一株高效耐冷菌的分离鉴定及降解特性研究

寒冷地区水温偏低,污水生物处理效果差,出水达标困难。从寒冷地区水土样品中,分离到数株能在2℃下生长的低温菌株,选择优势菌N进行重点研究。从脱氢酶活性机制上,考察了不同条件对N菌株降解能力的影响;对比研究了它与常温活性污泥降解能力和脱氢酶活性的差异。结果表明:N菌株属于耐冷型低温微生物,结合16S rDNA序列同源性分析及生理生化特性鉴定为黄假单胞菌;5℃曝气8 h,接种废水COD、氨氮去除率均在90%以上;低温条件下,该耐冷菌对生活污水降解率比常温活性污泥高出40%,脱氢酶具有更高的活性,在低温污水处理方面具有广阔的应用前景。     

In vivo and in vitro metabolism of tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), by the freshwater planarian, Dugesia japonica

Cigarette smoke is a risk factor for human health, and many studies were conducted to investigate its adverse effects on humans and other mammals. However, since large amounts of cigarette products are produced and consumed, it is possible that tobacco chemicals can end up in aquatic environments through several routes, thus influencing aquatic organisms. In this study, the presence of tobacco-specific nitrosamine (TSNA), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), in aquatic environment was demonstrated. Since toxic effects on and distribution patterns of tobacco chemicals in aquatic organisms were rarely studied, after results of an acute toxicity pretest were obtained, experiment was conducted to investigate the bioaccumulation pattern of NNK and distribution patterns of its metabolites, mainly 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), in NNK-treated freshwater planarians, Dugesia japonica. Results from in vivo and in vitro studies showed that NNK was readily converted to NNAL through the carbonyl reduction in bodies of NNK-treated planarians. Tissue concentrations of both chemicals increased in time- and dose-dependent manners. Furthermore, we examined the end products of NNK/NNAL α-hydroxylation in NNK-treated planarians, but only 1-(3-pyridyl)-1,4-butanediol was detected, suggesting that NNK metabolism in planarians partially differs from that in mammalian systems. This is the first report on NNK metabolism in an aquatic organism and can be used as a foundation for developing freshwater planarians as a new in vivo model for the study of NNK toxicology in the future.     

餐厨垃圾与剩余污泥混合消化产沼气协同效应

在(35±0.2)℃温度下,以餐厨垃圾和剩余污泥为原料,设置餐厨垃圾和剩余污泥混合比例(VS)分别为1∶0、2∶1、1∶1、1∶2和0∶1,研究其单独消化与混合消化的系统性能、产甲烷潜力及脱氢酶活性和F420浓度变化。结果表明,混合消化提高了系统稳定性,与餐厨垃圾单独消化相比,添加剩余污泥能调节pH、氨氮浓度和VFA浓度,缩短产气周期;与剩余污泥单独消化相比,添加餐厨垃圾能显著提高沼气产量。混合比例为1∶1组混合消化产甲烷潜力最佳,消化作用的协同效应最为明显,沼气和甲烷产量分别达358.2 mL/g VS和224.1 mL/g VS,较餐厨垃圾和污泥单独消化估计值分别提高了23.09%和36.80%。1∶1混合消化组脱氢酶活性最高达437.33 TFμg/(mL·h),比餐厨垃圾和剩余污泥单独消化分别提高93.60%和40.69%,辅酶F420浓度最高为1.718μmol/L,分别提高17.3%和100.7%。     

Blood biomarkers and contaminant levels in feathers and eggs to assess environmental hazards in heron nestlings from impacted sites in Ebro basin (NE Spain)

Blood biomarkers and levels of major pollutants in eggs and feathers were used to determine pollution effects in nestlings of the Purple Heron Ardea purpurea and the Little Egret Egretta garzetta, sampled on three Ebro River (NE Spain) areas: a reference site, a site affected by the effluents of a chlor-alkali industry and the river Delta. The two impacted heron populations showed mutually different pollutant and response patterns, suggesting different sources of contamination. In the population nesting near the chlor-alkali plant, elevated levels of hexachlorobenzene (HCB) and polychlorobiphenyls (PCBs) in eggs, and mercury in feathers in A. purpurea chicks were related with reduced blood antioxidant defenses and increased levels of micronuclei. In Ebro Delta, high levels of plasmatic lactate dehydrogenase in A. purpurea chicks and high frequency of micronuclei in blood of both species were tentatively associated with intensive agricultural activities taking place in the area. These results provide the first evidence of a biological response in heron chicks to the release of pollutants at a chlor-alkali plant.     

二氧化硫对大鼠肺泡细胞和肺泡灌洗液的生化效应

研究了二氧化硫(SO2)对大鼠支气管肺泡灌洗细胞和肺泡灌洗液(BALF)的生化指标的影响。结果表明，吸入SO2后大鼠BALF中肺泡巨噬细胞数量增加、但比例减少，中性粒细胞和淋巴细胞数量和比例均增加，并存在剂量一效应关系；熏气后BALF的pH下降、蛋白质含量和肺通透指数升高，BALF中酸性磷酸酶、碱性磷酸酶和乳酸脱氢酶活性升高，脂质过氧化水平提高：这些细胞和生物化学指标的改变从不同的方面反映了SO2可引起大鼠肺组织和肺泡细胞的结构和功能的损伤。     

