浅谈全面深入开展大气微生物污染监测的必要性

由于传染病控制非常迫切,全面深入地开展大气微生物监测就显得非常重要。介绍了大气微生物污染的特点及监测研究现状,给出了大气微生物污染监测实施的方法及措施。     

Determining the effect of acid stress on the persistence and growth of thermophilic microbial species after mesophilic colonisation of low grade ore in a heap leach environment

The microorganisms involved in the bioleaching of sulphidic mineral ores are acidophilic. Generally, a pH in the range of pH 1–2.5 is applied for optimal growth in these systems. In operating heaps, perturbation of conditions could result in changes in the pH outside this “safe” window, so an understanding of the effect of changes in pH on growth and activity of bioleaching microbes is needed. Previous work has shown that some microorganisms e.g. Acidithiobacillus thiooxidans, Leptospirillum ferriphilum and Leptospirillum ferrooxidans are able to adapt to low pH environments (∼pH 0.9). However, most studies on the response of micro-organisms implicated in mineral bioleaching to pH have been conducted under submerged, aerated culture conditions, with limited performance-based studies conducted under conditions mimicking a heap environment. In this study, the effect of acid stress on the persistence of the thermophilic micro-organisms in the ore bed inoculated at mesophilic conditions and their subsequent growth on reaching thermophilic conditions is considered.Following inoculation, five columns loaded with a low grade chalcopyrite ore were irrigated at a feed pH of 1.7 at 25 °C. After a few days, the temperature was sequentially increased from 25 °C through 37 °C to 50 °C, resulting in an Eh above 850 mV across all columns. The irrigation feed pH was then varied across the range pH 1.0 to 1.7 at 50 °C. Eh values greater than 800 mV could be attained in the columns with feed pH values between pH 1.2 and pH 1.7 at 50 °C. The Eh of the column receiving feed solution at a pH of 1.0 at 50 °C dropped to below 700 mV and did not recover. The temperature was then increased gradually to 60 °C. All the columns with feed pH of 1.2 and higher achieved Eh values above 800 mV. Quantitative analyses of the microbial community on selected PLS and ore samples indicated that lower pH affected the persistence of the thermophilic micro-organisms in the ore bed and their subsequent growth on reaching thermophilic conditions. The microbial population detached from the ore sample after 120 days decreased by a factor of 5–15 and 25–100 fold on decreasing the operating pH from 1.5–1.7 to 1.4 and 1.2 respectively. Poor microbial activity was found at pH 1.0, suggesting ineffective growth or persistence of the archaea.     

Microbial contamination of cutting fluids and associated hazards

In this paper, an experimental investigation into the microbial contamination of cutting fluids is presented. The paper confirms the laboratory based results of the fluid biocontamination by culture and identification of the micro-organisms, and their ability to survive in the workshop fluid systems. Direct and/or indirect associations of the identified micro-organisms with the potential health hazards are pointed out.     

活性污泥法中的生物作用

活性污泥是由细菌、微型动物为主的微生物与悬浮物质、胶体物质混杂在一起所形成的絮凝体,通过微生物所产生的酶,氧化分解有机物,从而使水得到净化。在实际应用时要发挥其积极有利的作用,控制活性污泥膨胀,使微生物在污水处理中发挥更好的作用。     

新型天然生物功能食品添加剂的研究与发展

按照用途将现在已研究成熟的新型生物功能食品添加剂大致分为四类:防腐剂、抗氧化剂、增色剂、调味剂。详细介绍新型生物功能添加剂的特点、用途、功效等研究内容及其发展方向。