌株对Pb2+和Zn2+的去除率分别为92.2%和87.7%;干菌体对Pb2+和Zn2+去除率分别为72.6%和23.8%,反应动力学模型研究表明,生长菌株吸附过程中吸附速率受重金属浓度影响,对Zn2+吸附主要为颗粒内扩散作用;干菌体对Pb2+吸附推测为膜扩散和颗粒内扩散作用,而对Zn2+的吸附则由膜扩散控制。根据形态特征和系统发育分析,J3初步鉴定为虫生轮枝菌。【结论】生长菌株吸附效果好于干菌体,二级动力学方程拟合结果可为生物吸附反应器的设计提供理论参考和实践指导。     

一株具有植物促生作用的重金属铅吸附菌的筛选与鉴定

【背景】随着工业化的发展,重金属污染逐渐成为主要的环境污染之一。微生物修复去除重金属污染成为近些年来新兴的修复方法,筛选开发具有良好修复功能的微生物菌株具有重要的现实意义。【目的】筛选具有促进植物生长作用的重金属修复菌株,为生物修复和植物促生等综合开发利用提供微生物资源。【方法】利用选择性培养基从淤泥中筛选重金属铅的抗性菌株,根据形态学观察、生理生化鉴定和16S rRNA基因序列分析对菌株进行分离鉴定,通过单因素分析不同培养条件对菌株生长的影响;采用原子吸收光谱法、比色法及平板对峙法等对菌株的重金属铅吸附率、无机磷溶解能力、吲哚乙酸(indole-3-acetic acid,IAA)分泌及拮抗镰刀菌效果等进行分析。【结果】从污染严重的塘泥中筛选到一株对重金属铅有较好吸附率的菌株,在150 mg/L Pb²⁺浓度下,对Pb²⁺的吸附率达90%以上;初步鉴定该菌株为蜡样芽孢杆菌,命名为SEM-15;菌株还具有较好的溶解无机磷、分泌IAA及拮抗镰刀菌的能力;菌株生长适应性强,可以在pH 10.0的强碱性环境下生长,该菌株具有很好的重金属铅污染修复及促生防病的应用潜力。【结论】菌株SEM-15是一株具有植物促生作用的重金属铅吸附菌株,在重金属污染土壤联合植物修复的应用中可能具有较好的开发价值。     

三株耐铅锌菌的分离、鉴定及其吸附能力

以铅锌矿渣盆栽试验中长势较好的耐性植物夹竹桃(Nerium indicum)的根际土壤为材料,进行耐铅锌优势菌株的分离鉴定,探讨影响铅锌吸附的因素及其吸附机理。结果表明:(1)从土样中分离筛选出3株耐铅锌菌株(B1、B4、B14),3株菌均能在Pb2+、Zn2+浓度为600 mg·L-1的牛肉膏蛋白胨培养基上生长,经形态和分子生物学鉴定分别为蜡样芽孢杆菌(Bacillus cereus)或炭疽杆菌(Bacillus anthracis)、解硫胺素硫胺素芽孢杆菌(Aneurinibacillus aneurinilyticus)和藤黄微球菌(Micrococcus luteus)。(2)对影响菌株吸附铅、锌的p H、吸附时间、初始菌量3个因素进行分析,发现菌株B1在p H为5.0、吸附时间为50 min、初始菌量为0.06 g时,对Pb2+、Zn2+的去除率分别可达84.22%和70.66%。菌株B4在p H为6.0、吸附时间为50 min、初始菌量为0.18 g时,对Pb2+、Zn2+的去除率分别可达72.63%和54.17%。菌株B14在p H为4.0、吸附时间为60 min、初始菌量为0.10 g时对Pb2+、Zn2+的吸附率分别为77.56%和50.63%。(3)扫描电镜观察和红外光谱分析显示:3株菌对Pb2+、Zn2+的吸附主要是细胞表面的吸附,还存在一定的内部吸收;羟基(O-H)、胺基(N-H)、烷基、酰胺基(CONH-)是吸附、络合或螯合金属离子或原子的主要活性基团,重金属与菌株表面的活性基团结合反应是其吸附Pb2+、Zn2+的主要作用机制。     

