The Incidence of Fungi and Mycotoxins in South Africa Wheat and Wheat-Based Products

This investigation was undertaken to survey the fungal and mycotoxin contamination of South African wheat ranging from that growing in the field to processed wheat products. Samples of wheat were taken from various growing areas in South Africa and screened for fungi and mycotoxins, using a range of methodologies, including chromatography, immunoaffinity/fluorimetry, and cytotoxicity testing. Similar samples were taken from supermarkets and retail outlets in South Africa and analyzed in a similar manner. The result showed that a range of fungi and mycotoxins could be detected in wheat in all these sample types. The major fungal contaminants were Fusarium spp. and their attendant mycotoxins, in particular deoxynivalenol, which is in keeping with the observations made in the rest of the world. An interesting observation was that samples of wheat taken from the field with heavy Fusarium contamination were contaminated with fumonisin B₁, which is not normally associated with this crop. Of more concern were the low but persistent levels of mycotoxins and fungi in wheat-based products sold directly to the public.     

The incidence of fungi and mycotoxins in South African barley and barley products

Barley is grown as a crop in South Africa, mainly for use in the barley beer (lager) industry, particularly in the production of barley malt. This investigation was done to find out what fungal infection and mycotoxin contamination this barley and the malt contained. The survey, done in 2005, not only covered barley and malt but also the final product in the form of several brands of beer purchased from retail outlets. Analysis was done using a range of methodologies including chromatography, immunoaffinity/fluorimetry and cytotoxicity testing. The results show that barley, which also includes barley sold directly to the public, and malt, contain various fungi, sometimes at high incidence and also a range of mycotoxins which persisted through, although at low levels, to beer. The malt showed a different pattern of micro flora, as compared to the barley, which indicates infection during the malting process, which is not uncommon. Interestingly, fumonisin B1 was found in some of the samples, as well as the beer, although in the latter case these were at very low levels. Recent studies have shown that the immunoaffinity/fluorimetry method can give false positives for the fumonisins, so these results were confirmed by high performance liquid chromatography. As is the case with other cereals grown in South Africa, there is the concern that the public is exposed to mycotoxins on a regular basis through the consumption of products made from them.     

Occurrence of mycotoxins in wheat grains exposed to fungicides on fusarium head blight control in southern Brazil

Mycotoxins occurrence in wheat grains impose risks to human and animal health. The southern Brazil has favorable weather conditions for Fusarium graminearum infections and consequently for mycotoxins accumulation on grains. The goal of this study was to evaluate the behavior of new wheat commercial genotypes to Fusarium Head Blight (FHB), to control performance of new fungicide formulations and their relationship with mycotoxins concentration in grains. The manly mycotoxin occurrence on wheat grains in southern Brazil was deoxynivalenol (DON). Two cultivars showed high DON concentration above the tolerance limits (>3000 μg kg^?1). Many other mycotoxins monitored presented concentrations below method detection limit. Satisfactory levels of fungicide effectiveness were achieved against F. graminearum. Some fungicides promoted a satisfactory decrease on DON accumulation in grains. The best results were obtained when prothioconazole was present. SDHI (Succinate dehydrogenase inhibitors) + QoI (Quinone outside inhibitors) fungicides showed benefic effects at FHB control at field, but it did not promote satisfactory reduction on DON contamination. Fungicides can be used satisfactory for FHB control and reduce DON contamination in grains in southern Brazil. The presence of prothioconazole should be recommended. Some genotypes showed high DON concentration and it was not directly related with FHB severity at field.     

