化学消毒的中和剂对水中内毒素活性检测的影响

本研究选取化学消毒的常用6种中和剂组氨酸、甘氨酸、抗坏血酸、吐温80、亚硫酸钠和硫代硫酸钠,采用动态浊度鲎试验定量检测样品中内毒素活性,研究中和剂在不同浓度范围内单独使用对内毒素活性检测的影响,旨在优选出适于鲎法检测细菌内毒素的中和剂种类,确定合适的浓度范围.结果表明在0~1.0%浓度范围内,除了甘氨酸和硫代硫酸钠之外,组氨酸、抗坏血酸、吐温80、亚硫酸钠(碱性和中性)均对鲎试验结果有不同程度的干扰,都不能在鲎试验之前作为化学消毒的中和剂.虽然0~1.0%浓度的甘氨酸对鲎试验结果基本无明显影响,但是甘氨酸和戊二醛的中和产物显黄色,所以不适于在光度法鲎试验中用作戊二醛的中和剂.0~1.0%浓度的硫代硫酸钠对鲎试验结果基本无明显干扰,但是当浓度升高至1.0%~5.0%时会对鲎试验结果有一定的抑制作用.与组氨酸、甘氨酸、抗坏血酸、吐温80和亚硫酸钠相比,硫代硫酸钠更适于在内毒素活性检测之前用作消毒剂的中和剂,但是浓度应控制在0.5%范围以内.     

Effect of tracer dyes on initial deposits and persistence of bacillus thuringiensis subsp. kurstaki toxin after application of two commercial formulations onto spruce trees

Abstract

The effect of two tracer dyes [Erio Acid Red (EAR) and Acid Black 48 (AB‐48)] on initial deposits and persistence of Bacillus thuringiensis subsp. kurstaki (Btk) toxin (delta‐endotoxin) was studied after spraying two commercial formulations, Foray® 48B and Foray® 76B, over potted white spruce [Picea glauca (Moench) Voss] seedlings, at a dosage rate of 30 billion international units (BIU) per ha. Spray was applied using a spinning disc atomizer calibrated to deliver droplet sizes similar to those utilized in ultra‐low‐volume (ULV) treatments in operational insect control programs. The sprayed seedlings were left outdoors at the Sault Ste. Marie laboratory for 18 days under natural conditions of sunlight, wind and rainfall. Initial deposits and persistence of delta‐endotoxin protein in spruce foliage were determined by immunoassay [enzyme linked immunosorbent assay (ELISA)] quantification of the delta‐endotoxin. The total protein (inactive plus active) and delta‐endotoxin (active protein) concentrations in the two formulations were determined by a gravimetric procedure and by ELISA respectively.

The initial deposit levels of the toxin on foliage were not markedly affected by the addition of either of the two tracer dyes, and showed only a narrow range of 1521 to 1625 ng/g foliage (fresh weight) for Foray 48B, and 1789 to 2056 ng/g for Foray 76B. However, the persistence of the toxin was significantly influenced by the presence of the dyes. The toxin persisted in foliage only for 7 d post‐spray When the EAR dye was added to Foray 48B, compared to 10 d when no dye was added. The average half‐life (DT₅₀) of disappearance was 17.4 h for Foray 48B with EAR, and 20.9 h when no dye was present. In contrast, the situation was reversed in Foray 76B, since the duration of persistence was 10 d when EAR was added to Foray 76B, compared to 7 d when no dye was added. The average DT₅₀ was 27.9 h for Foray 76B with EAR, and 22.2 h without the dye. Persistence was the longest (14 d) when the AB‐48 dye was added to Foray 76B, and the DT₅₀ was 44.9 h.     

饮用水细菌内毒素污染的风险识别与分析研究进展

细菌内毒素,又称脂多糖分子或者热原,是革兰氏阴性细菌和某些蓝藻细胞壁组分,主要由菌体死亡解体后释放.内毒素是常见的外源性致热原,属于强免疫刺激剂,与多种人类疾病密切相关.由于饮用水中会滋长微生物,因此内毒素污染在饮用水中普遍存在.近年来,国外研究中饮用水的细菌内毒素污染开始受到关注,成为饮用水微生物安全领域新兴的研究方向.本文概述了细菌内毒素的物化性质和生物活性,分析了细菌内毒素在饮用水中的存在形态,综述了国内外关于地表水源、地下水源、管网末梢水和深度处理水的内毒素污染调查状况,分析了传统水处理技术、深度处理技术和饮用水消毒技术对内毒素的控制效果,探讨了饮用水中内毒素的血液暴露、呼吸暴露和胃肠暴露途径导致机体潜在的健康风险、安全阈值和相关标准,并对饮用水细菌内毒素污染研究方向进行了展望.     