出芽短梗霉菌JB16铅镉吸附特性的研究北大核心

【目的】本文对污染土壤中的耐重金属菌株进行分离鉴定,研究菌株在不同条件下对吸附铅镉的影响因素。【方法】通过生理生化特征及ITS序列分析确定菌株种属,采用平板划线法确定最大耐铅镉浓度并探究菌株吸附的最佳条件;通过准二级动力学、Langmuir和Freundlich等温吸附的模型及红外光谱探究吸附过程。【结果】菌落形态和ITS序列分析鉴定表明,筛选分离的JB16为出芽短梗霉菌(Aureobasidium pullulans),最大耐铅浓度达1500 mg/L,最大耐镉浓度达750 mg/L,最大耐铅镉混合浓度达1500 mg/L和300 mg/L。通过单因素实验(温度、时间、菌龄、pH、湿菌体浓度和初始重金属浓度)得出结论,在温度30℃、时间2 h、菌龄72 h、pH 6、湿菌体浓度5 g/L和初始铅浓度150 mg/L的最佳条件下,菌体对铅的吸附率为88.5%;在温度30℃、时间1 h、菌龄96 h、pH 6、湿菌体浓度5 g/L和初始镉浓度20 mg/L的最佳条件下,菌体对镉的吸附率为59.4%。菌株吸附铅镉过程符合Langmuir吸附模型和准二级动力学模型,为表面单分子层吸附。扫描电镜和红外光谱分析表明,重金属离子对菌体造成影响,吸附前后形态发生变化,细胞表面的羟基、羧基、饱和C−H键和酰胺基等基团参与了吸附过程。【结论】菌株JB16具有一定的铅镉吸附效果,为修复重金属铅镉污染的水体和土壤提供宝贵的菌种资源和数据支持。     

蜈蚣草耐铅、铜、锌毒性和修复能力的研究

重金属复合污染是主要土壤污染类型之一。为了探明蜈蚣草修复土壤重金属复合污染的能力,土培试验研究了分别添加不同浓度铅、铜、锌条件下蜈蚣草生物量变化,结果表明,不同浓度铅和较低浓度锌处理下蜈蚣草生物量呈显著性地增加,土壤Pb、Zn添加浓度分别为1750mg／kg和1350mg／kg,蜈蚣草生物量最大。说明蜈蚣草有极强的耐Pb、Zn毒性能力,能在较高有效态Pb或Zn污染土壤上正常生长。蜈蚣草具有一定的耐Cu毒性能力,在Cu耐性方面,蜈蚣草可能存在生态型的差异。以上结果说明,利用蜈蚣草修复萃取Pb—As,Zn—As,Cu-As等复合污染土壤上As有重要的意义。     

鄱阳湖-乐安河段湿地耐Cu、Zn、Pb植物促生菌的分离、筛选及鉴定

【背景】植物促生菌因其对植物生长促进及增强抗逆性等优点在植物-微生物联合修复重金属污染土壤中具有良好应用潜力。在污染土壤中,土著植物促生菌能够更好地定殖并保证促植物生长能力的发挥。【目的】从常年受上游多种重金属污染的鄱阳湖-乐安河段湿地分离出一批具有多种重金属抗性的优势土著植物促生菌,以期为植物-微生物联合修复重金属污染湿地提供一批优质的菌种资源。【方法】从乐安河流域戴村受重金属污染的湿地土壤及水体中分离具有Cu、Zn、Pb抗性菌株,测定菌株的促植物生长特性[产IAA(Indole acetic acid)、溶磷、产铁载体及ACC(1-Aminocyclopropane-1-carboxylic acid)脱氨酶活性],挑选促生特性较好的菌株进行16S r RNA基因序列分析鉴定,并测定菌株对其他胁迫条件(抗生素、酸碱、盐)的耐受能力。【结果】分离得到22株能够同时耐受Cu 50 mg/L、Zn 400 mg/L、Pb 800 mg/L的菌株,其中10株表现出较好的促植物生长特性,对其进行16S r RNA基因序列分析鉴定,有4株属于Ralstonia sp.,3株属于Burkholderia sp.,另3株则分别属于Cupriavidus sp.、Stenotrophomonas sp.和Novosphingobium sp.。基于这10株菌抗性特征的聚类分析及主成分分析,结果与系统发育树分析结果高度一致。【结论】耐受多种重金属的土著植物促生菌的分离鉴定为重金属污染土壤的植物-微生物联合原位修复提供良好的微生物资源。     