Environment contamination by mycotoxins and their occurrence in food and feed: Physiological aspects and economical approach

The contamination of food and feed by mycotoxins as toxic metabolites of fungi is a risk not only for consumers resulting in various embarrassment regarding health status and well-being, but also for producers, companies and export market on the ground of economic losses and ruined stability of economic trade. As it is given in historical evidence, the contamination of food by mycotoxins is a topic as old as a history of mankind, finding some evidence even in the ancient books and records. Nowadays, the mycotoxins are used in modern biotechnological laboratories and are considered an agent for targeting the specific cells (e.g., defected cells to eliminate them). However, this promising procedure is only the beginning. More concern is focused on mycotoxins as abiotic hazard agents. The dealing with them, systematic monitoring, and development of techniques for their elimination from agricultural commodities are worldwide issues concerning all countries. They can be found alone or in co-occurrence with other mycotoxins. Thus, this review aims to provide widened information regarding mycotoxins contamination in environment with the consequences on health of animals and humans. The inevitability for more data that correctly determine the risk points linked to mycotoxins occurrence and their specific reactions in the environment is demonstrated. This review includes various symptoms in animals and humans that result from mycotoxin exposure. For better understanding of mycotoxin's impact on animals, the sensitivities of various animal species to various mycotoxins are listed. Strategies for elimination and preventing the risks of mycotoxins contamination as well as economical approach are discussed. To complete the topic, some data from past as historical evidences are presented.     

自由表面流人工湿地微生物气溶胶研究

微生物气溶胶的种类、浓度和粒径分布与人类健康关系密切。采用MD8空气浮游菌采样仪和FA-1型6级筛孔撞击式空气微生物采样器,对人工湿地细菌和真菌气溶胶的数量和粒径分布进行研究。结果表明,人工湿地进水前,细菌和真菌气溶胶平均值较低,分别为64.0、126.0CFU/m3;进水后,细菌气溶胶平均值在6月26日达到最高,为2292.5CFU/m3,真菌气溶胶平均值在8月27日达到最高,为6200.0CFU/m3;易进入肺部的细菌和真菌(粒径为0.65～4.70μm)粒子数分别占粒子总数的22.2%～62.3%、54.2%～87.6%;空气细菌中值直径为1.88～4.13μm,空气真菌中值直径在3.00μm左右波动。空气细菌中革兰氏阳性菌明显多于革兰氏阴性菌,空气真菌主要为酵母菌、镰刀菌属、枝孢属、毛霉属、交链孢属、肉座菌属、枝霉属、青霉属和曲霉属。     

Spatial distribution of atmospheric PAHs and PCNs along a north-south Atlantic transect

Ship-board air samples collected between The Netherlands and South Africa in January-February 2001 were analysed for polycyclic aromatic hydrocarbons (PAHs) and polychlorinated naphthalenes (PCNs). The highest PAH concentrations occurred in the European samples, and in samples close to West Africa and South Africa. Consistently low PAH concentrations were measured in the southern hemisphere open ocean samples (190-680 pg/m3). The highest PCN concentrations occurred in the European samples, but high values were also detected off the West African coast, and in the sample taken closest to South Africa. Data are presented for diurnal cycles taken in the remote South Atlantic. The day:night ratios of phenanthrene, 1-methylphenanthrene and fluoranthene were typically approximately 1.5-2.5:1. The mechanism(s) causing this observation is/are not understood at present, but dynamic environmental process(es) is/are implicated.     

Survey of selected mycotoxins in food

The contamination of a variety of foods with the mycotoxins aflatoxins B1, B2, G1, M1, ochratoxin A, patulin, and byssochlamic acid was investigated. With the developed methods, the identification was made possible by in situ fluorescence spectral analysis with a far reaching exclusion of substances which simulate sycotoxins. Aflatoxin B1 was detected in 2 samples of 105 spontaneously moulded food specimens and only in 1 of a group of 198 food samples that were obviously not moulded. Aflatoxin M1 was identified in 4 of 60 samples of the so-called wintermilk. Investigated dairy products did not contain aflatoxin M1. Ochratoxin A could be detected twice in 49 spontaneously moulded corn samples, aflatoxin, however, was not found. Further investigations of 50 samples of moulded food revealed ochratoxin A in 2 samples of raw coffee. Food samples obviously not moulded did not contain ochratoxin A. Patulin was detected in 19 of 110 samples of fruit and fruit products, especially in commercial apple juice, in rotten parts of apples, and in moulded fruit products. Byssochlamic acid was not detected in fruit juices or in fruit. The toxicological consequences of mycotoxins in food and possibilities to reduce mycotoxins are discussed.     