生物修复PAHs污染土壤对酶活性的影响

在PAHs污染土壤生物修复过程中,以黑麦草、苜蓿为修复植物,固定化微生物菌剂为外源微生物,通过盆栽实验研究了不同处理对土壤酶活性的影响,以及酶活性与PAHs的去除效果之间的相关性。结果表明,植物修复、微生物修复及两者联合修复均显著提高了土壤PAHs的去除效果,其中黑麦草和苜蓿与微生物菌剂联合修复效果分别达到37.57%和38.41%,比单独的植物修复和菌剂修复高出一倍左右。各种生物修复同时促进了土壤多酚氧化酶、脱氢酶及脲酶的活性,减少了过氧化氢酶活性。过氧化氢酶活性与多酚氧化酶活性呈显著负相关（P〈0.05）、而脲酶与多酚氧化酶显著正相关（P〈0.05）。进一步分析表明PAHs的去除率与脱氢酶活性极显著正相关（P〈0.01）,与多酚氧化酶活性呈显著正相关（P〈0.05）,与过氧化氢酶活性呈负相关（P=0.564）;因此,在PAHs污染土壤生物修复过程中,可以选择土壤脱氢酶活性和多酚氧化酶活性作为PAHs修复效率的微生态指示指标。     

低强度超声波强化低温SMBR脱氮的性能与机制研究

考察了低温条件下低强度超声波对SMBR脱氮的强化作用,并研究了对硝化细菌脱氢酶活性和细胞通透性的影响。结果表明,经超声波强化后,SMBR对NH3-N5的去除效果得到明显提高,总去除率由启动完成时的65.94%升至84.01%,且长期运行稳定,说明超声波解除了低温对硝化作用的抑制。0.28 W/L超声波辐照20 min,可使硝化细菌脱氢酶活性提高81.19%,0.14 W/L的超声波辐照10 min使脱氢酶活性提高43.18%。0.28 W/L的超声功率密度对脱氢酶的活性提高程度最大,因此是较合适的超声波参数。     

制药残留溶剂对废水生物降解系统微生物毒性的测定方法比较

水质生物毒性测定是评价水环境质量的重要内容,制药废水有机物含量高,有些成分可抑制污泥活性或具有生物毒性.为了更准确地评估制药废水的生物毒性,筛选出适用于准确评价污染物对废水生物降解系统中微生物生物毒性的方法,对发光细菌法、脱氢酶活性法、硝化抑制法及呼吸速率法4种生物毒性测定方法进行了比较研究,以甲苯、二甲基甲酰胺、三乙胺3种常见制药有机溶剂为研究对象、氯化汞为标准毒物.结果表明,各测定方法得出的结果不同,根据灵敏度和测定时间,4种方法排序为发光细菌法(2 h)、脱氢酶活性法(7 h)、硝化速率法(120 h)、呼吸速率法(48 h),与其他3种基于活性污泥毒性的测定方法相比,发光细菌法具有最高的灵敏度.3种活性污泥法对有机溶剂的毒性响应具有相同顺序,从高到低为二甲基甲酰胺、三乙胺、甲苯,而发光细菌法与之不同,顺序为三乙胺、甲苯、二甲基甲酰胺.综合考虑测定方法的灵敏度、测试时间、操作简便性,推荐选取灵敏度最高的发光细菌试验和以活性污泥为受试对象的脱氢酶活性法联合使用,将二者综合的测定结果作为判定依据,可以更准确地判定制药残留溶剂对废水生物降解系统的生物毒性.     

Modified dehydrogenase enzyme assay for evaluation of the influence of Hg,Cd, and Zn on the bacterial community structure of a wastewater treatment plant

In this study, a traditional assay was modified to evaluate the effect of Hg, Cd, and Zn on the bacterial community of a sequencing batch reactor and activated sludge plants and heavy metal-resistant bacterial species were determined. After the isolation of metal-resistant bacteria, their 16S rRNA gene fragments were sequenced. The BLAST program was used to compare the resulting 16S rRNA sequences with those in GenBank database to identify the isolated bacterial species. Hg was found to be the most toxic metal for both bacterial communities investigated. Sequence batch reactor bacteria were comparatively more resistant to Hg, Cd, and Zn than those from activated sludge. The resistant strains were close to the members of genus Pseudomonas, Kocuria, Stenotrophomonas, Enterococcus, and Staphylococcus. The modified dehydrogenase enzyme assay seems to be simple, robust, and competent for evaluation of the impact of metals on bacterial activity. Sequencing batch reactor systems should be preferred over activated sludge when wastewaters containing hazardous metals are to be treated.     

Biodegradable nanocomposites based on poly(butylene succinate)/organoclay

In this work, we try to incorporate the inorganic system into the biodegradable polymers to compose an organic/inorganic polymer hybrid. Various nanocomposites of poly(butylene succinates) (PBS) with different ratios of organically modified layered silicates (OMLS) prepared by solution blending were investigated. The OMLS used for the preparation of nanocomposites were functionalized ammonium salts modified montmorillonite. The effects of OMLS on the nanocomposites were investigated by XRD, TEM, DMA and TGA in the aspect of the d-spacing of clay, mechanical and thermal properties. Interestingly, all these nanocomposites exhibited improved properties when compared with the pristine PBS sample. XRD indicates that the layers of clay were intercalated by the modifiers, and the interlayer distance of organoclay in the nanocomposites could be extended to about 29.4 Å. Moreover, the thermal stability of the nanocomposites was enhanced by the addition of organoclay via TGA study, closely related to the organoclay content in the PBS matrix. DMA data shows that the storage and loss moduli were concurrently enhanced by the addition of organoclay as compared to the pristine PBS sample. Moreover, the glass transition temperatures also increased about 5 to 20 °C (from DMA, peak of tanδ) for the various organoclay-containing samples. The enhanced mechanical and thermal properties can be achieved from these organoclay modified-nanocomposites.