铅镉抗性菌株JB11强化植物对污染土壤中铅镉的吸收

研究了铅、镉抗性菌株(JB11)和生物降解螯合剂乙二胺二琥珀酸(S,S)-EDDS)提高高羊茅和红三叶草吸收土壤中铅、镉的能力。从土壤样品中筛选出1株对Cd、Pb具有较强抗性的菌株JB11,经鉴定为成团泛菌属(Pantoea agglomerans)。JB11对Pb2+、Cd2+、Cr6+、Cu2+、Zn2+、Ni2+等多种重金属和卡那霉素、氨苄青霉素、链霉素、四环素等抗生素具有抗性,在温度15—35℃和pH为5.0—9.0范围内生长良好,最适生长温度为30℃,最适pH值为7.0左右,在低于3%的NaCl浓度下生长良好。盆栽试验研究了菌株JB11、EDDS及1/2EDDS+JB11 3种处理下对生长在Cd 100 mg/kg、Cd 200 mg/kg、Pb 500 mg/kg和Pb 1000mg/kg的土壤中的高羊茅和红三叶生长及从土壤富集Cd、Pb能力的影响。结果表明,外加JB11能使高羊茅和红三叶的干重分别比对照都有增加。除外加JB11后在经Pb 1000 mg/kg处理的土壤中高羊茅地上部的Pb浓度、经Cd 200 mg/kg处理的土壤中红三叶地上部的Cd浓度以及经Cd 100 mg/kg处理的土壤中高羊茅和红三叶根部的Cd浓度以外,外加JB11后对其他重金属处理植物中Pb和Cd的含量都显著增加。外加EDDS后除在经Pb 500 mg/kg的土壤中高羊茅根部的Pb浓度增加差异不显著,对其余重金属处理都可产生显著的影响(P0.05)。1/2EDDS+JB11的复合处理下植物重金属吸收量多数高于JB11和EDDS单独处理,JB11用于植物修复土壤Pb和Cd污染具有很大的潜力。     

一株耐铅镉真菌的分离鉴定及其吸附特性的研究

【目的】以扎龙湿地污染的土壤为材料,进行耐铅镉菌株的分离鉴定,研究不同条件对菌株吸附铅镉的影响。【方法】采用平板划线法,逐级驯化,筛选出一株耐铅镉菌株,通过生理生化特征及ITS序列分析对菌株进行鉴定,探究该菌吸附的最佳条件,并进行Langmuir和Freundlich等温吸附模型拟合。【结果】本研究分离得到一株菌株JB15,最高耐受浓度为Pb~(2+)1200 mg/L、Cd~(2+)200 mg/L,经鉴定为球孢白僵菌,最佳吸附条件温度为30°C,pH为7.0,接菌量为8.0 g/L,吸附时间为60 min,铅镉吸附率分别为52.27%和62.38%;铅镉吸附量分别为19.60 mg/g和3.98 mg/g,符合Langmuir等温吸附模型。【结论】菌株JB15具有较好的吸附效果,可为微生物修复重金属土壤污染提供理论基础。     

