不同二氧化碳浓度条件下红松和长白赤松幼苗根际土壤微生物数量研究

以连续5年不同CO₂浓度(开顶箱700μmol·mol^-1、500μmol·mol^-1、对照箱和裸地)处理的长白赤松和红松幼苗为研究对象,在2003年7～9月分别对幼苗根际土壤细菌、真菌、放线菌数量进行比较研究.结果表明,高浓度CO₂处理对长白赤松幼苗根际土壤细菌数量起显著的(P≤0.001)促进作用,对根际真菌和放线菌数量的促进作用却不明显;对红松来说,除8月份700μmol·mol^-1CO₂处理和7月份500μmol·mol^-1CO₂处理之外,在各月份中受高浓度CO₂处理的根际土壤细菌数量均较对照箱和裸地显著增多(P≤0.001),而根际土壤真菌数量变化除9月份(P≤0.001)外均不明显,放线菌数量受高浓度CO₂的影响亦不明显.     

黑杨水培中营养液抑菌处理研究

水培条件下进行快速繁殖是大量生产黑杨种苗的途径之一 ,营养液的抑菌处理是水培的一个重要方面。该研究进行了二硫氰甲烷、中生菌素、敌磺钠、链霉素、青霉素等五种杀细菌剂和多菌灵、福美双、三唑酮等三种杀真菌剂的抑菌试验 ,结果表明 ,杀细菌剂对微生物生长的抑制率要高于杀真菌剂 ,二硫氰甲烷和中生菌素能较好地抑制营养液中微生物的生长 ,浓度分别为 2 0mg/L和 1 5mg/L时 ,抑制率分别为 75 .60 %和78 94%。杀真菌剂和杀细菌剂复配对营养液中微生物生长的抑制表现出较好的加和作用 ,其中以中生菌素(1 5mg/L)与福美双 (5mg/L)复配的效果最好 ,抑制率为 87.48%。     

Cr6+胁迫对小麦幼苗根系生长的影响及DNA损伤效应研究

研究了Cr6+胁迫对3 d和10 d龄小麦幼苗根系生长的影响及DNA损伤效应.结果表明(1)>5 mg/L的Cr6+均显著或极显著降低幼苗根长、根数及根系鲜重、干重,3 d龄幼苗根系生长比10 d龄幼苗对Cr6+胁迫更敏感;(2)所试浓度Cr6+均降低两苗龄幼苗根系DNA含量;5～20 mg/L Cr6+浓度范围内,3 d龄幼苗根系DNA含量下降幅度大于10 d龄幼苗,Cr6+浓度>20 mg/L时,3 d龄幼苗根系DNA含量低于10 d龄幼苗;(3)Cr6+对两苗龄幼苗根系DNA增色效应的影响均呈现随浓度增大先升高后下降的趋势;3 d龄幼苗根系DNA增色效应在5～60 mg/L Cr6+浓度范围内大于对照,Cr6+浓度>60 mg/L时则小于对照;在所试Cr6+浓度范围内,10 d龄幼苗根系DNA增色效应均大于对照.     