Dioxin alters inflammatory responses to lipopolysaccharide

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) has well characterized effects on specific immune responses, but the effects on the innate immune system are less understood. The effect of TCDD on inflammatory responses induced by lipopolysaccharide (LPS) was evaluated in C57BL/6J female mice. Mice were treated with 30?µg?kg^?1 TCDD or vehicle once, p.o., and 4 days later, animals received LPS (0.05?×?10⁷?EU?kg^?1, i.p.) or vehicle. Inflammatory mediators and the liver injury marker, alanine aminotransferase (ALT), were measured, and liver histology was evaluated. TCDD-treated animals had higher plasma ALT activity than vehicle-treated animals, but the effect was mild and time-dependent. Few changes in liver histopathology were observed, mainly represented in greater steatosis in TCDD/LPS-treated mice compared to mice treated with LPS or TCDD alone. LPS produced a time-dependent increase in the plasma concentrations of interleukins (IL)-6, -10, and -12 and interferon (IFN)-γ, tumor necrosis factor (TNF)-α, and monocyte chemoattractant protein (MCP)-1. With the exception of IL-12, concentrations of each of these mediators were higher in plasma of mice co-treated with TCDD and LPS compared to either agent alone. The dose–response curve for the concentration of IL-6 in plasma suggested that dioxin increased the potency of LPS to cause the release of this cytokine but not the maximal response. Co-treatment with TCDD and LPS also led to greater expression of mRNA for IL-10 and IFN-γ compared to either TCDD or LPS alone. These results suggest that TCDD changes the inflammatory cytokine profile induced by LPS and that LPS enhances the hepatic steatotic response to TCDD.     

Comparison of four methods for the extraction of lipopolysaccharide from cyanobacteria

Four procedures were compared for the extraction of lipopolysaccharide (LPS) from 10 laboratory strains of cyanobacteria. LPS yields as a percentage of cyanobacterial dry weight ranged from 0.03 to 6.13. The heterotrophic bacterial LPS marker 2-keto-3-deoxyoctonoic (KDO) acid was not detectable in any of the cyanobacterial LPS preparations. All methods yielded LPS that contained biologically- and toxicologically-significant quantities of the cyanotoxin microcystin, when applied to some, but not all, microcystin-producing cyanobacterial strains. Of the four methods used, a procedure including Proteinase K, plus RNase and DNase, performed best overall on the basis of minimum time required, higher percentage yields of LPS, and minimal co-extraction of microcystin.     

Sorptive interactions and binding of δ‐endotoxin protein from bacillus thuringiensis subsp. kurstaki inforest soils

Abstract

The adsorption, desorption and binding of the insecticidal protein from Bacillus thuringiensis subsp. kurstaki (Btk toxin) onto autoclaved sandy and clay loam forest soils were studied at 23°C in a buffer medium (pH 10.2) using the precipitated protein mixture (active + inactive) obtained from a commercial Btk formulation. The active protein in the buffer solution was quantified by ELISA technique. Maximum adsorption of the toxin onto the sandy (301 μg/g) and clay (474 μg/g) loam soils was found to occur after 3 and 4 hours of agitation, respectively. Adsorption of the toxin was higher in the clay loam soil than in sandy loam. Adsorption parameters were calculated using the Freundlich and linear isotherm equations. The K_F and 1/n values for the soils were 1.12 and 1.48 (sandy), and 20.42 and 0.874 (clay), respectively, indicating stronger affinity of the toxin for the clay compared to the sandy loam soil. The linear model showed deviations at higher concentrations, nevertheless using the best fit, K_D and K_OC values were computed for the two soils. For sandy loam, the K_D and K_OC values were 9.38 and 391, respectively; the corresponding values for clay loam were 13.19 and 425, confirming the higher sorption affinity of the toxin for clay loam. The adsorption data did not fit the Langmuir equation because of heterogeneity of the soil surface. Desorption studies showed that more than half of the adsorbed toxic protein remained firmly attached to sandy (162.6 μg/g or 54.5%) and clay (314.0 μg/g or 67.4%) loam soils after six 0.5‐h washes (total 3.0 h wash time). Although the toxin appears to be a non‐leacher, its lateral mobility, soil persistence and biological consequences, including bioavailability of the bound residues, are poorly understood and require further investigation.     