重金属胁迫对真菌生长及发酵液pH的影响

【背景】矿区废渣堆重金属污染严重,废渣堆分布着一些耐重金属的微生物。【目标】探究重金属胁迫对真菌生长及发酵液pH的影响。【方法】从金川矿区废渣堆采集土样,分离培养具有产酸能力的真菌,采用形态学与分子生物学技术鉴定这些菌株,并测定其产酸能力及其对Pb~(2+)、Cd~(2+)和Zn~(2+)的耐受性。【结果】形态学及18S rRNA基因序列分析获得黑曲霉ZJ-I (Aspergillus niger ZJ-I)和产黄青霉ZJ-V (Penicilium chrysogenum ZJ-V)两个产酸菌株。未加重金属培养时,与不接种真菌对照相比,上述2个菌株的发酵液pH分别下降0.58和0.69;添加重金属处理后,随着重金属浓度的增加,pH变化幅度变小,不同浓度Pb~(2+)使A.nigerZJ-I发酵液pH值分别下降0.53、0.39、0.34和0.39,使P. chrysogenum ZJ-V发酵液pH值分别下降0.21、0.23、0.14和0.09;不同浓度Cd~(2+)使A. niger ZJ-I发酵液pH值分别下降0.75、0.43、0.39和0.32,使P. chrysogenum ZJ-V发酵液pH值分别下降0.62、0.46、0.38和0.49;不同浓度Zn~(2+)可使A.nigerZJ-I发酵液pH分别下降0.87、0.61、0.57和0.43,使P. chrysogenum ZJ-V发酵液pH分别下降1.1、0.34、0.44和0.49;低浓度的Zn~(2+)对菌株A.niger ZJ-I和P. chrysogenum ZJ-V产酸都有促进作用,低浓度的Cd~(2+)对A. niger ZJ-I产酸有促进作用。当Cd~(2+)、Zn~(2+)与Pb~(2+)的浓度分别超过200、400、2 000 mg/L时,3种不同浓度的重金属对菌株A. niger ZJ-I的抑制率达到80%以上,抑制效果显著;当Cd~(2+)、Zn~(2+)与Pb~(2+)浓度分别超过200、1 000、2 000 mg/L时,3种不同浓度的重金属对菌株P.chrysogenumZJ-V抑制率达到80%以上,抑制效果显著。【结论】两株真菌均具有产酸能力和一定的重金属耐受性,菌株P. chrysogenum ZJ-V发酵液产酸性能与重金属耐受能力都要优于ZJ-I,菌株ZJ-V具备潜在的淋洗重金属污染土壤的能力。     

Biosorption of lead, cadmium, and zinc by Citrobacter strain MCM B-181: characterization studies

The biosorption process for removal of lead, cadmium, and zinc by Citrobacter strain MCM B-181, a laboratory isolate, was characterized. Effects of environmental factors and growth conditions on metal uptake capacity were studied. Pretreatment of biomass with chemical agents increased cadmium sorption efficiency; however, there was no significant enhancement in lead and zinc sorption capacity. Metal sorption by Citrobacter strain MCM B-181 was found to be influenced by the pH of the solution, initial metal concentration, biomass concentration, and type of growth medium. The metal sorption process was not affected by the age of the culture or change in temperature. Equilibrium metal sorption was found to fit the Langmuir adsorption model. Kinetic studies showed that metal uptake by Citrobacter strain MCM B-181 was a fast process, requiring <20 min to achieve >90% adsorption efficiency. The presence of cations reduced lead, zinc, and cadmium sorption to the extent of 11. 8%, 84.3%, and 33.4%, respectively. When biomass was exposed to multimetal solutions, metals were adsorbed in the order Co2+ < Ni2+ < Cd2+ < Cu2+ < Zn2+ < Pb2+. Among various anions tested, only phosphate and citrate were found to hamper metal sorption capacity of cells. Biosorbent beads prepared by immobilizing the Citrobacter biomass in polysulfone matrix exhibited high metal loading capacities. A new mathematical model used for batch kinetic studies was found to be highly useful in prediction of experimentally obtained metal concentration profiles as a function of time. Metal desorption studies indicated that Citrobacter beads could, in principle, be regenerated and reused in adsorption-desorption cycles. In an expanded scale trial, biosorbent beads were found to be useful in removal/recovery of metals such as lead from industrial wastewaters.     

土壤中镉、铅、锌及其相互作用对作物的影响

通过作物盆栽模拟试验(砂壤质褐土、pH值8.2)揭示：土壤中分别施入镉(CdCl2)、铅[Pb(CH3COO)2]或锌(ZnSO4)其影响表现为,植物各器官镉的含量超过对照植物的数倍至500倍。土壤镉浓度<5ppm和<10ppm分别造成某些蔬菜和水稻的污染。铅主要积累在植物根部,土壤铅污染对作物的影响较小。锌主要积累在植物叶片和根部,对水稻产生生长抑制的土壤锌浓度临界值不大于200ppm,此浓度对旱作无影响。土壤中同时施入镉和铅,植物对镉的吸收增加。而土壤中镉的增加却减少了植物体内铅的含量。土壤中由于镉、锌或铅、锌相互作用的结果,水稻对它们的吸收都有增加。在旱地土壤锌浓度的增高,降低了植物对镉、铅的吸收。镉、铅、锌同时施入土壤由于相互作用的结果,除锌之外,植物对镉、铅的吸收有明显下降。评价土壤重金属污染,不仅要看它们的含量及其存在形态,而且要分析它们之间的相互作用(促进或拮抗)特点。     