蚯蚓和秸秆对铜污染土壤微生物类群和活性的影响

试验设置4个Cu浓度水平：0、100、200和400 mg·kg^-1 Cu²⁺,每个Cu浓度水平设置4个处理：对照(CK)、表施秸秆(M)、接种蚯蚓(E)、同时加入蚯蚓和秸秆(ME),研究了在Cu污染土壤中加入蚯蚓和秸秆对土壤微生物数量及活性的影响.结果表明：Cu污染、秸秆和蚯蚓均明显影响土壤微生物类群; Cu污染对细菌、放线菌具有抑制作用,而对真菌没有影响;秸秆显著提高了真菌数量;蚯蚓使土壤细菌、放线菌数量显著增加,而对真菌数量影响不大.Cu污染浓度＞200 mg·kg^-1处理对微生物量碳具有抑制作用;加入秸秆或蚯蚓,可显著提高土壤微生物量碳,而且同时加蚯蚓和秸秆处理土壤微生物量碳增加最显著.加入蚯蚓和秸秆后,土壤呼吸值显著增高.Cu<200 mg·kg^-1时,蚯蚓处理土壤呼吸值最大,平均比对照高3.06～5.58倍;Cu≥200mg·kg^-1时,蚯蚓、秸秆同时加入处理土壤呼吸值最高.4个处理土壤代谢商大小顺序为：ME>E>M>CK.蚯蚓和秸秆处理对土壤NH₄⁺-N没有影响,而对土壤NO₃^--N影响各异.接种蚯蚓,可显著提高土壤NO₃^--N含量;加入秸秆,可显著降低土壤NO₃^--N含量;同时加入蚯蚓和秸秆处理NO₃^--N含量最低.相关分析表明,土壤有效态Cu(DTPA-Cu)与土壤放线菌、细菌呈显著负相关,而与土壤呼吸、土壤NO₃^--N、NH₄⁺-N含量呈显著正相关.引入秸秆和蚯蚓,可在一定程度上减缓Cu污染对微生物数量和活性的影响.     

水淹生境下秋华柳对Cd污染土壤微生物数量及酶活性的影响

三峡库区消落带面临水淹及Cd污染双重胁迫,为探究秋华柳(Salix variegata Franch.)在水淹条件下对Cd污染土壤的修复能力,以秋华柳扦插苗为试验材料,设置正常供水(CK)和水淹组(FL)两个水分处理方式,4个Cd浓度梯度:对照组(0mg/kg)、低浓度(0.5mg/kg)、中浓度(2mg/kg)及高浓度(10mg/kg),分别对处理60 d和120 d的土壤微生物数量及酶活性变化特征进行研究。试验结果表明:(1)Cd浓度处理均未显著影响土壤微生物数量(P0.05),水淹显著降低处理60 d土壤细菌数、真菌数及处理120 d的土壤放线菌数及真菌数(P0.05)。(2)种植秋华柳显著提高处理60 d土壤细菌数量(P0.05),对土壤放线菌、真菌数量也有一定提升。(3)Cd浓度处理显著影响处理60 d土壤磷酸酶活性及处理120 d脲酶活性(P0.05),水淹显著降低处理60 d土壤磷酸酶活性及处理120 d脲酶、蔗糖酶和磷酸酶活性(P0.05)。(4)正常供水及水淹条件下,种植秋华柳对土壤酶活均有一定改善作用。种植秋华柳显著提高了处理60 d土壤磷酸酶活性以及处理120 d脲酶和蔗糖酶活性(P0.05)。研究结果表明:水淹生境中,秋华柳对Cd污染土壤微生物数量及酶活性具有改善作用,在Cd污染土壤修复方面有一定应用前景。     

转Bt基因水稻秸秆降解对土壤微生物可培养类群的影响

以高抗螟虫、已释放应用的 Bt水稻 (克螟稻 1号 )及其亲本 (非 Bt水稻 )为材料 ,在实验室条件下研究了转 Bt基因水稻及其亲本秸秆在降解过程中对土壤微生物主要类群的影响 ,这些类群包括细菌、真菌、放线菌、反硝化细菌、解磷微生物。结果表明 :(1)降解过程中 Bt蛋白浓度在前两周内迅速下降 ,随后降解速度变慢 ,17d以后至 5 3d,Bt蛋白浓度基本上保持在 6 .72 8～6 .196 ng/ g的水平。 (2 )秸秆降解过程中 ,不同处理细菌数量的变化趋势相似 ,转基因水稻与其亲本之间差异显著 ,非转基因细菌数量高于转基因细菌数量。(3)除降解初期第 3天、第 6天之外 ,其他取样时期的转基因水稻真菌数量要显著高于非转基因和对照。(4)放线菌数量没有明显变化规律 ,除第 6、9、2 6、35天外 ,非转基因数量显著高于转基因。(5 )非转基因秸秆降解反硝化细菌活性高于转基因 ,而解磷微生物活性处理之间无明显差异。     