Mycotoxins of Aspergillus fumigatus in pure culture and in native bioaerosols from compost facilities

Exposure to secondary metabolites of airborne fungi in waste handling facilities is discussed in regard to potential toxic impacts on human health. The relevance of mycotoxins has been intensely studied in connection with contamination of food and feed. Toxic secondary metabolites are expected to be present in airborne spores, but exposure to mycotoxins in bioaerosols has not been studied sufficiently. Aspergillus fumigatus is one of the most frequent species in the air of compost plants. A wide range of secondary metabolites was found in pure cultures of freshly isolated strains of A. fumigatus. Tryptoquivaline, a compound with tremorgenic properties, and trypacidin, for which no toxic properties are described, were found in native bioaerosols in a compost facility. The highly toxic metabolites gliotoxin and verruculogen were not found in the bioaerosols.     

Crude oil and hydrocarbon-degrading strains of Rhodococcus rhodochrous isolated from soil and marine environments in Kuwait

Soil and marine samples collected from different localities in Kuwait were screened for microorganisms capable of oil degradation. Both fungi and bacteria were isolated. The fungal flora consisted of Aspergillus terreus, A. sulphureus, Mucor globosus, Fusarium sp. and Penicillum citrinum. Mucor globosus was the most active oil degrading fungus isolated. Bacterial isolates included Bacillus spp. Enterobacteriaceae, Pseudomonas spp., Nocardia spp., Streptomyces spp.,and Rhodococcus spp. Among these Rhodococcus strains were the most efficient in oil degradation and, relatively speaking, the most abundant. Bacterial and fungal isolates differed in their ability to degrade crude oil, with Rhodococcus isolates being more active that fungin in n-alkane biodegradation, particularly in the case of R. rhodochrous. In addition to medium chain n-alkanes, fungi utilized one or more of the aromatic hydrocarbons studied, while bacteria failed to do so. R. rhodochorous KUCC 8801 was shown by GLC and post-growth studies to be more efficient in oil degradation than isolates known to be active oil degraders.     

Effect of gaseous chlorine dioxide on indoor microbial contaminants

Traditional and modern techniques for bioaerosol enumeration were used to evaluate the relative efficiency of gaseous chlorine dioxide (ClO2) in reducing the indoor microbial contamination under field and laboratory conditions. The field study was performed in a highly microbially contaminated house, which had had an undetected roof leak for an extended period of time and exhibited large areas of visible microbial growth. Air concentrations of culturable fungi and bacteria, total fungi determined by microscopic count and polymerase chain reaction (PCR) assays, endotoxin, and (1 --> 3)-beta-D-glucan were determined before and after the house was tented and treated with ClO2. The laboratory study was designed to evaluate the efficiency of ClO2 treatment against known concentrations of spores of Aspergillus versicolor and Stachybotrys chartarum on filter paper (surrogate for surface treatment). These species are commonly found in damp indoor environments and were detected in the field study. Upon analysis of the environmental data from the treated house, it was found that the culturable bacteria and fungi as well as total count of fungi (as determined by microscopic count and PCR) were decreased at least 85% after the ClO2 application. However, microscopic analyses of tape samples collected from surfaces after treatment showed that the fungal structures were still present on surfaces. There was no statistically significant change in airborne endotoxin and (1 --> 3)-beta-D-glucan concentration in the field study. The laboratory study supported these results and showed a nonsignificant increase in the concentration of (1 --> 3)-beta-D-glucan after ClO2 treatment.     

