Fungal and aflatoxin contamination of medicinal herbs

Since the consumption of aromatic and medicinal herbs has been increasing in the last years, the Argentinian Health Authorities are concerned to control the quality and security of them. Fungal and aflatoxin contamination are two parameters to be taken into account, to ensure the harmlessness of the phytomedicinal products. In 81 different samples, grouped in end products (EP), raw material (RM) and at harvest (SH), fungal flora (enumeration and identification) as well as naturalAspergillus flavus and aflatoxin occurrence were investigated. In all samples fungal counts fulfilled the international general recommendation limits (maximum 10⁵ cfu/g). Predominant flora was made up by xerophilic species ofAspergillus(100%), byPeniciIlium (< 50%) and in less percentage byFusarium (5.6%). Among the Aspergilli, A.flavus was present in all the three groups of samples. Using a TLC method, 47% of A. flavus isolates were toxinogenic, producing aflatoxin B₁ and B₂. In herbs, 4.7% of RM samples were naturally contaminated with aflatoxins B₁ and B₂. Considering the carcinogenic activity of aflatoxins it is essential to regulate them in the raw material (vegetal drug).     

Effect of delayed harvest on contamination of pearl millet grain with mycotoxin-producing fungi and mycotoxins

The response to delayed harvest of fungal and mycotoxin contamination of grain of the pearl millet hybrid HGM 100 was examined in 1992 and 1993. Samples of grain were assayed from seven plantings at locations near Tifton, Georgia, USA. Grain was harvested at 30, 40, and 50 days after anthesis and evaluated for infection byFusarium species andAspergillus flavus, and mycotoxin contamination. Mean isolation frequencies ofF. semitectum (35.6%) andF. chlamydosporum (17.2%) increased linearly with delayed harvest.Fusarium moniliforme andF. equisiti were infrequently isolated (<0.5%) and did not increase in the grain when harvest was delayed. Low mean concentrations of zearalenone (0.17 ppm), nivalenol (0.42 ppm), and deoxynivalenol (0.01 ppm) were detected but were not affected by delayed harvest. Isolation frequencies ofF. chlamydosporum andF. equiseti were correlated (P=0.07) with levels of nivalenol.Aspergillus flavus was not isolated from the grain, and aflatoxin concentrations averaged 1.9 ppb.     

Fungal contamination of some imported spices

Seventeen imported raw spice samples obtained from retail outlets were examined for spoilage mould profile. A total of 665 fungal isolates, representing 14 species, were recovered and identified from dried and ground spice samples on several media using standard dilution plate method. Moisture content varied greatly among various samples and were generally high. The most heavily contaminated spice samples examined were observed in red chili and black pepper in order of magnitude of 1580 and 1120 cfu/g, respectively. The most predominant fungal genera encountered were Aspergillus, Penicillium, Rhizopus, Cladosporium and Trichoderma. Yeasts were also frequently recovered, but not identified. Relative occurrence values of taxa disclosed ranged between 36.4% for A. flavus and 0.6% for A. parasiticus and Absidia corymbifera. Samples obtained from gunny bags encounter higher colony counts and contamination frequency than other packing methods. The present magnitude of contamination and spectra of mycobiota approximate those reported for similar spice samples. Although several potentially mycotoxigenic fungi were isolated during the present study, neither the foodstuff nor the fungi were assayed for the presence of these toxins.     

Contamination of common spices in Saudi Arabia markets with potential mycotoxin-producing fungi

Fifteen spices obtained from common markets were examined for their mould profile. A total of 520 fungal isolates, representing 57 species, were recovered and identified from dried and ground spice samples on three different media using standard dilution plate method. The most heavily contaminated spice samples examined were observed in ginger in order of magnitude of 5325–6800 cfu/g. The most predominant fungal genera encountered were Aspergillus, Penicillium, and Rhizopus. Relative occurrence values of taxa disclosed ranged between 80% for Aspergillusflavus, Aspergillusniger and Penicilliumarenicola, and 10% for some species. Samples obtained from sumac encountered very rare colony counts indicating its antifungal prosperities. The present magnitude of contamination and spectra of mycobiota approximate those reported for similar spice samples. Several potentially mycotoxigenic fungi were isolated from the majority of samples. The present study attracts the attention to potential risk for mycotoxins contamination may be caused as a result of using these spices, especially in great quantities. The study strongly recommends reduction in application of heavily contaminated spices like ginger in food processing and using some others like clove and sumac due to their antimicrobial properties.     

