Mycotoxins are secondary metabolites of fungi affecting human and animal health. Five classes of mycotoxins are of major concern in animal husbandry, namely aflatoxins, trichothecenes, zearalenone, ochratoxins, and fumonisins. Due to their diverse structure these fungal toxins are able to cause a great variety of acute symptoms in animals. Clay minerals have been used in animal nutrition to bind mycotoxins, but the binders are only very specific for aflatoxins but not for other toxins. A novel strategy to control the problem of mycotoxicoses in animals is the application of microorganisms capable of biotransforming mycotoxins into nontoxic metabolites. The microbes act in the intestinal tract of animals prior to the resorption of the mycotoxins. A Eubacterium (BBSH 797) strain is able to deactivate trichothecenes by reduction of the epoxide ring (CAST, Mycotoxins, Risks in Plant, Animal and Human Systems, Task Force Report 139, Council of Agricultural Science and Technology, Ames Iowa 2003, p. 10.; Binder, E. M., Binder, J., Ellend, N., Schaffer, E. et al., in: Miraglia, M., van Egmond, H., Brera, C., Gilbert, J. (Eds.), Mycotoxins and Phycotoxins--Developments in Chemistry, Toxicology and Food Safety, Alaken, Fort Collins 1996, pp. 279-285). This strain was isolated out of bovine rumen fluid and the mode of action was proven in vitro and also in vivo. Further a novel yeast strain, capable of degrading ochratoxin A and zearalenone was isolated and characterized (Bruinink, A., Rasonyi, T., Sidler, C., Nat. Toxins 1999, 6, 173-177; Schatzmayr, G., Heidler, D., Fuchs, E., Mohnl, M. et al., Mycotoxin Res. 2003, 19, 124-128.) Due to the yeasts affiliation to the genus of Trichosporon and its property to degrade mycotoxins this strain was named Trichosporon mycotoxinivorans (Trichosporon MTV, 115).

Phytoremediation of soils polluted with polycyclic aromatic hydrocarbons (PAHs) has so far neglected the possible role of the ubiquitous symbiotic associations between plant roots and fungi known as arbuscular mycorrhizas. A time course laboratory experiment with clover and ryegrass grown on spiked [500 + 500 + 50 mg kg-1 of anthracene, chrysene and dibenz(a,h)anthracene] soil demonstrated for the first time that dissipation of condensed PAHs may be enhanced in the presence of arbuscular mycorrhiza [66 and 42% reductions in chrysene and dibenz(a,h)anthracene, respectively, versus 56 and 20% reductions in nonmycorrhizal controls]. Addition of a surfactant accelerated initial PAH dissipation but did not attain final PAH concentrations below those obtained with nonmycorrhizal plants. Toxicity tests (earthworm survival and bioluminescence inhibition in Vibrio fischeri) indicated that mycorrhiza reduced the toxicity of PAHs and/or their metabolites and counteracted a temporally enhanced toxicity mediated by surfactant addition. Phospholipid fatty acid profiles demonstrated that the imposed treatments altered the microbial community structure and indicated that the mycorrhiza-associated microflora was responsible for the observed reductions in PAH concentrations in the presence of mycorrhiza.

Crude oil-derived hydrocarbons constitute the largest group of environmental pollutants worldwide. The number of reports concerning their toxicity and emphasizing the ultimate need to remove them from marine and soil environments confirms the unceasing interest of scientists in this field. Among the various techniques used for clean-up actions, bioremediation seems to be the most acceptable and economically justified. Analysis of recent reports regarding unsuccessful bioremediation attempts indicates that there is a need to highlight the fundamental aspects of hydrocarbon microbiology in a clear and concise manner. Therefore, in this review, we would like to elucidate some crucial, but often overlooked, factors. First, the formation of crude oil and abundance of naturally occurring hydrocarbons is presented and compared with bacterial ability to not only survive but also to utilize such compounds as an attractive energy source. Then, the significance of nutrient limitation on biomass growth is underlined on the example of a specially designed experiment and discussed in context of bioremediation efficiency. Next, the formation of aerobic and anaerobic conditions, as well as the role of surfactants for maintaining appropriate C:N:P ratio during initial stages of biodegradation is explained. Finally, a summary of recent scientific reports focused on the removal of hydrocarbon contaminants using bioaugmentation, biostimulation and introduction of surfactants, as well as biosurfactants, is presented. This review was designed to be a comprehensive source of knowledge regarding the unique aspects of hydrocarbon microbiology that may be useful for planning future biodegradation experiments. In addition, it is a starting point for wider debate regarding the limitations and possible improvements of currently employed bioremediation strategies.

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