Mycobiota and mycotoxins in bee pollen collected from different areas of Slovakia

Contamination by microscopic fungi and mycotoxins in different bee pollen samples, which were stored under three different ways of storing as freezing, drying and UV radiation, was investigated. During spring 2009, 45 samples of bee-collected pollen were gathered from beekeepers who placed their bee colonies on monocultures of sunflower, rape and poppy fields within their flying distance. Bee pollen was collected from bees' legs by special devices placed at the entrance to hives. Samples were examined for the concentration and identification of microscopic fungi able to grow on Malt and Czapek-Dox agar and mycotoxins content [deoxynivalenol (DON), T-2 toxin (T-2), zearalenone (ZON) and total aflatoxins (AFL), fumonisins (FUM), ochratoxins (OTA)] by direct competitive enzyme-linked immunosorbent assays (ELISA). The total number of microscopic fungi in this study ranged from 2.98 ± 0.02 in frozen sunflower bee pollen to 4.06 ± 0.10 log cfu.g(-1) in sunflower bee pollen after UV radiation. In this study, 449 isolates belonging to 21 fungal species representing 9 genera were found in 45 samples of bee pollen. The total isolates were detected in frozen poppy pollen 29, rape pollen 40, sunflower pollen 80, in dried poppy pollen 12, rape pollen 36, sunflower 78, in poppy pollen after UV radiation treatment 54, rape 59 and sunflower 58. The most frequent isolates of microscopic fungi found in bee pollen samples of all prevalent species were Mucor mucedo (49 isolates), Alternaria alternata (40 isolates), Mucor hiemalis (40 isolates), Aspergillus fumigatus (33 isolates) and Cladosporium cladosporioides (31 isolates). The most frequently found isolates were detected in sunflower bee pollen frozen (80 isolates) and the lowest number of isolates was observed in poppy bee pollen dried (12 isolates). The most prevalent mycotoxin of poppy bee pollen was ZON (361.55 ± 0.26 μg.kg(-1)), in rape bee pollen T-2 toxin (265.40 ± 0.18 μg.kg(-1)) and in sunflower bee pollen T-2 toxin (364.72 ± 0.13 μg.kg(-1)) in all cases in frozen samples.     

Potential of hexadecane-utilizing soil-microorganisms for growth on hexadecanol, hexadecanal and hexadecanoic acid as sole sources of carbon and energy

Bacteria and fungi in pristine and oily desert soil samples were counted on inorganic medium aliquots containing 0.5% hexadecane, hexadecanol, hexadecanal or hexadecanoic acid, as sole sources of carbon and energy. It was found that the carbon and energy source most commonly utilized by soil bacteria was the alkane n-hexadecane, and by soil fungi hexadecanoic acid. Representative microorganisms were isolated and identified. The most predominant bacteria in all soil samples belonged to the genera Micrococcus and Pseudomonas; less dominant bacteria belonged to the group of nocardioforms. The most frequent fungal genera were Aspergillus and Penicillium, while Microsporium and Ulocladium were minor fungi. Irrespective of the substrate on which the microbial strains had initially been isolated, the majority of the isolated microorganisms could grow, albeit to a varying degree, on an inorganic medium containing any of the remaining three substrates as sole carbon and energy sources. Bacterial strains preferred the alkane as a carbon and energy source over any of its oxidation products, while fungal strains preferred to grow mainly on the fatty acids. Quantitative analysis by gas liquid chromatography revealed that the predominant bacterial and fungal isolates had a potential for the attenuation of the alkane and its immediate oxidation products in the medium. In view of the continuous release of hydrocarbon oxidation products by oil-utilizing microorganisms in oily environments, it is interesting that the indigenous microflora contribute to the uptake and utilization of all such intermediate compounds, thus, having a potential for efficient self-cleaning and bioremediation of oily soils.     

