Wind, rain and bacteria: The effect of weather on the microbial composition of roof-harvested rainwater

The microbiological and chemical quality of tank-stored rainwater is impacted directly by roof catchment and subsequent run-off contamination, via direct depositions by birds and small mammals, decay of accumulated organic debris, and atmospheric deposition of airborne micro-organisms and chemical pollutants. Previous literature reports on roof water quality have given little consideration to the relative significance of airborne micro-organisms. This study involved analyses of direct roof run-off at an urban housing development in Newcastle, on the east coast of Australia. A total of 77 samples were collected during 11 separate rainfall events, and microbial counts and mean concentrations of several ionic contaminants were matched to climatic data corresponding to each of the monitored events. Conditions both antecedent to, and those prevailing during each event, were examined to investigate the influence of certain meteorological parameters on the bacterial composition of the roof water and indirectly assess the relative contribution of airborne micro-organisms to the total bacterial load. Results indicated that airborne micro-organisms represented a significant contribution to the bacterial load of roof water at this site, and that the overall contaminant load was influenced by wind velocities, while the profile (composition) of the load varied with wind direction. The implications of these findings to the issues of tank water quality and health risk analysis, appropriate usage and system design are discussed.     

Some aspects of the effect of pH and acid stress in heap bioleaching

The chemical and physical conditions in sulphide heaps provide a complex environment for micro-organisms, with differences in redox potential, acidity, temperature, oxygen and solution chemistry conditions being experienced both temporally and spatially. One of the most important parameters for successful microbial colonisation and active microbial metabolism is suitable pH conditions in the heap. Typically heaps reach tens of metres high and the pH of irrigation solution travelling through heap changes significantly.In this study, we investigated the effect of pH and acid stress for moderately thermophilic and thermophilic mixed cultures, operating at 50-60 °C in a heap bioleaching environment. Results collected from laboratory scale column reactors packed with the low grade whole ore and irrigated with different pH solutions during a temperature shift from moderately thermophilic conditions to thermophilic conditions are discussed.     

The sol-gel technology application of cotton textile processing

In this research, pure cotton textile was modified by the sol-gel technology with low thermal post-treatment temperatures: drying at 90 °C for 10 min after curing at 120, 140 and 160 °C for 2 min. The impact of the cotton textile coating by sol-gel technology, different curing temperatures and multiple washing cycles to the adhesion of the coating, textile air permeability and abrasion resistance were studied. The morphology changes of the cotton textile surface before and after coating, and after multiple washing cycles were evaluated by scanning electron microscopy. The sol-gel treatment can impart antibacterial properties to the textile against Pseudomonas aeruginosa and Staphylococcus epidermidis, by the reduction of the bacteria adhesion with the cotton textile. All test results evince about a very good coating containing Zn and Si adhesion with cotton textile fibres..     

Viability of endolithic micro-organisms in rocks from the McMurdo Dry Valleys of Antarctica established by confocal and fluorescence microscopy

The rocks of the McMurdo Dry Valleys desert in Antarctica harbour endolithic communities of micro‐organisms such as lichens, fungi, cyanobacteria and bacteria. Establishing the physiological status and viability of these microbial colonies in their natural microhabitat has far‐reaching implications for understanding the microbial ecology of the harsh environment of this polar desert. Here we describe the use of confocal microscopy and a specific fluorescent probe (FUN‐1) to evaluate the metabolic activity of fungal cells. Application of confocal microscopy also served to identify living and dead bacteria or cyanobacteria using the fluorescent assay reagents Live/Dead SYTO 9 and propidium iodide or SYTOX Green, respectively. In addition, through the use of epifluorescence microscopy, live/dead bacteria and cyanobacteria could be detected by estimating fluorescence from their cell components provoked by simultaneously staining with nucleic acids stains such as DAPI and SYTOX Green.     

Bioethanol production from tuber crops using fermentation technology: a review

Bioethanol, an alcohol produced by fermentation of plant biomass containing starch and sugars by micro-organisms, considered as a dominant form of fuel for future. Production of this renewable fuel, especially from starchy materials such as tuber crops, holds a remarkable potential to meet the future energy demand because of its high production and comparitively less demand for use as food and fodder. This review focuses on the world bioethanol production scenario from various tuber crops, namely cassava, sweet potato, potato, yam, aroids, sugar beet, etc., fermentation techniques and micro-organisms used in fermentation process along with its future prospects. The advances in metabolic pathway engineering and genetic engineering techniques have led to the development of micro-organisms capable of efficiently converting biomass sugars into ethanol. Several biotechnological tools that are also available for the improvement of microorganisms to meet the harsh environments typically met with certain industrial fermentation process are also discussed.     

