氧化亚铁硫杆菌在制革污泥治理中的应用展望

介绍了氧化亚铁硫杆菌（Thiobacillus ferrooxidans,简称T．f菌）的主要特点以及在不同领域里的应用,并对其在制革污泥治理中的应用情况以及今后研究方向进行了展望。     

混料设计在无花果汁乳酸菌发酵剂配比研究中的应用

为了寻求无花果汁乳酸菌发酵剂中各菌种的最佳组合,采用混料设计法研究了乳酸菌的不同组合对无花果发酵液总活菌数和产酸量的影响,建立了发酵剂中各菌种配比与发酵液总活菌数和产酸量的回归模型,考察了发酵剂中各菌种的互作效应,获得了最佳菌种配比为干酪乳杆菌(Y5-2b)、植物乳杆菌(Yj)和嗜酸乳杆菌(NCFM)1∶1∶2,此时,发酵液总活菌数为1.86×109 CFU/m L,产酸量为7.41 g/L。     

基于产酸能力和高活菌数的益生菌复合菌种发酵技术研究

为了提高益生菌发酵乳的活菌数及发酵过程中的产酸能力,本研究以干酪乳杆菌、嗜酸乳杆菌、双歧杆菌、嗜热链球菌、保加利亚乳杆菌为试验菌种,通过单菌种发酵和复合菌种发酵试验,筛选出最佳的复合菌种组合.试验结果表明:在接种量为5％,接种比例为1∶1,发酵温度为37℃,葡萄糖的添加量为2.5％(质量分数),脱脂乳乳固体质量分数为12％的条件下,干酪乳杆菌和双歧杆菌复合发酵效果最佳,最大滴定酸度可达到328°T,最大活菌数达到2.3×1011 mL-1,与其他菌种组合相比,提高了一个对数级,且在贮藏过程中活菌数下降速度较慢.     

生物沥浸法调理市政污泥研究进展

近年来生物沥浸技术已广泛应用于污水处理厂污泥调理中,但由于市政污泥中存在较高浓度的水溶性有机物(DOM),抑制沥浸中嗜酸性氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans,简称A.f菌)的活性,导致沥浸周期长、污水厂运行成本增加。本文通过文献调研,综述国内外生物沥浸法调理市政污泥影响因素及其研究现状,并对今后的研究重点和方向提出建议和展望,以期为改善我国污水处理厂污泥脱水性能和维持生物沥浸反应器长期稳定运行提供借鉴。     

一株蜡样芽胞杆菌的鉴定及鉴别诊断

我室接收蜡样芽胞杆菌菌种一株,经我室鉴定为蜡样芽胞杆菌?型。现报告如下: 1 将菌种依照GB4789.14—94方法进行鉴定,用标准菌种腊样芽胞杆菌12型和苏云金芽胞杆菌作对照。分别作革兰氏染色、生化反应、小白鼠毒素试验、结晶小体检验,经鉴定该菌种试验结果与蜡样芽胞杆菌标准菌株相同。结果见表1 2 蜡样芽胞杆菌分型鉴定 根据GB4789.14—94蜡样芽胞杆菌生化分型鉴定,此可疑菌种为蜡样芽胞杆菌7型。结果见表2 3 讨论 该菌鉴定一般并不困难,但应注意与     

混料设计法优化红枣汁乳酸发酵菌种配比研究

以红枣发酵液的乳酸含量和活菌数为指标,选择嗜酸乳杆菌(NCFM)、干酪乳杆菌(D400)、植物乳杆菌(121)和嗜热链球菌(St)作为发酵菌种,利用混料设计法优化菌种配比。建立了各菌种配比与发酵液活菌数和乳酸含量的数学回归模型,并对此进行分析和预测,得出各菌种最佳体积比为:干酪乳杆菌(D400)∶嗜酸乳杆菌(NCFM)∶植物乳杆菌(121)=1∶1∶2,此时活菌数为1.81×109 CFU/m L,乳酸含量为6.31 g/L。     

马铃薯乳酸菌饮料发酵菌种研究

为生产出发酵时间短及活菌数高的马铃薯发酵饮料,以保加利亚乳杆菌、嗜热链球菌、干酪乳杆菌、双歧杆菌为试验菌种,以发酵时间和发酵活菌数为评价指标,进行单菌种和复合菌种发酵试验,筛选出最佳的菌种组合。试验结果表明:在接种量5%、各菌种间接种比例均为1:1、发酵温度为40℃的条件下,保加利亚乳杆菌、干酪乳杆菌和双歧杆菌3菌种复合发酵效果最佳,发酵时间为9.5 h,发酵结束时滴定酸度为44.33°T,活菌数达到9.30×10~8 cfu/mL。     

