Alteration of a cement matrix subjected to biolixiviation test

This paper reports on the assessment of durability and long-term performance of a cement matrix subjected to heterotrophic microbial mediated degradation. In near surface disposal facilities for hazardous and radioactive wastes, microbial activities may likely, in a long-term perspective threaten the integrity of cement-solidified wastes. To investigate the detrimental impact of heterotrophic microorganisms on cement matrices, Aspergillus niger reputed as versatile and prevalent fungus in soil flora was selected as candidate. It was shown that this fungus has the potential of severely degrading ordinary Portland cement pastes through organic acids production. Cement pastes experienced chemical alterations such as substantial leaching of calcium, and mechanical degradation was evident as highlighted by the drastic decline in Young’s modulus. Their poor behaviour with respect to heterotrophic biodeterioration and susceptibility to failure were therefore demonstrated. Consequently, biolixiviation scenario should be seriously considered in order to ensure safe long-term disposal for cement-solidified wastes.

真菌黑色素辐射防护作用综述

从电子转移和能量传递作用、自由基清除作用、金属螯合作用及光保护作用等方面总结了近年来对真菌黑色素辐射防护作用机制的研究进展。在未来研究中,真菌黑色素二级结构的确定,能量传递作用以及在生物体内的辐射防护作用将成为其研究的突破方向。     

酸性土壤适生VA真菌菌种筛选研究

国外利用ＶＡ真菌提高植物抗逆能力、增加复垦区贫瘠土壤培肥速度的研究，是当前现代微生物技术研究领域的新热点。文章在概述了美国磷矿山、煤矿山的应用试验基础上，重点介绍了在我国首次为酸性土壤筛选适生优势ＶＡ真菌菌种的室内研究方法与结果。详细评价了侵染能力强、繁殖能力好的两个优势菌种的五个优势菌株，为我国南方矿山复垦区应用ＶＡ真菌技术提供了依据     

Exposure to aerosolized bacteria and fungi among collectors of commercial, mixed residential, recyclable and compostable waste

Biological hazards associated with the collection of solid and compostable waste have not been well characterized in North America. This is an issue because workers who handle such materials may be exposed to bioaerosols (airborne bacteria and fungi) and dusts resulting in infections or allergic diseases. We conducted a personal sampling campaign for culturable bacteria and fungi in the breathing zones of waste collectors in a variety of typical work settings (scenarios) in the province of Quebec, Canada. Total culturable bacterial and fungal counts were analyzed and compared to ambient environmental levels (background) to determine the degree of incremental exposure among workers. In several scenarios, worker exposure counts were significantly (p < or = 0.05) higher than ambient levels measured upwind, with the highest personal exposures to bacteria observed for urban compostable waste collectors (median = 50,300 Colony Forming Units/m(3) of air (CFU/m(3))). On the other hand, fungal counts collected on an every-other-week cycle were highest among a group of rural compostable waste collectors (median = 101,700 CFU/m(3)). Similar exposures to culturable bacteria and fungi have been reported in European workers who showed such adverse health effects as nausea, diarrhea, upper respiratory tract irritation, and allergy. Therefore, it may be necessary to modify certain work practices in order to minimize exposure. Recommendations include automation of waste and compost collection, use of personal protective equipment including goggles, gloves, and disposable masks, and meticulous personal hygiene.     

Deoxynivalenol and its masked forms: Characteristics,incidence, control and fate during wheat and wheat based products processing - A review

BackgroundDeoxynivalenol (DON) is a toxic secondary metabolite primarily produced by Fusarium graminearum and Fusarium culmorum that is common in grains, such as wheat and wheat-based products.Scope and approachThis review points out on the main DON-producing fungi, the factors affecting DON production, its toxicological aspects and preventive measures to avoid contamination of foods by DON. Further, the article discusses the fate of DON throughout the processing of wheat, bread, and pasta and finally critically assesses data on the impact of specific steps of processing on DON contents in wheat-based products.Key findings and conclusionsThe proposed controls at pre- and post-harvest stages seem to comprise the most efficient strategies to manage the incidence of DON in wheat and wheat-based products. Prevention of plant infection by Fusarium species, managing crops and ensuring the rapid drying of wheat after harvest is the effective approaches for the elimination of DON contamination. There has been contradictory data in the literature on the fate of DON during wheat and wheat-based products processing Due to differences in processing, such as temperature, additives, processing time and loaf size in addition to the occurrence of modified (masked) forms of DON. Therefore, further research must be carried out aiming to reveal the formation and occurrence of modified forms of DON. These compounds can be formed throughout wheat processing, from pre-harvest to processing of wheat-based products, and for proper quantification, analytical methods able to quantify modified forms of DON are required.     