北京自备井水源内毒素污染及与其他水质参数的相关分析

本研究采集驻京部队14个自备井水源样品,采用动态浊度东方鲎试验定量检测内毒素活性,同时检测了细菌总数(流式细胞术法)、异养菌平板计数(HPC)、菌落总数(平板法)、总大肠菌群、颗粒物特征、浊度、溶解性有机碳(DOC)和UV254值,比较了内毒素与这些水质参数的相关性.结果表明自备井水源的总内毒素活性为0.15~13.20 EU·m L~(-1),其中游离态内毒素活性为0.10~5.29 EU·m L~(~(-1)),结合态内毒素活性为0.01~8.60 EU·m L~(-1).对于内毒素污染较严重的自备井水源来说,结合态内毒素所占比例明显高于游离态内毒素.总内毒素与其他水质参数关联顺序为细菌总数(流式细胞术法)(r=0.88)HPC(r=0.79)DOC(r=0.77)UV254(r=0.57)总大肠菌群(r=0.50)菌落总数-平板法(r=0.49)=浊度(r=0.49)颗粒物总数(r=0.41).结合态内毒素与其他水质参数关联顺序为细菌总数-流式细胞术法(r=0.81)HPC(r=0.66)总大肠菌群(r=0.65)浊度(r=0.62)颗粒物总数(r=0.58)菌落总数(平板法)(r=0.22).游离态内毒素与水中DOC、UV254的相关系数r分别为0.58和0.26,结果表明游离态内毒素与水中DOC的相关性较大,与UV254相关性很小.     

水中细菌内毒素污染特性及检测方法研究进展

细菌内毒素是革兰氏阴性菌和某些蓝藻细胞壁的脂多糖复合物,主要由菌体死亡解体后释放,是常见的外源性致热原,具有强免疫刺激能力,与人类多种疾病密切相关.内毒素分子的耐受力好,耐热性强,不易被常规方法去除.饮用水和水环境中的内毒素可通过多种暴露途径导致机体潜在的健康风险,成为近年来研究的热点.本文概述了细菌内毒素的理化特性和生物活性,综述了细菌内毒素多种检测方法的研究进展,并对细菌内毒素的法定检测方法——鲎试验用于检测水体环境样品的干扰问题和排除方法进行分析.     

水体环境内毒素活性的鲎法定量检测及影响因素研究

内毒素是革兰氏阴性菌和某些蓝藻细胞壁上的脂多糖复合物,是常见的外源性致热原,具有强免疫刺激能力,与人类多种疾病密切相关.本研究采用最低检测限为0.03 EU.mL-1的动态浊度东方鲎(Tachypleus Amebocyte Lysate,TAL)试剂,对不同水体环境样品的内毒素活性定量检测,分析了pH值和无机盐对TAL试验检测结果的影响.结果表明pH值在6.0～8.4范围内适合进行内毒素检测,过酸条件引起检测结果的抑制,过碱条件引起检测结果的增强,检测前可用无热原Tris-HCl(pH=7.4)溶液调节pH.当NaCl、Na2SO4、CaCl2、MgCl2和KCl浓度小于50 mg.L-1时不会干扰内毒素的检测,当浓度升高至1 000～10 000 mg.L-1时引起抑制效果.浓度为2.5 mg.L-1的FeCl3、Fe2(SO4)3、AlCl3和Al2(SO4)3即可以引起强烈抑制效果,内毒素活性的实测值已经严重偏离实际值.采用动态浊度TAL试验检测超纯水、自来水和景观用水的内毒素活性,结果表明所检测的超纯水的内毒素活性<0.06 EU.mL-1,自来水的内毒素活性为0.46 EU.mL-1,景观用水的内毒素活性为432.68EU·mL-1.     

Comparison of endotoxin levels and gram-negative bacteria under different conditions in microbial laboratories and a biowaste site

In this study, we assessed airborne endotoxin levels in university laboratories, hospital diagnostic laboratories, and a biowaste site. We also investigated indoor and outdoor sampling, sampling site, type of ventilation system, presence of open biowaste boxes, weather, and detection of Gram-negative bacteria (GNB). A total of 69 air samples were collected from 11 facilities in three institutions. Average total airborne endotoxin levels ranged from <0.01 to 10.02 EU m⁻³, with an overall mean of 1.03 EU m⁻³. Endotoxin levels were high in window-ventilated facilities, in facilities in which GNB were detected; levels were also high when it was rainy (all ps < 0.05). Endotoxin levels were significantly correlated with humidity (r = 0.70, p < 0.01). The presence of HVAC; humidity; and the presence of open biowaste boxes affect endotoxin levels in laboratories.