Exposure estimates to Fusarium mycotoxins through cereals intake

Mycotoxins are harmful substances produced by fungi in several commodities with a widespread presence in foodstuffs. Human exposure to mycotoxins occurs mainly by contaminated food. The quantitation of mycotoxins in cereal-based food, highly consumed by different age population, is of concern. In this survey, 159 cereal-based samples classified as wheat, maize and rice-based, have been evaluated for the occurrence of patulin, deoxynivalenol, 3-acetyl-deoxynivalenol, fusarenon-X, diacetoxyscirpenol, nivalenol, neosolaniol, HT-2, T-2 and zearalenone by gas chromatography–tandem mass spectrometry. Intakes were calculated for average consumers among adults, children and infants and compared with the tolerable daily intakes (TDI). Data obtained were used to estimate the potential exposure levels. 65.4% of the samples were contaminated with at least one mycotoxin and 15.7% of the analyzed samples showed co-occurrence of mycotoxin. The dietary exposure to HT-2 and T-2 toxins was estimated as 0.010 and 0.086 μg kg⁻¹ bw d⁻¹, amounting to 10% and 86% of the TDI, for adults and infants respectively. These results back up the necessity to take a vigilant attitude in order to minimize human intake of mycotoxins.     

Culturability and concentration of indoor and outdoor airborne fungi in six single-family homes

In this study, the culturability of indoor and outdoor airborne fungi was determined through long-term sampling (24-h) using a Button Personal Inhalable Aerosol Sampler. The air samples were collected during three seasons in six Cincinnati area homes that were free from moisture damage or visible mold. Cultivation and total microscopic enumeration methods were employed for the sample analysis. The geometric means of indoor and outdoor culturable fungal concentrations were 88 and 102 colony-forming units (CFU) m(-3), respectively, with a geometric mean of the I/O ratio equal to 0.66. Overall, 26 genera of culturable fungi were recovered from the indoor and outdoor samples. For total fungal spores, the indoor and outdoor geometric means were 211 and 605 spores m(-3), respectively, with a geometric mean of I/O ratio equal to 0.32. The identification revealed 37 fungal genera from indoor and outdoor samples based on the total spore analysis. Indoor and outdoor concentrations of culturable and total fungal spores showed significant correlations (r = 0.655, p<0.0001 and r = 0.633, p<0.0001, respectively). The indoor and outdoor median viabilities of fungi were 55% and 25%, respectively, which indicates that indoor environment provides more favorable survival conditions for the aerosolized fungi. Among the seasons, the highest indoor and outdoor culturability of fungi was observed in the fall. Cladosporium had a highest median value of culturability (38% and 33% for indoor and outdoor, respectively) followed by Aspergillus/Penicillium (9% and 2%) among predominant genera of fungi. Increased culturability of fungi inside the homes may have important implications because of the potential increase in the release of allergens from viable spores and pathogenicity of viable fungi on immunocompromised individuals.     

Biodegradation of chlorpyrifos by either single or combined cultures of some soilborne plant pathogenic fungi

Abstract

Biodegradation of chlorpyrifos was studied in liquid culture media amended with either single or combined eight different plant pathogenic fungi isolated from the continuous cropping wheat fields. The average recovery of chlorpyrifos from the liquid media was found to be 86.1%. The detection limit of chlorpyrifos by the analytical method used was 19 ppb. Data showed that the growth of mixed fungi at concentrations up to 200 ppm of chlorpyrifos was higher than in the control treatment. Chlorpyrifos concentrations declined in the medium of combined fungi more than it did in the medium of any single fungus with increase in the incubation period. The amount of chlorpyrifos recovered was 79.8 ppm (39.9%) in the combined fungal cultures after 21 days. However, those recovered from the media of Fusarium graminearum, F. oxysporum, Rhizoctonia solani, Cladosporhim cladosporiodes, Cephalosporium sp., Trichoderma viridi, Alternaria alternata, and Cladorrhinum brunnescens, ranged from 48.0 to 74.8%. The half‐life value (T_1/2) for chlorpynfos was 15.8 day in the medium amended with mixed fungi. However, for the single cultures it ranged from 19.3 to 33.0 day.     