Fungal contamination and mycotoxin detection of powdered herbal drugs

Forty-nine powdered herbal drugs were analyzed for their mold profile and for the potential presence of three mycotoxins (aflatoxin, sterigmatocystin, ochratoxin A). Aspergillus and Penicillium species were predominant, but Rhizopus, Mucor, Cladosporium, and Aureobasidium spp. were also found in a few samples. Mycotoxins were not detected in any samples, and only one isolated culture was found to be a mycotoxin producer on laboratory media.     

Fungal contamination and mycotoxin detection of powdered herbal drugs.

Forty-nine powdered herbal drugs were analyzed for their mold profile and for the potential presence of three mycotoxins (aflatoxin, sterigmatocystin, ochratoxin A). Aspergillus and Penicillium species were predominant, but Rhizopus, Mucor, Cladosporium, and Aureobasidium spp. were also found in a few samples. Mycotoxins were not detected in any samples, and only one isolated culture was found to be a mycotoxin producer on laboratory media.     

Fungal contamination and selected mycotoxins in pre- and post-harvest maize in Honduras

Sixty nine samples of maize were collected from pre-harvest standing crops and on-farm storage facilities from 52 smallholder farms located within 4 regions of Honduras during October 1992 and November 1993. Samples were visually assessed for insect damage and fungal spoilage, and the mycoflora quantified on artificial media. The major components of the ear rot complex were:Fusarium moniliforme, F. moniliforme var.subglutinans, Penicillium species,Stenocarpella maydis, S. macrospora andAcremonium spp. Representative samples were also assayed for mycotoxin content. Fumonisin B₁ was detected in all 24 samples tested at levels of between 68–6,555 (µg/kg), and aflatoxin was detected in 2 samples heavily contaminated withAspergillus flavus. Moniliformin and tenuazonic acid were not detected in the samples tested. The implications of these findings for human and livestock health risk are discussed, together with possible strategies for controlling these pathogens.     

Mycotoxin-producing potential of fungi isolated from red kidney beans

The predominant fungi present in samples of reject and retail red kidney beans were Aspergillus glaucus, Penicillium spp. and Alternaria spp. Together with A. ochraceus, A. flavus, Fusarium spp., and Trichoderma, these isolates from the reject beans were screened for numerous mycotoxins by TLC. The most consistently produced mycotoxins were penicillic acid (from A. ochraceus and Penicillium spp.) and Alternaria toxins (tenuazonic acid and alternariol). A. glaucus strains were tested for cytotoxicity in three tissue culture cell lines with positive results.     

Index of potential contamination for schistosomiasis

Schistosomiasis occurs under a wide variety of climatic, geographical and other conditions. The basic reason for the transmission of schistosomes is, however, the low level of sanitation in endemic areas with the result that faeces or urine, or both, containing schistosome eggs get into water that contains freshwater snails susceptible to infection. Unfortunately, the degree of contamination of natural habitats with schistosome ova is difficult to estimate; consequently, there are few data on how much contamination, relative to a defined snail population density, is necessary to initiate or maintain transmission of schistosomiasis. This article discusses a little-used method to estimate the degree of contamination or transmission - the index of potential contamination (IPC). The expected changes in IPC after praziquantel treatment will be considered, as well as the level of reduction in IPC that might be needed to affect transmission or reduce morbidity.     

Fungal flora and aflatoxin contamination of feedstuff samples in Beida Governorate,Libya

Fungi of 19 genera, 30 species, and one variety were isolated from 25 samples of sheep-, cattle- and camel feedstuffs collected from different farms in the Beida Governorate, Libya.Aspergillus, Penicillium andFusarium were the most common genera in the three substrates tested. TLC was used to establish the identity of aflatoxins in the chloroform extract of all samples and the ability to produce aflatoxins byAspergillus flavus in a synthetic liquid medium. Twenty samples out of 25 tested were naturally contaminated and 21 isolates ofA. flavus out of 30 produced at least one of the following aflatoxins: B₁; B₁, G₁; and B₁, B₂, G₁, G₂. This is the first report about the natural occurrence of aflatoxins and aflatoxin-producers of the genusAspergillus in Libya.     