米曲霉“c—a”纯种分离方法的研究

一、前言本试验设想从菌种入手,对“c—a”菌种进行纯种分离,以避免菌种带来的杂菌污染。同时,由于分离后的菌种自身抗性增强、生产性能稳定、生化性能提高,能够在生产过程中形成生长优势,以抵抗杂菌的侵蚀。我们从“c—a”菌种的定向诱变、小试生产选育等过程中发现,米曲霉在分离过程中会出现两种情况: 1.菌落容易过分扩张,影响分离效果; 2.米曲霉的污染菌主要是球菌、芽孢杆菌等杂菌. 因此在这次“c—a”菌的纯种分离过程中,着重加强培养条件的控制。     

多菌种固态发酵去除菜籽粕中的植酸

以普通菜籽粕为原料,选用枯草芽孢杆菌、蜡样芽孢杆菌、植物乳酸菌及酪酸梭状芽孢杆菌多个菌种,通过单菌与混菌发酵,研究发酵对菜籽粕中植酸含量的影响.结果表明,单菌发酵中枯草芽孢杆菌对植酸降解效果优于其他菌种,其降解率可达62.4%;混菌发酵效果优于单菌发酵,当混菌接种量分别为枯草芽孢杆菌6%,蜡样芽孢杆菌4%,植物乳酸菌6%,水料比为1.3:1,pH 6.9,30℃发酵48 h时,菜籽粕植酸含量从2.26%(干基)降至0.221%(干基),降解率达90.15%,粗蛋白含量提高5.19%(干基).     

海水烟气脱硫技术的研究进展

二氧化硫(SO2)是一种对人体健康和大气环境有严重影响的有毒气态污染物,主要释放于煤炭燃烧过程中.海水烟气脱硫技术是一种利用天然海水对SO2直接吸收的方式.文章综述了海水烟气脱硫的原理及工艺流程,并讨论了其影响脱硫效果的因素及改进方式,最后对海水烟气脱硫技术的发展和研究方向提出建议和展望.     

Rapid detection of enterotoxigenic Escherichia coli O6 in water by using monoclonal antibody and a photon-counting television camera

Monoclonal antibodies (MAbs) raised against Escherichia coli O6:H16 were screened against 15 strains of E. coli and 19 non-E. coli bacteria. A MAb-luminescence assay using MAb-5.8, which shows no cross-reactions with non-E. coli bacteria, and a photon-counting television camera were developed for rapid enumeration of E. coli O6:H16 in water. The membrane filter that retained bacteria was boiled for 5 min in a buffer and incubated with biotinylated MAb-5.8. After incubation with streptavidin-peroxidase conjugate, it was reacted with luminol-based reaction mixture. Luminous image and light intensity of the filter was recorded with a Biocell Counter. Levels of E. coli O6 higher than 7 x 10(3) CFU were detected by the MAb-luminescence assay when E. coli O6 was spotted onto the membrane filter. The sample that contained E. coli O6:H16 was filtered through a membrane filter, and the filter that retained bacteria was incubated on a filter paper soaked with nutrient broth supplemented with 0.5% NaCl at 37 degrees C for 6 h. The number of light emission points on the filter correlated well with initial E. coli O6:H16 counts within the range of 1 to 3 x 10(2) CFU. The correlation coefficient was 0.89.     

