生物脱氮中工程纳米颗粒的毒害作用及减毒措施的研究进展

氮化合物在生命代谢过程中扮演着重要的角色,但过多的无机氮会导致水体恶化进而影响人类健康,生物脱氮技术可高效去除环境中的无机氮且不引起二次污染.随着工程纳米颗粒在生活中的广泛应用,导致其大量释放到土壤及水体中,极大地阻碍了废水处理中的生物脱氮过程,因此,微生物脱氮过程中工程纳米颗粒的毒害作用及减毒措施成了近年来的研究热点...     

纳米颗粒与生物大分子的相互作用及其生物毒性机制

纳米颗粒已得到广泛的应用,同时其潜在的毒性及生物学效应也引起了广泛的关注。许多文献证实纳米颗粒对生物体具有毒性作用,但在分子水平上对其毒性机制的研究较少。本文对近年来纳米颗粒与生物大分子相互作用的最新研究进行了综述,包括纳米颗粒与蛋白质、脂类、核酸等生物分子间的相互作用。     

纳米颗粒对耐冷脱氮菌及其脱氮过程的毒害调控研究进展

生物脱氮具有经济高效、绿色环保的特点,在废水处理中具有广阔前景;目前在废水处理工艺中脱氮效果较好的微生物大部分为嗜温菌,这类菌在低温条件下的脱氮效率会受到强烈抑制,而耐冷脱氮菌可有效抵抗低温环境并进行高效脱氮,逐渐引起了研究者们的重视。其次,纳米颗粒(nanoparticles,NPs)在生物学、农学、医药等领域的应用日渐广泛,但在生产、储存和使用含NPs产品的过程中,不可避免地会向水和土壤环境释放NPs,在水环境中,NPs的大量积累会阻碍微生物的脱氮过程,也对废水处理提出了新的挑战,成为公众日益关注的环境问题和研究热点。当前,有部分研究已关注于耐冷菌的脱氮过程、NPs对耐冷菌脱氮过程的毒害作用及减毒措施。基于此,本篇文章将阐述耐冷菌的耐冷机理与脱氮过程,阐明NPs对耐冷菌脱氮过程的毒害作用与减毒调控措施,为低温环境下采用微生物处理含有NPs的氮污染废水提供理论依据。     

Cu2O纳米颗粒对小麦根系形态及遗传毒性的影响

为了阐明Cu2O纳米颗粒(NPs)暴露对植物根系的毒性效应,本研究以小麦品种'周麦18'为材料,采用水培试验方法,研究了10、50、100和200 mg·L-1浓度的Cu2O-NPs对小麦幼苗生长、根系活性、形态结构及细胞遗传学毒性的影响.结果 表明:不同浓度的Cu2O-NPs降低了小麦幼苗的根芽长度、鲜重、根活性和根...     

纳米银颗粒及纳米二氧化钛颗粒的体外遗传毒性研究

纳米物质以其独特的物理性质广泛用于化妆品、医药和食品工业,但它们的安全性和遗传毒性仍然存在争议.本研究拟采用基于人成淋巴TK6细胞的体外彗星实验整合体外PIG-A基因突变实验对纳米银颗粒(AgNPs)和纳米二氧化钛颗粒(TiO2NPs)的致DNA断裂作用和致突变性进行初步研究.本研究探究了最高至200μmol/L浓度时...     

聚合物纳米颗粒对动脉粥样硬化病变的影响及相关机理研究进展

聚合物纳米颗粒通常指基于疏水性聚合物的纳米粒子,由于其良好的生物相容性、高效的长循环特性以及优于其他纳米颗粒物的代谢排出方式等,在纳米医学领域中得到了广泛关注。现有研究证明聚合物纳米颗粒在心血管疾病,尤其是在动脉粥样硬化(atherosclerosis,AS)的诊断、治疗中具有独特的优点,已经成功地由基础研究向临床应用转化。但是聚合物纳米颗粒引起的炎症反应诱导泡沫细胞形成、巨噬细胞自噬,以及心血管系统疾病力学微环境改变引起的聚合物纳米颗粒富集等,都可能最终诱导AS的发生发展。在此,本文综述了近年来聚合物纳米颗粒在诊断、治疗AS疾病中的应用及其与AS病变的关系和机理,为后续研究利用聚合物纳米颗粒开发新型纳米药物治疗AS提供理论依据。     

金属型纳米颗粒对植物的生态毒理效应研究进展

纳米技术的高速发展和人工纳米颗粒(NPs)的广泛应用带来的潜在环境风险已经引起国内外的广泛关注.金属型纳米颗粒(MB NPs)具有金属毒性和纳米毒性的双重效应,其生物毒性和生态风险已成为纳米毒理学的研究热点之一.植物作为生态系统中的重要组分,是NPs生物累积并进入食物链的潜在途径.本文论述了MB NPs在植物中的吸收、转运和累积过程,总结了MB NPs对植物的毒性效应及其机制,探讨了MB NPs植物毒性的影响因素,综合评述了近年来关于MB NPs对植物特别是农作物的生态毒理效应的研究进展,同时分析了目前研究中存在的问题,对今后的研究方向进行了展望.     