从铅锌矿渣中分离的微生物对重金属吸附特性的研究

从铅锌矿渣中分离到 16种菌 (包括 7株细菌和 9株真菌 ) ,并研究了它们对Zn2 + ,Pb2 + ,Cu2 + 的吸附特性。发现大多数菌株对Pb2 + 与Zn2 + 有不同程度的吸附 ,但对Cu2 + 的吸附能力较小。菌株对Zn2 + 的吸附率大于对Pb2 + 的吸附 ,能吸附Pb2 + 的菌株也能吸附Zn2 + 。pH 4～ 6是真菌吸附金属离子的较好范围 ,细菌仅在pH =5 .0条件下 ,对Pb2 + 与Zn2 + 有吸附。在测试的不同金属离子浓度范围内 (5 0mg/L 相似文献   

Cr6+对人工湿地薏苡光合特性和微量元素吸收的影响

为深入了解Cr⁶⁺胁迫对人工湿地植物薏苡光合特性和微量元素吸收的影响,该文通过构筑微型垂直流薏苡(Coix lacryma-jobi)人工湿地,采用1/2 Hoagland’s营养液配制的含0、5、20、40 mg·L^-1 Cr⁶⁺废水为灌溉用水,研究铬胁迫对人工湿地植物生长、光合特性、抗氧化酶活性和微量元素吸收等的影响。结果表明：(1)低浓度(5 mg·L^-1)Cr⁶⁺对薏苡的株高、茎粗和分蘖影响不显著,高浓度(20、40 mg·L^-1)Cr⁶⁺则显著抑制薏苡的生长。(2)低浓度Cr⁶⁺处理下,薏苡叶片净光合速率(P_n)、气孔导度(G_s)和蒸腾速率(T_r)有不同程度的提高,提高幅度分别为6.8%～54.8%、13.0%～40.3%和9.1%～36.4%。高浓度Cr⁶⁺处理下,叶片P_n、G_s     

岷江冷杉根际土壤微生物对大气CO2浓度和温度升高的响应

应用自控、封闭、独立的生长室系统,研究了川西亚高山岷江冷杉根际土壤微生物数量对大气CO₂浓度升高 (环境CO₂浓度+350(±25)μmol·mol^-1,EC)和温度升高(环境温度+2.2(±0.5)℃,ET)及其CO₂浓度和温度同时升高 (ECT)的响应.结果表明,1)同对照(CK)相比,在6月、8月和10月,EC处理的根际细菌数量分别增加了35%、164%和312%,ET处理增加了30%、115%和209%,而EC和ET处理对根际放线菌和根际真菌数量影响不显著;ECT处理的根际放线菌数量分别增加了49%、50%和96%,根际真菌数量增加了151%、57%和48%,而ECT对根际细菌数量影响不显著.2)3种处理对非根际土壤微生物数量影响均不显著.3)在EC、ET和ECT处理下,微生物总数的根际效应明显,其R/S值分别为1.93、1.37和1.46(CK的R/S值为0.81).     

重金属Cr6+胁迫对茳芏生理生态特征的影响

采用盆栽模拟试验,研究了不同水平重金属Cr6+对茳芏生理生态的影响,探索了茳芏对重金属的抗性机理,充实有关盐沼植物的污染生态学研究。结果表明:(1)Cr6+胁迫对茳芏生物量具抑制作用;(2)叶绿素含量及叶绿素a/b比值显著降低,并对净光合速率(Pn)、胞间CO2浓度(Ci)、蒸腾速率(Tr)及气孔导度(Gs)产生显著负面影响;(3)各浓度Cr6+胁迫对茳芏根系活力表现为抑制效应;(4)在Cr6+胁迫下,茳芏过氧化氢酶(CAT)活性均比对照低(除50mg/L外),超氧化歧化酶(SOD)活性随Cr6+浓度增加呈降低趋势,而过氧化物酶(POD)活性则持续上升。丙二醛(MDA)、细胞膜透性和脯氨酸(Pro)随Cr6+浓度增加显著增加,表明Cr6+胁迫对茳芏细胞质膜系统及主要细胞器的结构与功能都具有较强的破坏作用。     