氯氰菊酯降解真菌的筛选及其降解特性研究

用富集培养的方法从农药厂污水排放口的污泥中分离筛选到3株以氯氰菊酯为唯一碳源进行生长的真菌,分别命名为TS-203、TS-205和TS-306。经鉴定3株真菌分别属于土生曲霉组(Aspergillus terreus)、毛链孢属(M onilochaetes)和镰孢霉属(Fusarium)。分别测定了不同碳源、pH、培养温度及氯氰菊酯浓度对真菌生长量和降解能力的影响。结果表明,以氯氰菊酯为唯一碳源且浓度为50~150 mg/L,pH 6.0~8.0,培养温度30~40℃时,真菌的生长量较大,降解效果较好。本研究对氯氰菊酯农药残留的生物修复研究和应用具有十分重要的意义,可为今后治理氯氰菊酯残留污染提供参考。     

Mycobiota and mycotoxins in bee pollen collected from different areas of Slovakia

Contamination by microscopic fungi and mycotoxins in different bee pollen samples, which were stored under three different ways of storing as freezing, drying and UV radiation, was investigated. During spring 2009, 45 samples of bee-collected pollen were gathered from beekeepers who placed their bee colonies on monocultures of sunflower, rape and poppy fields within their flying distance. Bee pollen was collected from bees’ legs by special devices placed at the entrance to hives. Samples were examined for the concentration and identification of microscopic fungi able to grow on Malt and Czapek-Dox agar and mycotoxins content [deoxynivalenol (DON), T-2 toxin (T-2), zearalenone (ZON) and total aflatoxins (AFL), fumonisins (FUM), ochratoxins (OTA)] by direct competitive enzyme-linked immunosorbent assays (ELISA). The total number of microscopic fungi in this study ranged from 2.98 ± 0.02 in frozen sunflower bee pollen to 4.06 ± 0.10 log cfu.g^?1 in sunflower bee pollen after UV radiation. In this study, 449 isolates belonging to 21 fungal species representing 9 genera were found in 45 samples of bee pollen. The total isolates were detected in frozen poppy pollen 29, rape pollen 40, sunflower pollen 80, in dried poppy pollen 12, rape pollen 36, sunflower 78, in poppy pollen after UV radiation treatment 54, rape 59 and sunflower 58. The most frequent isolates of microscopic fungi found in bee pollen samples of all prevalent species were Mucor mucedo (49 isolates), Alternaria alternata (40 isolates), Mucor hiemalis (40 isolates), Aspergillus fumigatus (33 isolates) and Cladosporium cladosporioides (31 isolates). The most frequently found isolates were detected in sunflower bee pollen frozen (80 isolates) and the lowest number of isolates was observed in poppy bee pollen dried (12 isolates). The most prevalent mycotoxin of poppy bee pollen was ZON (361.55 ± 0.26 μg.kg^?1), in rape bee pollen T-2 toxin (265.40 ± 0.18 μg.kg^?1) and in sunflower bee pollen T-2 toxin (364.72 ± 0.13 μg.kg^?1) in all cases in frozen samples.     

Investigation of the potential antimicrobial efficacy of sealants used in HVAC systems

Recent experiments confirm field experience that duct cleaning alone may not provide adequate protection from regrowth of fungal contamination on fiberglass duct liner (FGDL). Current recommendations for remediation of fungally contaminated fiberglass duct materials specify complete removal of the materials. But removal of contaminated materials can be extremely expensive. Therefore, a common practice in the duct-cleaning industry is the postcleaning use of antimicrobial surface coatings with the implication that they may contain or limit regrowth. Little information is available on the efficacy of these treatments. This paper describes a study to evaluate whether three commercially available antimicrobial coatings, placed on a cleaned surface that 1 year previously had been actively growing microorganisms, would be able to prevent regrowth. The three coatings contained different active antimicrobial compounds. All three of the coatings were designed for use on heating, ventilation, and air conditioning (HVAC) system components or interior surfaces of lined and unlined duct systems. Coating I was a polyacrylate copolymer containing zinc oxide and borates. Coating II was an acrylic coating containing decabromodiphenyl oxide and antimony trioxide. Coating III was an acrylic primer containing a phosphated quaternary amine complex. The study included field and laboratory assessments. The three treatments were evaluated in an uncontrolled field setting in an actual duct system. The laboratory study broadened the field study to include a range of humidities under controlled conditions. Both static and dynamic chamber laboratory experiments were performed. The results showed that two of the three antimicrobial coatings limited the regrowth of fungal contamination, at least in the short term (the 3-month time span of the study); the third did not. Before use in the field, testing of the efficacy of antimicrobial coatings under realistic use conditions is recommended because antimicrobials have different baseline activities and interact differently with the substrate that contains them and their local environment.     