真菌群体感应分子法尼醇及其作用机制

群体感应(quorum sensing,QS)是取决于细胞密度的微生物通信机制,可调节细菌毒力因子分泌、生物膜形成、感受态和生物发光等行为。真菌群体感应系统10年前在法尼醇控制致病多态性真菌白色念珠菌中的细丝化研究中被发现。研究显示法尼醇作为群体感应分子(QSM)对宿主和其他微生物发挥多种作用;还发现芳香醇酪醇是控制白色念珠菌生长、形态发生和生物膜形成的另一群体感应分子。在酿酒酵母中,发现另两种芳香醇苯乙醇和色氨酸是在氮饥饿条件下调节形态发生的群体感应分子。此外,类似于群体感应的种群密度依赖性行为已在几种其他真菌中描述。本综述总结了目前发现群体感应效应的几种关键真菌物种,并重点阐述了研究较多的白色念珠菌和法尼醇作用的微观机制研究进展。     

Assessment of home environments with a fungal index using hydrophilic and xerophilic fungi as biologic sensors

Previously, the author proposed a 'fungal index' that quantifies the capacity for fungal growth in a test environment where a device (fungal detector) encapsulating spores of a xerophilic sensor fungus Eurotium herbariorum was placed. It was also found that an extremely xerophilic fungus, Aspergillus penicillioides, was suitable as a sensor fungus at sites with lower relative humidity (RH). In this report, the hydrophilic fungus Alternaria alternata was added to sensor fungi for the determination of the index in extremely humid environments. Measurements of the index and observations of the formation of spores by the sensor fungi were made in stable climates in moisture chambers, under natural conditions in homes, and in bathrooms prepared in an artificial climate chamber. Higher index values and earlier sporulation were obtained at higher RH in stable climates. The hydrophilic Alt. alternata showed the greatest response at 100% and 97.3% RH, the moderately xerophilic Eur. herbariorum, at 94%, 84%, and 75% RH, and the extremely xerophilic Asp. penicillioides, at 71% RH. In homes, the hydrophilic fungus was most active in water-usage areas, and the xerophilic fungi were most active in non-water-usage areas. Sporulation was observed on sensor fungi in fungal detectors placed in rooms where the index exceeded 18 ru/week after one-month exposure. Sites where the index exceeded 18 ru/week were referred to as damp, where fungal contamination seems to be unavoidable. Evaluations of ventilation systems in bathrooms with extremely humid climates showed typical examples of a countermeasure to fungal contamination. PRACTICAL IMPLICATIONS: The purpose of this study is to establish a fungal index applicable in home environments with extremely high to relatively low relative humidity climates. The sensor fungus that showed the greatest response in a fungal detector (a device encapsulating spores of sensor fungi) served as not only a quantitative but also a qualitative indicator of the environment tested, indicating the type of fungi that would contaminate the site. A fungal index would be a good tool for detecting dampness that induces fungal contamination, which has adverse effects on human health. Evaluations of indoor climates would provide information useful to building owners, builders, designers, advisers, medical practitioners, and so on. Selection of the most suitable insulation systems in various buildings under different climates or evaluations of the drying process in water-damaged buildings could also be possible using fungal detectors and measurements of fungal indices.     

Complex microbiota of a Chinese "Fen" liquor fermentation starter (Fen-Daqu), revealed by culture-dependent and culture-independent methods

Daqu is a traditional fermentation starter that is used for Chinese liquor production. Although partly mechanized, its manufacturing process has remained traditional. We investigated the microbial diversity of Fen-Daqu, a starter for light-flavour liquor, using combined culture-dependent and culture-independent approaches (PCR-DGGE). A total of 190 microbial strains, comprising 109 bacteria and 81 yeasts and moulds, were isolated and identified on the basis of the sequences of their 16S rDNA (bacteria) and 26S rDNA and ITS regions (fungi). DGGE of DNA extracted from Daqu was used to complement the culture-dependent method in order to include non-culturable microbes. Both approaches revealed that Bacillus licheniformis was an abundant bacterial species, and Saccharomycopsis fibuligera, Wickerhamomyces anomalus, and Pichia kudriavzevii were the most common yeasts encountered in Fen-Daqu. Six genera of moulds (Absidia, Aspergillus, Mucor, Rhizopus, Rhizomucor and Penicillium) were found. The potential function of these microorganisms in starters for alcoholic fermentation is discussed. In general the culture-based findings overlapped with those obtained by DGGE by a large extent. However, Weissella cibaria, Weissella confusa, Staphylococcus saprophyticus, Enterobacter aerogenes, Lactobacillus sanfranciscensis, Lactobacillus lactis, and Bacillus megaterium were only revealed by DGGE.     

霉变油炸小食品中鲜绿青霉菌的分离鉴定研究

食品安全问题是关系人体健康和国计民生的重大问题,已经引起人们的高度重视。利用稀释涂布法从霉变油炸小食品中分离获得1株菌,形态学观察初步鉴定为酵母菌。通过单因素试验及L9(34)正交试验对菌种的生长条件进行研究,确定最适培养温度38℃、培养时间75 h、摇床转速200 r/min、碳氮比5∶1。在真菌DNA提取过程中尝试了SDS法和CTAB法。除蛋白采取了酚/氯仿的方法 ,对所得样品进行DNA凝胶电泳、质量检测和PCR扩增产物。用18SrDNA ITS的直接测序法测序后构建系统发育树确定:该菌为鲜绿青霉菌(Penicillium viridicatum)。     

New type of pressurized cultivation method providing oxygen for piezotolerant yeast

For efficient oxygen supply to pressurized culture, we developed a method using a highly pressurized membrane reactor with an air-saturated medium circulation system. The new method increased the cell growth of aerobic yeast approximately 20 folds larger than that in the case of using a conventional method.