The Reduction of Cr(VI) by Bacteria of the Genus Pseudomonas

Non-nitrate-reducing collection bacteria from the genus Pseudomonas were found to be able to use hexavalent chromium as a terminal electron acceptor. The reduction of Cr(VI) was accompanied by an increase in the cell biomass. At Cr(VI) concentrations in the medium lower than 15 mg/l, the non-nitrate-reducing pseudomonads reduced Cr(VI) less efficiently than did denitrifying pseudomonads. In contrast, at Cr(VI) concentrations higher than 30 mg/l, Cr(VI) was reduced more efficiently by the non-nitrate-reducing pseudomonads than by the denitrifying pseudomonads.     

The reduction of Cr(VI) by bacteria of the genus Pseudomonas

Non-nitrate-reducing collection bacteria from the genus Pseudomonas were found to be able to use hexavalent chromium as a terminal electron acceptor. The reduction of Cr(VI) was accompanied by an increase in the cell biomass. At the Cr(VI) concentrations in the medium lower than 15 mg/l, the non-nitrate-reducing pseudomonads reduced Cr(VI) less efficiently than did denitrifying pseudomonads. In contrast, at the Cr(VI) concentrations higher than 30 mg/l, Cr(VI) was reduced more efficiently by the non-nitrate-reducing pseudomonads than by the denitrifying pseudomonads.     

六价铬在斜带石斑鱼胚胎中的生物累积及其对igf2、glut2和pparg基因表达的影响

以斜带石斑鱼(Epinephelus coioides)为研究对象, 探讨了水中不同浓度梯度六价铬(0、0.20、0.60、1、5、10、20、40、60和80 mg/L)在胚胎发育不同阶段(桑葚期、囊胚期、原肠末期、脑泡形成期和心脏跳动期)的生物累积及其对细胞生长基因igf2和营养代谢基因glut2、pparg的mRNA表达的影响。结果表明, 胚胎中Cr6+生物累积量和吸收率随暴露浓度的增加而增加, 且吸收率随胚胎发育时期的延伸而降低。在桑葚期时, 斜带石斑鱼胚胎吸收Cr6+能力最强, 是心脏跳动期的20倍。在桑葚期、囊胚期和原肠末期, Cr6+对胚胎中igf2和glut2基因mRNA表达水平有显著促进作用(P<0.05), 但对pparg基因mRNA表达水平有显著抑制作用(P<0.05)。在原肠末期和脑泡形成期, Cr6+对胚胎中pparg基因mRNA表达水平有显著促进作用(P<0.05)。研究表明水中Cr6+暴露在斜带石斑鱼胚胎发育过程中有明显的生物累积, 且对细胞生长水平和营养代谢有明显的影响, 研究为斜带石斑鱼早期生活史阶段适宜生境和资源保护提供了理论基础。     

Characteristics of a novel Acinetobacter sp. and its kinetics in hexavalent chromium bioreduction

Cr-B2, a Gram-negative hexavalent chromium [Cr(VI)] reducing bacteria, was isolated from the aerator water of an activated sludge process in the wastewater treatment facility of a dye and pigment based chemical industry. Cr- B2 exhibited a resistance for 1,100 mg/l Cr(VI) and, similarly, resistance against other heavy metal ions such as Ni2+ (800 mg/l), Cu2+ (600 mg/l), Pb2+ (1,100 mg/l), Cd2+ (350 mg/l), Zn2+ (700 mg/l), and Fe3+ (1,000 mg/l), and against selected antibiotics. Cr-B2 was observed to efficiently reduce 200 mg/l Cr(VI) completely in both nutrient and LB media, and could convert Cr(VI) to Cr(III) aerobically. Cr(VI) reduction kinetics followed allosteric enzyme kinetics. The Km values were found to be 43.11 mg/l for nutrient media and 38.05 mg/l for LB media. Vmax values of 13.17 mg/l/h and 12.53 mg/l/h were obtained for nutrient media and LB media, respectively, and the cooperativity coefficients (n) were found to be 8.47 and 3.49, respectively, indicating positive cooperativity in both cases. SEM analysis showed the formation of wrinkles and depressions in the cells when exposed to an 800 mg/l Cr(VI) concentration. The organism was seen to exhibit pleomorphic behavior. Cr-B2 was identified on the basis of morphological, biochemical, and partial 16S rRNA gene sequencing chracterizations and found to be Acinetobacter sp.     