Hydrolytic and ligninolytic enzyme activities in the Pb contaminated soil inoculated with litter-decomposing fungi

The impact of Pb contamination was tested to five hydrolytic (beta-glucosidase, beta-xylosidase, beta-cellobiosidase, alpha-glucosidase and sulphatase) and two ligninolytic (manganese peroxidase, MnP and laccase) enzyme activities in the humus layer in the forest soil. The ability of eight selected litter-degrading fungi to grow and produce extracellular enzymes in the heavily Pb (40 g Pb of kg ww soil(-1)) contaminated and non-contaminated soil in the non-sterile conditions was also studied. The Pb content in the test soil was close to that of the shooting range at H?lv?l? (37 g Pb of kg ww soil(-1)) in Southern Finland. The fungi were Agaricus bisporus, Agrocybe praecox, Gymnopus peronatus, Gymnopilus sapineus, Mycena galericulata, Gymnopilus luteofolius, Stropharia aeruginosa and Stropharia rugosoannulata. The Pb contamination (40 g Pb of kg ww soil(-1)) was deleterious to all five studied hydrolytic enzyme activities after five weeks of incubation. All five hydrolytic enzyme activities were significantly higher in the soil than in the extract of the soil indicating that a considerable part of enzymes were particle bound in the soils. Hydrolytic enzyme activities were higher in the non-contaminated soil than in the Pb contaminated soil. Fungal inocula increased the hydrolytic enzyme activities beta-cellobiosidase and beta-glucosidase in non-contaminated soils. All five hydrolytic enzyme activities were similar with fungi and without fungi in the Pb contaminated soil. This was in line that Pb contamination (40 g Pb of kg ww soil(-1)) depressed the growth of all fungi compared to those grown without Pb in the soil. Laccase and MnP activities were low in both Pb contaminated and non-contaminated soil cultures. MnP activities were higher in soil cultures containing Pb than without Pb. Our results showed that Pb in the shooting ranges decreased fungal growth and microbial functioning in the soil.     

Loss of particulate contaminants from plant canopies under wet and dry conditions

There is a requirement for data describing the loss with time of particulate contamination from plant canopies. Measurements were made of the loss rates of monodispersed silica spheres (three sizes, with Mass Median Aerodynamic Diameters (MMADs) 1.9, 5.3 and 8.4 microm) from wheat (Triticum aestivum) and broad bean (Vicia faba) canopies. The spheres were labelled with tracers detectable by Instrumental Neutron Activation Analysis (INAA). Canopies were contaminated under realistic turbulence conditions in a wind tunnel, then removed to sheltered and exposed field sites or to a glasshouse containing a rain simulator. Samples were taken periodically, and the level of contamination per plant determined by INAA. Statistical analysis of the resulting data suggested an offset exponential loss model, with a residue of deposit that is not lost over time. Loss half-lives in the order of 1-2 days were obtained for an exposed wheat crop and 3-4 days for a partially sheltered wheat crop, with permanent residues of initial deposit for the exposed crop of 4-8%, and for the partially sheltered crop of 22-52%. A broad bean crop under glasshouse conditions showed loss half-lives of 0.5-1.5 days with residues of 22-26% initial contamination. A double exponential loss model also fitted the data well in some cases, and it is possible that a slow loss of the residual deposit occurs, being masked by noise in the current data set.