软质PVC水管抗菌剂

本文就软质PVC小口径连接水管如何符合英国BS6920-2.4:2000标准中的微生物生长标准展开研究,首先提出和实验证实了,在PVC中添加能永久产生阳离子的矿物填料和有机无机复合抗菌剂,抑制和杀灭PVC软管内水体中的微生物,使之符合英国"与水接触非金属材料产品的安全性评估标准",为使软质PVC连接水管大量进入英国和欧盟各国打开通道。     

几种食品微生物降解黄曲霉毒素作用的研究

通过固体表面培养测定黄曲霉毒素（以下简写为Afl)b1荧光反应降解圈大小和液体摇瓶培养后测定培养其中残余黄曲霉毒素b1（以下简写为Aflb1）含量,研究了食品上常用的几种微生物,乳酸菌、醋酸菌、面包酵母、酿酒酵母、米曲霉和枯草杆菌的Afl的降解能力。这几种微生物中,枯草杆菌、乳酸菌和醋酸菌的Afl降解能力最强,在液体培养60h后,Aflb1可分别被去除89％、88％和81％。枯草杆菌的最适生长温度和pH也是其降解Afl的最适作用pH。培养基中添加钙或镁离子可以促进枯草杆菌对Afl的去除作用。     

稳定同位素技术研究湿地甲烷产生的微生物过程进展

湿地甲烷排放对于全球大气甲烷浓度起着关键作用,深入了解湿地甲烷排放的微生物过程对于构建甲烷排放的过程模型和解决全球甲烷排放清单的不确定性极为重要。本文简要介绍湿地微生物产生甲烷的基本过程,以及利用稳定同位素技术研究甲烷产生的不同途径和不同微生物种类在甲烷产生过程中的作用,并分析该领域的最新研究进展和未来研究重点。利用稳定同位素技术研究湿地环境中各种产甲烷途径贡献的难点在于醋酸产甲烷途径和CO2产甲烷途径的同位素分馏因子的确定。利用稳定同位素技术研究不同微生物种类在甲烷产生过程中的实际功能,明显优于传统的分子生物学方法,这两种技术的结合将为建立微生物的群落结构、功能结构与对应的代谢功能之间的关系提供新的研究思路。     

湿法烟气脱硫技术研究现状及进展

介绍了国内外已工业应用的主要湿法烟气脱硫技术,如石灰石/石灰-石膏湿法、海水烟气脱硫和微生物法等工艺技术的应用现状及研究发展,并对近年来国内外发展的脱硫新工艺进行了评述。由此探讨了湿法烟气脱硫技术现在存在的问题、研究情况和发展前景。     

Removal of soluble organic carbon from winery and distillery wastewaters by application to soil

A logistic model was used to describe the removal of water-soluble carbon from synthetic winery and distillery wastewaters containing ¹⁴C-labelled lactic acid and glycerol after their application to the top-soils of a brown earth and a solod. Decreases in the radioactivity of soil extracts during the first hour after application were ascribed to microbial uptake and adsorption. Oxidative microbial decay was responsible for the removal of the remaining ¹⁴C of the solution to concentrations of less than 5% of the applied ¹⁴C, with removal times dependent on the duration of a lag period (when present) and the rate of decay. Soils from existing wastewater disposal sites containing adapted populations of micro-organisms had shorter lag periods and faster rates of oxidative decay than newly exposed soils. When the loading of organic material was increased, higher concentrations of added ¹⁴C remained in the soil solution after initial microbial uptake or adsorption, and the lag periods were often prolonged. Their combined effects could not be fully offset by concurrent increased rates of oxidative microbial decay, which overall resulted in longer removal times. The disappearance of extractable ¹⁴C to concentrations of less than 5% of input ¹⁴C was used as the basis for determining the minimum times required between successive irrigations with wastewater, which increased in the order of acclimatised solod (0.3–1.4 d) < acclimatised brown earth (0.7–2.6 d) < non-acclimatised brown earth (1.1–4.5 d) < non-acclimatised solod (0.7–4.8 d). Estimates based on the evolution of ¹⁴CO₂were found to be less reliable, due to the continuous turnover of the ¹⁴C of the biomass after the extractable ¹⁴C had disappeared.