Exceptionally low blood glucose response to dried beans: comparison with other carbohydrate foods.

Normal volunteers took 50-g carbohydrate portions of eight varieties of dried legumes and 24 common foods drawn from grains, cereals and pasta, breakfast cereals, biscuits, and tuberous vegetables. Both the mean peak rise in blood glucose concentrations and mean area under the glucose curve of the subjects who ate beans were at least 45% lower than those of subjects who ate the other foods. These results suggest a potentially valuable role for dried leguminous seeds in carbohydrate exchanges for individuals with impaired carbohydrate tolerance.     

Mycoflora and mycotoxin-producing fungi of air-dust particles from Egypt

Using the dilution-plate method, 27 genera and 64 species were collected from 20 air-dust samples on glucose — (24 genera and 57 species) and cellulose — (21 genera and 45 species) Czapek's agar at 28 °C. There are basic similarities between the mycoflora of air-dust on the two media and the most prevalent species were Aspergillus niger, A. flavus, A. ochraceus, A. terreus, A. versicolor, Penicillium chrysogenum, P. funiculosum, Alternaria alternata, Cladosporium herbarum, Fusarium oxysporum, Rhizopus stolonifer and Trichoderma viride. Chaetomium globosum, Stachybotrys chartarum, Humicola grisea and Arthrobotrys oligospora were common only on cellulose agar plates.Extracts of mycelium from 25 isolates were tested with brine schrimp (Artemia salina); of these 23 displayed varying degrees of toxicity. Thin layer Chromatographic analysis of 12 isolates of Aspergillus flavus revealed that 4 strains were producing detectable aflatoxin. Zearalenone production was noted for 3 out of 5 strains of Fusarium oxysporum and 2 out of 5 strains of F. solani.     

Fungal chitinases: diversity,mechanistic properties and biotechnological potential

Chitin derivatives, chitosan and substituted chito-oligosaccharides have a wide spectrum of applications ranging from medicine to cosmetics and dietary supplements. With advancing knowledge about the substrate-binding properties of chitinases, enzyme-based production of these biotechnologically relevant sugars from biological resources is becoming increasingly interesting. Fungi have high numbers of glycoside hydrolase family 18 chitinases with different substrate-binding site architectures. As presented in this review, the large diversity of fungal chitinases is an interesting starting point for protein engineering. In this review, recent data about the architecture of the substrate-binding clefts of fungal chitinases, in connection with their hydrolytic and transglycolytic abilities, and the development of chitinase inhibitors are summarized. Furthermore, the biological functions of chitinases, chitin and chitosan utilization by fungi, and the effects of these aspects on biotechnological applications, including protein overexpression and autolysis during industrial processes, are discussed in this review.     

Analysis of potential contamination factors in musculoskeletal tissues

Tissue Banks have become the main source for bone grafts, due to preference for homologous tissues. Notwithstanding the use of aseptic techniques for procurement of tissues and judicious selection of donors, microorganisms are frequently found in procured bones. Purpose of this study is to evaluate the factors that increase safety of procurement and minimize discard of procured tissues. Microbiological contamination was analyzed in 1271 musculoskeletal tissues removed from 138 multi-organ donors over a period extending from 2006 to 2016. Effects of various risk factors related with contamination were estimated using a logistic regression model. Microbiological contamination rate in the tissues was 17.1%; low pathogenic microorganisms were cultivated in 12.9% of the tissues, while highly pathogenic ones were cultivated in 4.2% of the tissues. Evolution of one single team was monitored during that period, verifying a fall in the general contamination level from 22.5 to 9.2%. Absence of antibiotics increased low pathogenic contamination risk. Every additional day in intensive care unit (ICU) increased the risk of highly pathogenic contamination. Time elapsed between death and the beginning of removal procedures was found to be relevant for both low pathogenic and highly pathogenic microorganisms. Among the studied factors, the following contributed for a significant increase in contamination by microorganisms in removed tissues: lack of use of prophylactic antibiotic therapy in donors, quantity of removed tissues, length of admission in ICU and the time elapsed between aortic clamping and beginning of the removal procedure.     

