城市生活垃圾的微生物处理技术

城市生活垃圾量的日益增多严重威胁着城市的环境及人们的健康,垃圾处理成为现代社会面临的重要问题之一,因此城市生活垃圾处理技术对于城市的可持续发展起着非常重要的作用。微生物在自然界中种类繁多,在城市生活垃圾生物处理应用中占有重要地位。本文对微生物在城市生活垃圾的卫生填埋技术、生物反应器填埋技术、好氧堆肥技术、发酵降解技术及生物干燥器技术中的应用进行了综述,并对城市生活垃圾的综合处理提出建议,以期为城市生活垃圾的微生物处理技术的应用提供参考。     

Model of the Fate of Chemicals in Sludge-Amended Soils with Uptake in Vegetation and Soil-Dwelling Organisms

The BASL4 (Biosolids Amended Soil Level 4) soil biota models are described, applied, and discussed. The models simulate the fate of organic chemicals present in biosolids that are applied to a two-layer soil and address the processes of chemical degradation, volatilization, leaching, and sorption to decaying organic matter. Uptake in invertebrates (worms), small mammals (shrews), and vegetation is simulated involving three levels of complexity, namely simple equilibrium partitioning, steady state bioaccumulation and dynamic bioaccumulation models. A simulation of the fate of pyrene is presented to illustrate the model's capabilities. The model is successfully applied to the fate of triclosan in biosolids giving results in accord with monitoring data. The model results suggest that triclosan may biomagnify in a terrestrial food web. It is believed that the model is useful for assessing the bio-uptake of chemicals associated with biosolids, thus providing guidance on expected levels of contamination and the associated risks to wildlife.     

Microbiological Production of Gibberellic Acid in Glucose Media

Gibberellic acid production from various substrates was studied in 43 strains of Fusarium, among which F. moniliforme strain IOC-3326 was selected as the best producer. Experiments were carried out in shaker flasks and pilot plant fermentors. The results indicate that the best substrate for gibberellic acid production with this strain is composed of the following: glucose, 20 g; corn steep liquor, 25 g; ammonium nitrate, 2.6 g; monopotassium phosphate, 0.5 g; potassium sulfate, 0.2 g; and water, 1000 ml. Glucose, ammonium nitrate, and corn steep liquor were found to be critical. With this medium, maximal yields of 1196 mg per liter in shaker flasks and 997 mg per liter in fermentors were produced.     

The New Face of the Lipid Droplet: Lipid Droplet Proteins

The lipid droplet (LD) is an organelle with vital functions found in nearly all organisms. LD proteomic research has provided fundamentally important insights into this organelle's functions. The review provides a summary of LD proteomic studies conducted across diverse organisms and cell and tissue types. The accumulated proteomic data are reviewed for evidence of a protein targeting mechanism for the organelle. The hypotheses for several specific localization mechanisms based on what is known about targeting mechanisms for other organelles and vesicles are provided. Although the nature of the mechanism is not known, the functional data demonstrate that the targeting mechanism and, indeed, the organelle itself, is conserved from prokaryotes to eukaryotes. It is hoped that the review will help inspire further research leading to novel discoveries in the field.     

Estimating a Treatment Effect in Residual Time Quantiles Under the Additive Hazards Model

For randomized clinical trials where the endpoint of interest is a time-to-event subject to censoring, estimating the treatment effect has mostly focused on the hazard ratio from the Cox proportional hazards model. Since the model’s proportional hazards assumption is not always satisfied, a useful alternative, the so-called additive hazards model, may instead be used to estimate a treatment effect on the difference of hazard functions. Still, the hazards difference may be difficult to grasp intuitively, particularly in a clinical setting of, e.g., patient counseling, or resource planning. In this paper, we study the quantiles of a covariate’s conditional survival function in the additive hazards model. Specifically, we estimate the residual time quantiles, i.e., the quantiles of survival times remaining at a given time t, conditional on the survival times greater than t, for a specific covariate in the additive hazards model. We use the estimates to translate the hazards difference into the difference in residual time quantiles, which allows a more direct clinical interpretation. We determine the asymptotic properties, assess the performance via Monte-Carlo simulations, and demonstrate the use of residual time quantiles in two real randomized clinical trials.     

Fate of Residual Lignin during Delignification of Kraft Pulp by Trametes versicolor

The fungus Trametes versicolor can delignify and brighten kraft pulps. To better understand the mechanism of this biological bleaching and the by-products formed, I traced the transformation of pulp lignin during treatment with the fungus. Hardwood and softwood kraft pulps containing ¹⁴C-labelled residual lignin were prepared by laboratory pulping of lignin-labelled aspen and spruce wood and then incubated with T. versicolor. After initially polymerizing the lignin, the fungus depolymerized it to alkali-extractable forms and then to soluble forms. Most of the labelled carbon accumulated in the water-soluble pool. The extractable and soluble products were oligomeric; single-ring aromatic products were not detected. The mineralization of the lignin carbon to CO₂ varied between experiments, up to 22% in the most vigorous cultures. The activities of the known enzymes laccase and manganese peroxidase did not account for all of the lignin degradation that took place in the T. versicolor cultures. This fungus may produce additional enzymes that could be useful in enzyme bleaching systems.     

The Relevance of the Distribution of Micro-organisms Within Batches of Food to the Control of Microbiological Hazards from Foods

The distribution of micro-organisms within batches of food is identified as log-normal and this distribution has practical implications in the control of microbial hazards in foods. These implications are explained as effects upon counting procedures, changes in levels through processes, detection of low levels of micro-organisms, the use of indicator groups, presence/absence tests, consumer safety calculations, and sample unit size analysed.     