油田外排水对干旱戈壁区人工湿地土壤微生物生物量的影响

为研究油田外排水对干旱戈壁区人工湿地土壤微生物生物量的影响,选择干旱戈壁区某油田外排水形成的湿地内坝内、内外坝间、外坝边缘土壤,及不受排水影响的对照土壤,采用磷脂脂肪酸(PLFA)方法,分析外排水对土壤细菌、真菌、放线菌生物量的影响。结果表明:湿地内坝内、内外坝间、外坝边缘土壤与对照土壤的pH和容重均无显著差异,内外坝间的土壤含水量、电导率、溶解性全盐和全碳含量最高,显著高于内坝内土壤;除含水量外,对照土壤的主要物理性质和养分特征与湿地内坝内、内外坝间、外坝边缘的土壤无显著差异。土壤总微生物量、细菌和真菌生物量从湿地内坝内至外坝边缘逐渐增加。土壤总微生物量、细菌、真菌、放线菌与全氮含量均呈显著正相关,丛枝菌根真菌与全碳呈显著正相关,真菌、丛枝菌根真菌与总石油烃呈显著正相关。研究结果表明,油田外排水增加了湿地外坝边缘的土壤微生物量。     

Removal of hexavalent chromium using distillery sludge

Batch mode experiments were conducted to study the removal of hexavalent chromium from aqueous and industrial effluent using distillery sludge. Effects of pH, contact time, initial concentration and adsorbent dosage on the adsorption of Cr(VI) were studied. The data obeyed Langmuir and Freundlich adsorption isotherms. The Langmuir adsorption capacity was found to be 5.7 mg/g. Freundlich constants K(f) and n were 2.05 [mg/g(L/mg)(n)] and 3.9, respectively. Desorption studies indicated the removal of 82% of the hexavalent chromium. The efficiency of adsorbent towards the removal of chromium was also tested using chromium-plating wastewater.     

Bio-reduction of Cr(VI) by exopolysaccharides (EPS) from indigenous bacterial species of Sukinda chromite mine, India

Chrome mining activity has contributed intensively towards pollution of hexavalent chromium around Sukinda Valley, Orissa, India. In an attempt to study the specific contribution of exopolysaccharides (EPS) extracted from indigenous isolates towards Cr(VI) reduction, three chromium (VI) tolerant strains were isolated from the effluent mining sludge. Based on the tolerance towards Cr(VI) and EPS production capacity, one of them was selected for further work. The taxonomic identity of the selected strain was confirmed to be Enterobacter cloacae (showing 98% similarity in BLAST search to E. cloacae) through 16S rRNA analysis. The EPS production was observed to increase with increasing Cr(VI) concentration in the growth medium, highest being 0.078 at 100?mg/l Cr(VI). The extracted EPS from Enterobacter cloacae SUKCr1D was able to reduce 31.7% of Cr(VI) at 10?mg/l concentration, which was relevant to the prevailing natural concentrations at Sukinda mine effluent sludge. The FT-IR spectral studies confirmed the surface chemical interactions of hexavalent chromium with EPS.     