一株红假单胞菌的分离及对Cu2+的去除

【背景】重金属污染对环境和人类的健康构成了重大威胁,因此,重金属污染的治理迫在眉睫。生物治理因成本低、处理效果好和无二次污染等优点,在处理重金属污染时被优先选择。【目的】从辽河入海口深13 m的水体中,利用紫色非硫细菌富集培养基筛选产色素能力强并对高浓度Cu~(2+)有高效去除能力的菌株。【方法】采用形态学、生理生化特性和分子生物学方法鉴定菌种;采用二乙基二硫代氨基甲酸钠分光光度法测定Cu~(2+)的含量。【结果】鉴定菌株为红假单胞菌属,将其命名为Rhodopseudomonas sp. gh32。菌株gh32的最适生长温度和最适pH分别为30°C和7.0,其在pH 5.0-10.0范围内可正常生长,在3 mmol/L的CuSO4溶液中能够正常生长,能利用葡萄糖、甘露糖和果糖等单糖和硫化氢。菌株gh32在24h内对Cu~(2+)的去除率均在99%以上,处理能力为1 331 g/g干菌重或167.6 g/g湿菌重。【结论】菌株gh32对Cu~(2+)具有较强的耐受性和很好的去除效果,是治理含Cu~(2+)废水的潜力菌株。本研究为生物治理重金属废水提供了支持。     

Assessment of Heavy Metals Pollution in Sediments of the Korbevačka River in Southeastern Serbia

The Korbeva?ka River is located in the southeastern part of Serbia. This river is a main recipient of all kinds of pollutants from the Pb?Zn mine “Grot.” Sediments from the Korbeva?ka River were studied to determine the distribution of the metals along the river, assess the quality of sediment, and find the degree of contamination. The concentration of iron, manganese, nickel, copper, zinc, cadmium, lead, mercury, arsenic, chromium, and barium were determined. River sediments were collected and analyzed for heavy metal concentration using atomic absorption spectrophotometer. The degree of pollution in the sediments of the Korbeva?ka River has been evaluated based on Canadian sediment quality guidelines, enrichment factor (EF), geo-accumulation index (I_geo) and pollution load index (PLI). Inter-metal associations have been evaluated by Pearson correlation coefficients (r). The results indicated that: (1) sediments have been polluted with Pb, Cd, Zn, and Cu and have high anthropogenic influences; (2) the calculation of geo-accumulation index suggests that the Korbeva?ka River sediments have background concentrations of Fe, Cr, and Ni (I_geo < 1); (3) the co-precipitation (inclusion, occlusion, and adsorption) of heavy metals (except As and Ba) with Mn and Fe geochemical phases.     

Study on the Adsorption of Cr3+ by Peanut Shell: Adsorption Kinetics,Thermodynamics, and Isotherm Properties

The pollution of heavy metals in soil to the environment is becoming more and more serious, resulting in the reduction of crop production and the occurrence of medical accidents. In order to remove heavy metal ions from soil and reduce the harm of heavy metals to the environment, modified peanut shell was used to adsorb Cr³⁺ in this article. The effects of different adsorption conditions on the adsorption rate and adsorption capacity of Cr³⁺ on ZnCl₂ modified peanut shell were studied, the best adsorption conditions were explored, and the relationship of kinetics, thermodynamics and adsorption isotherm properties of adsorption process were explored. The results showed that the optimum adsorption pH value, dosage, initial concentration, adsorption temperature and contact time of ZnCl₂ modified peanut shell were 2.5, 2.5 g/L, 75 μg/mL, 25 °C and 40 min, respectively. The prepared materials were characterized and analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD) analyzer. It was concluded that the modified peanut shell had a good adsorption capacity to Cr³⁺. The kinetic study showed that the adsorption process of Cr³⁺ on peanut shell modified by zinc chloride was in accordance with the quasi-second-order kinetic model. The adsorption process belonged to exothermic reaction and belonged to spontaneous reaction process. In summary, it is proved that zinc chloride modified peanut shell can efficiently adsorb Cr³⁺, which can be used for the treatment of heavy metal wastes in industry, which is beneficial to environmental protection and avoid heavy metal pollution.     