The Practical Significance in the Microbiological Examination of Cold Stored Foods of the Allegedly Low Heat Resistance among Psychrotrophic Organisms

Summary: The significance in food microbiology of the observation of Stapert, Sokolski & Northam (1962), that some bacteria occurring in water have such low heat resistances that they would be affected by the warm agar used for pouring plates, was tested. Forty-two samples of 6 different foods stored for 7 days at 3° to enrich their psychrotrophic microflora, were examined using the same medium, but in thin poured plates and on spread plates, respectively, incubated at 14°. The logarithmic average count of the foods was c. 10⁸/g and included about 60% Gram-negative rods and 30% cocci. In 90% of the samples no differences were observed between the results from the two methods of counting. The slightly higher spread plate counts in the remaining instances could be accounted for by the increased disruption of bacterial agglomerations always observed in this procedure. Hence there is no reason to query the results of poured plate counts in general. Where it is yet probably safer to use spread plates, rigorous asepsis in pouring and storing should be observed to prevent the development of colonies of contaminants too small to be detected when the plates are inoculated, but leading to erroneous counts after incubation.     

氨基酸生产和海洋生物的氨基酸资源开发

氨基酸在医药、食品、饲料等领域有着极为重要和广泛的用途,世界上氨基酸总需求量以５～１０％递增,市场竞争十分激烈。生物资源提取、化学合成、生物合成和综合法是生产氨基酸的４种技术,目前的发展趋势为生物合成和综合法,特别是将现代生物工程技术应用于氨基酸生产。另外,氨基酸生产领域另一个新的倾向是海洋生物氨基酸资源的开发和应用,尤其是海洋生物所产生的特殊氨基酸、肽及其衍生物的开发,同时,综合利用海产品加工后的废弃物来生产氨基酸也受到重视。     

Microbiological Evaluation of Household Drinking Water Treatment in Rural China Shows Benefits of Electric Kettles: A Cross-Sectional Study

Background

In rural China ~607 million people drink boiled water, yet little is known about prevailing household water treatment (HWT) methods or their effectiveness. Boiling, the most common HWT method globally, is microbiologically effective, but household air pollution (HAP) from burning solid fuels causes cardiovascular and respiratory disease, and black carbon emissions exacerbate climate change. Boiled water is also easily re-contaminated. Our study was designed to identify the HWT methods used in rural China and to evaluate their effectiveness.

Methods

We used a geographically stratified cross-sectional design in rural Guangxi Province to collect survey data from 450 households in the summer of 2013. Household drinking water samples were collected and assayed for Thermotolerant Coliforms (TTC), and physicochemical analyses were conducted for village drinking water sources. In the winter of 2013–2104, we surveyed 120 additional households and used remote sensors to corroborate self-reported boiling data.

Findings

Our HWT prevalence estimates were: 27.1% boiling with electric kettles, 20.3% boiling with pots, 34.4% purchasing bottled water, and 18.2% drinking untreated water (for these analyses we treated bottled water as a HWT method). Households using electric kettles had the lowest concentrations of TTC (73% lower than households drinking untreated water). Multilevel mixed-effects regression analyses showed that electric kettles were associated with the largest Log₁₀TTC reduction (-0.60, p<0.001), followed by bottled water (-0.45, p<0.001) and pots (-0.44, p<0.01). Compared to households drinking untreated water, electric kettle users also had the lowest risk of having TTC detected in their drinking water (risk ratio, RR = 0.49, 0.34–0.70, p<0.001), followed by bottled water users (RR = 0.70, 0.53–0.93, p<0.05) and households boiling with pots (RR = 0.74, 0.54–1.02, p = 0.06).

Conclusion

As far as we are aware, this is the first HWT-focused study in China, and the first to quantify the comparative advantage of boiling with electric kettles over pots. Our results suggest that electric kettles could be used to rapidly expand safe drinking water access and reduce HAP exposure in rural China.     

Development and Testing of a Microbiological Assay To Detect Residual Effects of Disinfectant on Hard Surfaces

We describe a glucuronidase bioassay for detecting residual bactericidal activity from the use of disinfectants on hard surfaces; in this assay we used formaldehyde, ethanol, isopropanol, chlorine, and a commercial preparation containing 2-bromo-2-nitro-1,3-propanediol. Chlorine and the commercial preparation showed bactericidal activity (53.5% and 98.2%, respectively) for a week after disinfection.     

Sulfate Reduction Relative to Methane Production in High-Rate Anaerobic Digestion: Microbiological Aspects

In the high-rate anaerobic reactors studied (ca. 10 g of chemical oxygen demand [COD] removed per liter of reactor per day), the sulfate-reducing bacteria (SRB) were poor competitors of methane-producing bacteria (MPB), scavenging only on the order of 10 to 20% of the total electron flow. The relatively noncompetitive nature of the SRB in this type of reactor is in sharp contrast to the tendency of the SRB to dominate in natural environments and in other types of anaerobic digesters. Various factors such as the feedback inhibition of H₂S on the SRB, iron limitation, the origin of the SRB inocula, biokinetics, and thermodynamics were investigated. The outcome of the SRB-MPB competition under the reactor conditions studied appeared to be particularly determined by two factors. The SRB, as predicted by the V_max-K_m kinetics, competed most effectively at low substrate levels (<0.5 g of COD per liter). The MPB, however, appeared to colonize and adhere much more effectively to the polyurethane carrier matrix present in the reactor, thus compensating for the apparent lower growth rates. Even if the reactor was initially allowed to be predominantly colonized by SRB, the MPB could regain dominance.     

家庭生态农场的氮素营养生产分析

引言土地的沙漠化也许是人类文明进程所付出的最沉重代价。我国北方干旱地区是一个巨大的潜在“沙漠化温床”,巳沙化土地达3.34×