Preliminary studies on continuous chromium(VI) biological removal from wastewater by anaerobic-aerobic activated sludge process

The long-term continuous chromium(VI) removal from synthetic wastewater affected by influent hexavalent chromium (Cr(VI)) and glucose concentrations were studied with an anaerobic-aerobic activated sludge process. It was observed that before activated sludge was acclimated, the chromium in the effluent increased immediately as the influent chromium increased. However, both Cr(VI) and total chromium (TCr) in the effluent significantly decreased after acclimation. In the acclimated activated sludge, the chromium removal efficiency was 100% Cr(VI) and 98.56% TCr at influent Cr(VI) levels of 20 mg/day, 100% Cr(VI) and 98.92% TCr at influent Cr(VI) levels of 40 mg/day, and 98.64% Cr(VI) and 97.16% TCr at influent Cr(VI) levels of 60 mg/day. The corresponding effluent Cr(VI) and TCr concentrations were 0 and 0.012 mg/l, 0 and 0.018 mg/l, and 0.034 mg/l and 0.071 mg/l, respectively. When the influent glucose increased from 1125 to 1500 mg/l at influent Cr(VI) dosage of 60 mg/day, the Cr(VI) and TCr removal efficiency with the acclimated activated sludge improved from 98.64% and 97.16% to 100% and 98.48%, respectively, and the chromium concentration in the effluent decreased from 0.034 mg/l of Cr(VI) and 0.071 mg/l of TCr to 0 (Cr(VI)) and 0.038 mg/l (TCr). The effluent COD and turbidity was around 40 mg/l and 0, respectively, after the activated sludge was acclimated. Further studies showed that after the activated sludge was acclimated, its specific dehydrogenases activity (SDA) and protein contents increased. The SDA and protein increased respectively 15% and 10% when influent Cr(VI) increased from 20 to 60 mg/day.     

Reduction of high concentrations of chromate by Leucobacter sp. CRB1 isolated from Changsha, China

In recent years, more and more attentions are put on the remediation of Cr(VI) contamination with chromate resistant bacteria. Leucobacter sp. CRB1 was a novel chromate reducing bacteria isolated from the soil of chromite ore processing residue (COPR) disposal site in Changsha, China. The objectives of this study were to evaluate the Cr(VI) tolerance of Leucobacter sp. CRB1 as well as its tolerant mechanism, and Cr(VI) reduction ability. The results showed that Leucobacter sp. CRB1 was able to tolerate 4,000 mg/l of hexavalent chromium with 34.5% reduction efficiency. At the optimum pH 9.0, the maximum concentration of chromate be reduced completely was 1,818 mg/l in growing cells and 2,100 mg/l in resting cells. Scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) showed that extracellular Cr(VI) reduction of Leucobacter sp. CRB1 contributed to its high tolerance and high reduction ability. With repeating spiking, 2,490 mg/l hexavalent chromium was reduced totally within 17 h. The results suggest Leucobacter sp. CRB1 has potential application for remediation of high concentration of Cr(VI) contamination.     

Hexavalent Chromium Reduction in Soils Contaminated with Chromated Copper Arsenate Preservative

The toxicity and mobility of chromium in the environment greatly depends upon its speciation. The reduction of hexavalent chromium to trivalent chromium in a soil environment was examined by spiking three soil types (sandy, clayey, and organic soils) with a common wood preservative solution known as chromated copper arsenate (CCA). Chromium in the CCA preservative solution exists in the hexavalent form. The total and hexavalent chromium concentrations (mg/kg) were measured over a period of 11 months. Leachable chromium concentrations (mg/L) were assessed using the synthetic precipitation leaching procedure (SPLP). The degree and rate of hexavalent chromium reduction were similar for the sand and clayey soil, but much greater for the organic soil. Most of the chromium reduction occurred within the first month of the experiment. At the end of the experiment, approximately 50% of the hexavalent chromium was converted to the trivalent form in the sand and clayey soils. Hexavalent chromium concentrations were below detection in the organic soil at the end of the experiment. Nearly all of the chromium observed in the SPLP leachates was in the form of hexavalent chromium. Chromium leaching was thus greatest in the sand and clay soils where the hexavalent chromium persisted. The results indicate that hexavalent chromium in soils can persist for considerable time periods, in particular in soils with low organic matter content.