Real-time PCR detection of bacteria belonging to the Firmicutes Phylum

Members of the bacterial Phylum Firmicutes occupy a wide range of habitats and can be either beneficial or detrimental in diverse settings, including food- and beverage-related industries. Firmicutes are responsible for the vast majority of beer-spoilage incidents and, as such, they have a substantial financial impact in the brewing industry. Rapid detection and identification of a bacterium as a Firmicutes is difficult due to widespread genetic transfer and genome reduction resulting in phenotypic diversity in these bacteria. Here we describe a real-time multiplex PCR to detect and differentiate Firmicutes associated with beer-spoilage from non-Firmicutes bacteria that may be present as benign environmental contaminants. A region of the 16S rRNA gene was identified and predicted to be highly conserved amongst, and essentially specific for, Firmicutes. A real-time PCR assay using a hydrolysis probe targeting this region of the 16S rRNA gene was experimentally shown to detect ten genera of Firmicutes known to be beer spoilers, but does not cross-react with eleven of twelve non-Firmicutes genera which can periodically appear in beer. Only one non-Firmicutes species, Zymomonas mobilis, weakly reacted with the Firmicutes probe. This rPCR assay has a standard curve that is linear over six orders of magnitude of DNA, with a quantitation limit of DNA from <10 bacteria. When used to detect bacteria present in beer, the assay was able to detect 50-100 colony forming units (CFU) of Firmicutes directly from 2.5 cm membranes used to filter 100 ml of contaminated beer. Through incorporation of a 4.7 cm filter and an overnight pre-enrichment incubation, the sensitivity was increased to 2.5-10 CFU per package of beer (341 ml). When multiplexed with a second hydrolysis probe targeting a universal region of the 16S rRNA gene, the assay reliably differentiates between Firmicutes and non-Firmicutes bacteria found in breweries.     

Modeling aerosol formation from alpha-pinene + NOx in the presence of natural sunlight using gas-phase kinetics and gas-particle partitioning theory

A kinetic mechanism was used to link and model the gas-phase reactions and aerosol accumulation resulting from alpha-pinene reactions in the presence of sunlight, ozone (O3), and oxides of nitrogen (NOx). Reaction products and aerosol formation from the kinetic model were compared to outdoor smog chamber experiments conducted under natural sunlight in the presence of NOx and in the dark in the presence of O3. The gas-particle partitioning of semivolatile organics generated in the gas phase was treated as an equilibrium process between particle absorption and desorption. Models vs experimental aerosol yields illustrate that reasonable predictions of secondary aerosol formation are possible from both dark ozone and light NOx/alpha-pinene systems over a variety of different outdoor conditions. On average, measured gas- and particle-phase products accounted for approximately 54-72% of the reacted alpha-pinene carbon. Model predictions suggest that organic nitrates account for another approximately 25% of the reacted carbon, and most of this is in the gas phase. Measured particle-phase products accounted for 60-100% of the particle filter mass, with pinic acid and pinonic acid being the primary aerosol-phase products. In the gas phase, pinonaldehyde and pinonic acid are major products. Model simulations of these and other products show generally reasonable fits to the experimental data from the perspective of timing and concentrations. These results are very encouraging for a compound such as pinonaldehyde, since it is being formed from OH attack on alpha-pinene and is also simultaneously photolyzed and reacted with OH.     

Gas/solid partitioning of semivolatile organic compounds (SOCs) to air filters. 3. An analysis of gas adsorption artifacts in measurements of atmospheric SOCs and organic carbon (OC). WHen using teflon membrane filters and quartz fiber filters

Adsorption of gaseous semivolatile organic compounds (SOCs) onto the filter(s) of a filter/sorbent sampler is a potential source of measurement error when determining specific SOCs as well as organic carbon (OC) levels in the atmosphere. This work examines partitioning to both Teflon membrane filters (TMFs) and quartz fiber filters (QFFs) for purposes of predicting the magnitude of the compound-dependent gas adsorption artifact as a function of various sampling parameters. The examination is based on values of Kp,face (m3 cm(-2)), the gas/filter partition coefficient expressed as [ng sorbed per cm2 of filter face]/[ng per m3 in the gas phase]. Values of Kp,face were calculated based on literature values of the gas/solid partition coefficient Kp,s [ng sorbed per m2 of filter]/[ng per m3 in gas phase] for the adsorption of various polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzodioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) to TMFs, and for the adsorption of PAHs to QFFs. At relative humidity (RH) values below approximately 50%, the Kp,face values for PAHs are lower on TMFs than on ambient-backup QFFs. The gas adsorption artifact will therefore be lower for PAHs with TMFs than with QFFs under these conditions. In the past, corrections for the gas/filter adsorption artifact have been made by using a backup filter, and subtracting the mass amount of each compound found on the backup filter from the total (particle phase + sorbed on filter) amount found on the front filter. This procedure assumes that the ng cm(-2) amounts of each SOC sorbed on the front and backup filters are equal. That assumption will only be valid after both filters have reached equilibrium with each of the gaseous SOCs in the incoming sample air. The front filter will reach equilibrium first. The minimum air sample volume Vmin,f+b required to reach gas/filter sorption equilibrium with a pair of filters is 2Kp,face Afilter where Afilter (cm2) is the per-filter face area. Kp,face values, and therefore Vmin,f+b values, depend on the compound, relative humidity (RH), temperature, and filter type. Compound-dependent Vmin,f+b values are presented for PAHs and PCDD/Fs on both TMFs and QFFs. Compound-dependent equations which give the magnitude of the filter adsorption artifact are presented for a range of different sampling arrangements and circumstances. The equations are not intended for use in actually correcting field data because of uncertainties in actual field values of relevant parameters such as the compound-dependent Kp,face and gas/particle Kp values, and because of the fact that the equations assume ideal step-function chromatographic movement of gas-phase compounds through the adsorbing filter. Rather, the main utility of the equations is as guidance tools in designing field sampling efforts that utilize filter/sorbent samplers and in evaluating prior work. The results indicate that some backup-filter-based corrections described in the literature were carried out using sample volumes that were too small to allow proper correction for the gas adsorption artifactfor some specific SOCs of interest. Similar conclusions are reached regarding artifacts associated with the measurement of gaseous and particulate OC.     