Mercury biotransformations and their potential for remediation of mercury contamination

Bacterially mediated ionic mercury reduction to volatile Hg⁰ was shown to play an important role in the geochemical cycling of mercury in a contaminated freshwater pond. This process, and the degradation of methylmercury, could be stimulated to reduce the concentration of methylmercury that is available for accumulation by biota. A study testing the utility of this approach is described.Abbreviations Hg^R inorganic mercury resistance - Org-Hg organomercury - Org-Hg^R organomercury resistance - SRB sulfate reducing bacteria - Methyl-B12 methylcobalamine     

Fungal root endophytes of tomato from Kenya and their nematode biocontrol potential

The significance of fungal endophytes in African agriculture, particularly Kenya, has not been well investigated. Therefore, the objective of the present work was isolation, multi-gene phylogenetic characterization and biocontrol assessment of endophytic fungi harbored in tomato roots for nematode infection management. A survey was conducted in five different counties along the central and coastal regions of Kenya to determine the culturable endophytic mycobiota. A total of 76 fungal isolates were obtained and characterized into 40 operational taxonomic units based on the analysis of ITS, β-tubulin and tef1α gene sequence data. Among the fungal isolates recovered, the most prevalent species associated with tomato roots were members of the Fusarium oxysporum and F. solani species complexes. Of the three genes utilized for endophyte characterization, tef1α provided the best resolution. A combination of ITS, β-tubulin and tef1α resulted in a better resolution as compared to single gene analysis. Biotests demonstrated the ability of selected non-pathogenic fungal isolates to successfully reduce nematode penetration and subsequent galling as well as reproduction of the root-knot nematode Meloidogyne incognita. Most Trichoderma asperellum and F. oxysporum species complex isolates reduced root-knot nematode egg densities by 35–46 % as compared to the non-fungal control and other isolates. This study provides first insights into the culturable endophytic mycobiota of tomato roots in Kenya and the potential of some isolates for use against the root-knot nematode M. incognita. The data can serve as a framework for fingerprinting potential beneficial endophytic fungal isolates which are optimized for abiotic and biotic environments and are useful in biocontrol strategies against nematode pests in Kenyan tomato cultivars. This information would therefore provide an alternative or complementary crop protection component.     

Factors influencing the potential mobility and bioavailability of metals in dried lake sediments

Abstract

Samples taken from polluted creek sediments were dried at temperatures between 20°C and 100°C (either in air or under a nitrogen atmosphere) and selective chemical extraction procedures were then used to examine the effect of drying temperature and oxidation on the bonding mode distribution patterns of Zn, Pb, Cd and Cu. Exposure to air during the drying stage tended to increase the fraction of total metal which was less firmly bound (i.e. ion exchangeable, weakly sorbed). Less metal was present in these categories when higher drying temperatures were used, and temperature changes had a larger effect when the samples were dried under nitrogen. The drying process appears to promote metal migration to phases having a stronger bonding power. In most of the samples studied, heating caused Pb to migrate to the carbonate phase while accumulation in the organic/sulfide phases was the dominant process for Cu and Cd. In the case of Zn, migration to the carbonate phase was favoured in some studies (e.g. using air-dried samples), in other sediments the migration end-point was the organic/sulfide phases. During storage of dried samples at room temperature for prolonged periods (e.g. months) the amount of less firmly bound metal tended to increase, and nullified the distribution changes induced by drying. The effect was most pronounced in the case of Cd. The study highlights that significant errors in metal distribution pattern analyses can arise from sample preparation procedures and it has provided information on the possible mobilisation of metal when dredged sediment is land-dumped, i.e. allowed to dry in air.     

Stomatal diffusion resistance of snap beans. I. Influence of leaf-water potential

Concurrent measurements of abaxial and adaxial stomatal resistance and leaf-water potentials of snap beans (Phaseolus vulgaris L.) in the field and growth chamber show that the stomata on the 2 surfaces of the leaflet react differently to water deficit. The stomata on the abaxial surface, which are about 7 times more numerous than on the adaxial surface, are not significantly affected at leaf-water potentials greater than —11 bars, but with further decrease in leaf-water potential, the resistance rapidly increases. On the other hand, the resistance of the adaxial stomata increases sharply at a leaf-water potential of about —8 bars and is constant at higher water potentials. The average stomatal resistance for both surfaces of the leaf, which is the major diffusive resistance to water vapor, to a first approximation acts as an on-off switch and helps prevent further decline in leaf-water potential. The relation between the leaf-water potential and the stomatal resistance links the soil-water potential to the transpiration stream as needed for soil-plant-atmosphere models.