Al2O3纳米颗粒对梨形四膜虫细胞毒性机理研究

采用模式生物梨形四膜虫为研究对象,探讨了Al2O3纳米颗粒对生物细胞的毒性。分别研究了纳米Al2O3对梨形四膜虫生长繁殖、乙酰胆碱酯酶(True choline esterase,TChE)活性、琥珀酸脱氢酶(Succinatedehydrogenase,SDH)活性以及对热激蛋白70(HSP70)和多药耐药(MDR1)基因的表达活性的影响。结果表明:Al2O3纳米颗粒对梨形四膜虫的生长繁殖具有显著的抑制作用,并延长了传代时间,减少了繁殖代数;Al2O3纳米颗粒对梨形四膜虫TChE的活力表现为中低浓度(10 mg/L与100 mg/L)激活,高浓度(500 mg/L)抑制的趋势,而对SDH的活力具有抑制作用,浓度越高作用越明显,尤其在500 mg/L浓度下抑制作用极显著(p<0.01);Al2O3纳米颗粒对梨形四膜虫HSP70及MDR1基因表达均有显著作用,HSP70表现为低浓度抑制、高浓度诱导,而MDR1表现为低浓度诱导、高浓度抑制。可知,Al2O3纳米颗粒对梨形四膜虫是具有毒性的,但是其机制还需要更进一步的研究探索以及验证。     

纳米银对污水生物处理系统的影响

纳米银(silver nanoparticles,Ag-NPs)是目前商业化应用最多的纳米材料,因其优越的抗菌性能,广泛使用于纳米技术强化的消费品。释放到环境中的Ag-NPs随污水收集系统进入市政污水处理厂。市场上Ag-NPs产品日益增多,Ag-NPs与污水处理系统中微生物相互作用,可能影响污水处理厂的运行,引起人们广泛关注。污水中Ag-NPs去向和形态变化具有很大的不确定性。本文总结了Ag-NPs抗菌机制以及污水中Ag-NPs暴露对污水生物处理系统去除有机物、氮、磷等微生物的影响。为了降低Ag-NPs在水环境中的风险,今后需要关注的研究方向,包括:研究不同暴露时长下,Ag-NPs在污水中的形态转变,确定各种形态银的数量,寻求控制或消除Ag-NPs对污水处理系统微生物毒性作用的有效措施,为全面评估水体中Ag-NPs的环境风险提供依据。     

纳米颗粒增强酶生物传感器性能的研究进展

简要介绍生物传感器的原理及分类,并且对纳米颗粒增强酶生物传感器的研究现状进行了评述,尤其是纳米颗粒对葡萄糖生物传感器和尿酸酶生物传感器的增强作用,并对我国生物传感器的发展方向做了展望。     

中华根瘤菌NP1氨单加氧酶基因的克隆与功能鉴定

以中华根瘤菌NP1(Sinorhizobium sp.NP1)为原始菌株,通过同源克隆与Tail-PCR方法,获得1089bp的氨单加氧酶基因(amo)全长序列.该基因编码362个氨基酸,其二级结构与Sinorhizobium meliloti1021AMO的二级结构相似,该蛋白有9个跨膜区段.以自杀穿梭质粒pJQ200SK为原始载体,构建NP1amo基因敲除质粒pJQ200SK-amo-Tc.采用三亲本杂交的方法将该质粒转入原始菌株NP1中,获得amo基因敲除菌株NP1∷amo.通过本贝洛氏(Berthelot)法对氨氮进行测定,发现NP1∷amo的脱氮效率比原始菌株NP1下降约35%.该结果表明,本实验中所克隆的氨单加氧酶基因为脱氮关键酶基因.     

Factors Affecting Nitrous Oxide Production: A Comparison of Biological Nitrogen Removal Processes with Partial and Complete Nitrification

Nitrous oxide (N₂O) emission from biological nitrogen removal (BNR) processes has recently received more research attention. In this study, two lab-scale BNR systems were used to investigate the effects of various operating parameters including the carbon to nitrogen (C/N) ratio, ammonia loading, and the hydraulic retention time on N₂O production. The first system was operated in a conventional BNR mode known as the Ludzack–Ettinger (LE) process, consisting of complete denitrification and nitrification reactors, while the second one was operated in a shortcut BNR (SBNR) mode employing partial nitrification and shortcut denitrification, which requires less oxygen and carbon sources. As the C/N ratio was decreased, a significant increase in N₂O production was observed only in the anoxic reactor of the LE process, indicating that N₂O was released as an intermediate of the denitrification reaction under the carbon-limited condition. However, the SBNR process did not produce significant N₂O even at the lowest C/N ratio of 0.5. When the SBNR process was subjected to increasing concentrations of ammonia, N₂O production from the aerobic reactor was rapidly increased. Furthermore, the increasing production of N₂O was observed mostly in the aerobic reactor of the SBNR process with a decline in hydraulic retention time. These experimental findings indicated that the increase in N₂O production was closely related to the accumulation of free ammonia, which was caused by an abrupt increase of the ammonium loading. Consequently, the partial nitrification was more susceptible to shock loading conditions, resulting in a high production of N₂O, although the SBNR process was more efficient with respect to nitrogen removals as well as carbon and oxygen requirements.     