Sustainable colloidal-silver-impregnated ceramic filter for point-of-use water treatment

Cylindrical colloidal-silver-impregnated ceramic filters for household (point-of-use) water treatment were manufactured and tested for performance in the laboratory with respect to flow rate and bacteria transport. Filters were manufactured by combining clay-rich soil with water, grog (previously fired clay), and flour, pressing them into cylinders, and firing them at 900 degrees C for 8 h. The pore-size distribution of the resulting ceramic filters was quantified by mercury porosimetry. Colloidal silver was applied to filters in different quantities and ways (dipping and painting). Filters were also tested without any colloidal-silver application. Hydraulic conductivity of the filters was quantified using changing-head permeability tests. [3H]H2O water was used as a conservative tracer to quantify advection velocities and the coefficient of hydrodynamic dispersion. Escherichia coli (E. coli) was used to quantify bacterial transport through the filters. Hydraulic conductivity and pore-size distribution varied with filter composition; hydraulic conductivities were on the order of 10(-5) cm/s and more than 50% of the pores for each filter had diameters ranging from 0.02 to 15 microm. The filters removed between 97.8% and 100% of the applied bacteria; colloidal-silver treatments improved filter performance, presumably by deactivation of bacteria. The quantity of colloidal silver applied per filter was more important to bacteria removal than the method of application. Silver concentrations in effluent filter water were initially greater than 0.1 mg/L, but dropped below this value after 200 min of continuous operation. These results indicate that colloidal-silver-impregnated ceramic filters, which can be made using primarily local materials and labor, show promise as an effective and sustainable point-of-use water treatment technology for the world's poorest communities.     

Effects of sampling artifacts on occupational samples of diesel particulate matter

Total carbon (TC) is sometimes used to measure or characterize diesel particulate matter (DPM) in occupational settings such as underground mines. DPM samples are collected on quartz fiber filters. When using quartz fiber filters, adsorption of gas phase organic carbon (OC) has been reported, causing a positive bias in the particulate TC results (adsorption artifact). Most of the data on the sampling artifacts and corrections applyto environmental air sampling, where samples are collected at a much higher filter face velocity and the OC concentrations are generally much lower relative to occupational sampling. In this study, we investigated the effects of adsorption artifact on samples from occupational settings. Samples were collected with and without denuders to determine the amount of gas phase OC collected and the accuracy of certain corrections. In underground stone mines, the adsorption artifact was found to positively bias the particulate TC by greater than 20% for filter loadings below 25 microg/cm2 TC (8-h time weighted average = 262 microg/m3). The tandem filter correction reduced the effect of the artifact, as high as 60% of the TC value, to less than 11% for laboratory data. It also significantly reduced the effect of the artifact obtained for field samples.     