Metal Pollution Assessment in Sediments of the Southeastern Black Sea Coast of Turkey

The main objective of this investigation is to determine the concentration and accumulation of heavy metals in the coastal sediments of the Southeastern Black Sea of Turkey. The selected sampling area has mainly been affected by anthropogenic activities, such as agricultural, untreated domestic and treated industrial wastewater, and mining. Metal enrichment factor (EF), geo-accumulation index (I_geo), and metal pollution index (MPI) have been calculated and relative contamination levels evaluated at all stations. In this study, the maximum EF values calculated for nickel (Ni), cobalt (Co), cadmium (Cd), lead (Pb), chromium (Cr), arsenic (As), zinc (Zn), and copper (Cu) were 1.4, 3.1, 5.2, 7.8, 7.8, 20, 26, and 42, respectively. Metal pollution has decreased in recent years, but the enrichment of heavy metals has been observed to be relatively high, especially in the uppermost 3-6 cm of the core sample from the Sürmene sampling station, which has been polluted by mining activities. In addition, factor analysis revealed that the coastal sediments from the Eastern Black Sea were influenced by several sources, namely lithogenic and anthropogenic activities (mining, wastewater discharging, agriculture).     

The metal distribution and the change of physiological and biochemical process in soybean and mung bean plants under heavy metal stress

Soybean [Glycine max (Linn.) Merrill] and mung bean [Vigna radiate (Linn.) Wilczek] plants were challenged with 5 kinds of heavy metals [cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb) and mercury (Hg)] in a hydroponic system. We applied 4 different metal treatments to study the effects of heavy metals on several physiological and biochemical parameters in these species, including root length, heavy metal concentrations and allocation in different organs, superoxide dismutase, catalase, and peroxidase activities, the content of malondialdehyde (MDA), protein and chlorophyll. The data showed that the growth of the roots of soybean and mung bean was equally sensitive to external Hg concentrations. Soybean was more sensitive to external Cd concentrations, and mung bean was more sensitive to external Cr, Cu and Pb concentrations. Normal concentrations of heavy metal would not cause visible toxic symptoms, and a low level of heavy metal even slightly stimulated the growth of plants. With the rise of heavy metal concentration, heavy metal stress induces an oxidative stress response in soybean and mung bean plants, characterized by an accumulation of MDA and the alternation pattern of antioxidative enzymes. Meanwhile, the growth of plants was suppressed, the content of chlorophyll decreased and leaves showed chlorosis symptoms at high metal concentrations.     

耐铅镉菌株的分离鉴定及其吸附能力

堆肥中添加生物钝化剂是当前降低粪便中重金属生物毒性最为有效的方式之一,为了进一步提高其钝化重金属的能力,文中获得了复合重金属高耐性的钝化剂菌株,并探究其生物学特性和吸附特征。采集猪粪堆肥样品并在改良的牛肉膏培养基中分离和筛选耐铅又耐镉的高耐性菌株,通过形态结合分子生物学鉴定该菌株。该菌株分别在不同pH、温度和盐浓度条件下培养获得其最适的生长条件,进而在该条件下分析其对铅镉吸附的特性。结果获得一株耐铅浓度为600 mg/L、镉浓度为120 mg/L的铅镉复合耐性菌株SC19,该菌株为西地西菌属,其最适生长环境为pH值7.0、温度37℃、盐浓度0.5%。培养36 h的稳定期SC19菌株在吸附时间30min时铅的去除率最高,对铅的最大去除率和吸附量分别为60.7%和329.13mg/g;培养8h的对数期在吸附时间30min时镉的去除率最高,对镉的最大去除率和吸附量分别为51.0%和126.19 mg/g。红外光谱分析显示,SC19菌株对铅镉离子的吸附主要是细胞表面的多种活性基团与金属离子发生络合作用。该研究揭示了SC19菌株有较好的二价态铅镉离子吸附能力,可为生物钝化重金属提供重要的微生物种质资源。