Optimization of free ammonia concentration for nitrite accumulation in shortcut biological nitrogen removal process

A shortcut biological nitrogen removal (SBNR) utilizes the concept of a direct conversion of ammonium to nitrite and then to nitrogen gas. A successful SBNR requires accumulation of nitrite in the system and inhibition of the activity of nitrite oxidizers. A high concentration of free ammonia (FA) inhibits nitrite oxidizers, but unfortunately decreases the ammonium removal rate as well. Therefore, the optimal range of FA concentration is necessary not only to stabilize nitrite accumulation but also to achieve maximum ammonium removal. In order to derive such optimal FA concentrations, the specific substrate utilization rates of ammonium and nitrite oxidizers were measured. The optimal FA concentration range appeared to be 5–10 mg/L for the adapted sludge. The simulated results from the modified inhibition model expressed by FA and ammonium/nitrite concentrations were shown very similar to the experimental results.     

Mycoendophytes as efficient synthesizers of bionanoparticles: nanoantimicrobials,mechanism, and cytotoxicity

Mycoendophytes are the fungi that occur inside the plant tissues without exerting any negative impact on the host plant. They are most frequently isolated endophytes from the leaf, stem, and root tissues of various plants. Among all fungi, the mycoendophytes as biosynthesizer of noble metal nanoparticles (NPs) are less known. However, some reports showing efficient synthesis of metal nanoparticles, mainly silver nanoparticles and its remarkable antimicrobial activity against bacterial and fungal pathogens of humans and plants. The nanoparticles synthesized from mycoendophytes present stability, polydispersity, and biocompatibility. These are non-toxic to humans and environment, can be gained in an easy and cost-effective manner, have wide applicability and could be explored as promising candidates for a variety of biomedical, pharmaceutical, and agricultural applications. Mycogenic silver nanoparticles have also demonstrated cytotoxic activity against cancer cell lines and may prove to be a promising anticancer agent. The present review focuses on the biological synthesis of metal nanoparticles from mycoendophytes and their application in medicine. In addition, different mechanisms of biosynthesis and activity of nanoparticles on microbial cells, as well as toxicity of these mycogenic metal nanoparticles, have also been discussed.     

Post-treatments of anaerobic effluents

Post-treatments are necessary if anaerobic effluents need to be discharged into surface waters, because anaerobic digestion alone is not able to produce effluents that can meet the discharge standards applied in most industrialized countries, particularly for suspended solids, particulate COD, nitrogen, phosphorus and sulphides. This paper has the aim to present some results obtained in the recent years in our laboratory, where different comprehensive processes that include anaerobic digestion have been studied. Discussion will regard: 1) the ANANOX (ANaerobic-ANoxic-OXic) process for the treatment of municipal wastewater; 2) a process studied for the biological removal of C, N and P from piggery wastewater that has a hybrid anaerobic/anoxic reactor as the first treatment step; 3) the use of a Sequencing Batch Reactor for the post-treatment of digested cheese whey mixed with cheese factory cleaning waters.Abbreviations ABR Anaerobic Baffled Reactor - Bv organic volumetric loading rate (gCOD·L^-1·d^-1) - BV bed volumes - F/M food to microorganism ratio or sludge loading rate (gCOD·g.VSS^-1·d^-1) - HRT hydraulic retention time (t) - JHB University of Johannesburg nutrient removal process - p.e. person equivalent - Qrd recycle for denitrification flow rate - Qrs sludge recycle flow rate - SBR Sequencing Batch Reactor - TKN Total Kjeldahl Nitrogen - VCF Volumetric Concentration Factor (vol. permeate/vol. retentate)     

极端条件下异养硝化-好氧反硝化菌脱氮的研究进展

异养硝化-好氧反硝化(HN-AD)是对传统自养硝化异养反硝化理论的丰富与突破。HN-AD菌在好氧条件下可快速实现氨氮、硝态氮(NO_3~–-N)、亚硝态氮(NO_2~–-N)三氮同步脱除。它们不仅具有分布范围广、适应能力强、代谢通路特殊等特点,而且还具有世代时间短、脱氮速率快、高活性持久等独特优势,在高盐、低温、高氨氮等极端条件表现出了巨大的脱氮潜力,因此在废水生物脱氮领域受到广泛关注。文中在介绍HN-AD菌属类别及代谢机理的基础上,重点总结了在高盐、低温、高氨氮等极端条件下进行氨氮脱除的HN-AD种属,系统分析了它们在极端条件下的脱氮特性及潜力,并简述了HN-AD菌在极端条件下的工艺应用研究进展,最后展望了HN-AD脱氮技术的应用前景和研究方向。