Antimicrobial effect of silver particles on bacterial contamination of activated carbon fibers

Even though activated carbon fiber (ACF) filters have been widely used in air cleaning for the removal of hazardous gaseous pollutants, because of their extended surface area and high adsorption capacity, bacteria may breed on the ACF filters as a result of their good biocompatibility; ACF filters can themselves become a source of bioaerosols. In this study, silver particles were coated onto an ACF filter, using an electroless deposition method and their efficacy for bioaerosol removal was tested. First, various surface analyses, including scanning electron microscopy, inductively coupled plasma and X-ray diffraction were carried out to characterize the prepared ACF filters. Filtration and antimicrobial tests were then performed on the filters. The results showed that the silver-deposited ACF filters were effective for the removal of bioaerosols by inhibition of the survival of microorganisms, whereas pristine ACF filters were not. Two bacteria, Bacillus subtilis and Escherichia coli, were completely inhibited within 10 and 60 min, respectively. Electroless silver deposition did not influence the physical characteristics of ACF filters such as pressure drop and filtration efficiency. The gas adsorptive ability of the silver-deposited ACF filter, as represented by the micropore specific surface area, decreased by about 20% compared to the pristine filter because of the blockage of the ACF micropores by silver particles. Therefore, the amount of silver particles on the ACF filters needs to be optimized to avoid excessive reduction of their adsorptive characteristics and to show effective antimicrobial activity.     

Pathways of sulfide oxidation by haloalkaliphilic bacteria in limited-oxygen gas lift bioreactors

Physicochemical processes, such as the Lo-cat and Amine-Claus process, are commonly used to remove hydrogen sulfide from hydrocarbon gas streams such as landfill gas, natural gas, and synthesis gas. Biodesulfurization offers environmental advantages, but still requires optimization and more insight in the reaction pathways and kinetics. We carried out experiments with gas lift bioreactors inoculated with haloalkaliphilic sulfide-oxidizing bacteria. At oxygen-limiting levels, that is, below an O(2)/H(2)S mole ratio of 1, sulfide was oxidized to elemental sulfur and sulfate. We propose that the bacteria reduce NAD(+) without direct transfer of electrons to oxygen and that this is most likely the main route for oxidizing sulfide to elemental sulfur which is subsequently oxidized to sulfate in oxygen-limited bioreactors. We call this pathway the limited oxygen route (LOR). Biomass growth under these conditions is significantly lower than at higher oxygen levels. These findings emphasize the importance of accurate process control. This work also identifies a need for studies exploring similar pathways in other sulfide oxidizers such as Thiobacillus bacteria.     

Electrostatic sampler for semivolatile aerosols: chemical artifacts

Electrostatic precipitators (ESPs) show promise as an alternative sampling method for semivolatile aerosols because they are less susceptible to adsorptive and evaporative artifacts than filter based methods. However, the corona discharge may after the chemical composition of a sampled aerosol. Chemical artifacts associated with electrostatic precipitation of semivolatile aerosols were investigated in the laboratory. ESPs and filters sampled both particles and vapors of alkanes, polycyclic aromatic hydrocarbons, and alkenes across varying concentrations. Gravimetric measurements between the two sampling methods were well correlated. Ozone generated by the ESP corona was the primary cause of alkene reactions in the gas phase. Particles collected within the corona region were vulnerable to irradiation by corona ions overtime. Particles collected outside the corona region did not react. Vapors passing through the corona reacted to a lesser extent. Vapors captured after passing through the ESP reacted with ozone that was not removed by the vapor trap. Chemical speciation of highly reactive compounds (i.e., alkenes or other compounds with relatively short half-lives outdoors) is not appropriate with ESPs. Electrostatic precipitation of these compounds is appropriate, however, when total organic carbon is of interest as the ESP does not alter the amount of mass measured gravimetrically. ESPs can make accurate measurements of more persistent semivolatile compounds, such as alkanes and PAHs.     

毛细管气相色谱法测定番茄中的非挥发性有机酸、高级脂肪酸和低分子量糖类

本文提出了应用毛细管气相色谱法(CGC)对番茄内的非挥发性有机酸、高级脂肪酸和低分子量糖类进行测定的方法。番茄样品经匀浆后用水在超声波振荡下提取,减压干燥后, 用羟胺吡啶(2.5mg/ml)先将糖转化为肟,再用硅烷化试剂(BSTFA+1%TMCS)衍生化,然后进行毛细管气相色谱分析。有机酸的测定采取将番茄样品加入H2SO4-CH3OH(10%) 30ml衍生化2h,经萃取、干燥后再进行毛细管气相色谱分析。针对方法的前处理条件、重现性及回收率均进行了探讨。结果显示番茄中糖类主要含有葡萄糖、果糖,酸类主要包括柠檬酸、苹果酸、棕榈酸。此外, 对比不同品种的番茄样品中糖及有机酸含量成分进行了营养对比实验。