Isabel M. Santos

Biodegradation of bioaccessible textile azo dyes by Phanerochaete chrysosporium

Azo dyes are important chemical pollutants of industrial origin. Textile azo dyes with bioaccessible groups for lignin degrading fungi, such as 2-methoxyphenol (guaiacol) and 2,6-dimethoxyphenol (syringol), were synthesised using different aminobenzoic and aminosulphonic acids as diazo components. The inocula of the best biodegradation assays were obtained from a pre-growth medium (PAM), containing one of the synthesised dyes. The results of the dye biodegradation assays were evaluated every 7 days, by the decrease of the absorbance at the maximum wavelength of the dye, by the decrease of the sucrose concentration in the culture medium and by the increase of the biomass during the 28 days of assay. It was observed that the extent of dye biodegradation depended on the sucrose concentration, on the degraded dye structure and, on the dye present in the PAM medium.

The effect of culture preservation techniques on patulin and citrinin production by Penicillium expansum Link

Aims: To study the influence of culture preservation methods and culture conditions on the production of the mycotoxins patulin and citrinin by Penicillium expansum. u2028Methods and results: Ten strains of Penicillium expansum were preserved using subculture and maintenance at 4u2003°C, mineral oil, drying on silica gel and freeze‐drying. Patulin and citrinin production was assessed on yeast extract sucrose agar (YES) and grape juice agar (GJ), using TLC before and after 0·5, 2–3, 6 and 12u2003months preservation. Citrinin was detected in all cultures for all preservation techniques on YES. The patulin profiles obtained differed with strain and culture media used. u2028Conclusions: Citrinin production seems to be a stable character for the tested strains. There is a tendency for patulin detection with time apparently more consistent for silica gel storage and freeze‐drying, especially when the strains are grown on GJ. u2028Significance and Impact of the Study: Variability in the profiles of the mycotoxins tested seems to be more strain‐specific than dependent on the preservation technique used.

FISH AND CALCOFLUOR STAINING TECHNIQUES TO DETECT IN SITU FILAMENTOUS FUNGAL BIOFILMS IN WATER

Filamentous fungi are a ubiquitous and diverse group of eukaryotic organisms and may contribute, along with bacteria, yeasts, protozoa and viruses, to the formation of biofilms in water distribution systems. However, fungal involvement in biofilms has not been demonstrated unambiguously. Furthermore, these fungi may be responsible for the production of tastes, odours and mycotoxins in drinking water making their early detection important. The detection of fme these problems a combination of two fluorescent techniques for direct detection was tested: (a) Fluorescence In Situ Hybridization (FISH) employing the universal rRNA probe EUK516, labelled with the red Cy3, followed by (b) staining with Calcofluor White MR2 fluorescent dye which stains fungal cell walls blue. Pure cultures of Penicillium brevicompactum were used to establish the methods followed by separate experiments with real water biofilm samples in PVC-C and cast iron coupons. FISH demonstrated eukaryotic microrganisms after approximately 5 h while the calcofluor method revealed chitinous filamentous structures in less than one hour. When the two methods were combined, additional resolution was obtained from the images of filamentous walls (blue) with intact protoplasm (red). In conclusion, FISH and Calcofluor staining provide rapid, direct and unambiguous information on the involvement of ff in biofilms which form in water.

Criteria followed in the establishment of a filamentous fungal culture collection – Micoteca da Universidade do Minho (MUM)

In Portugal there are few culture collections of filamentous fungi and these are mostly in-house, and located mainly in the Lisbon area. Furthermore, open access to Portuguese databases on microorganisms is not well established. This knowledge and the continuing experimental activity in mycology, combined with an interest from the University in creating and financing reliable services to support research, led to the organization of a filamentous fungal culture collection, hosted at the Biological Engineering Centre of Minho University, in the North of Portugal. The Micoteca da Universidade do Minho (MUM), was established in 1996, with the aim of maintaining and providing strains for research on biotechnology and for use in teaching laboratories, and to act as a centre of expertise, information and training, complying with international quality standards. The use of a computerized system for the management of recorded data and the collections holdings was envisaged from the start. The collection now holds 128 identified species, including recognized standard or test strains and isolates derived from research activities, mainly of the genera Penicillium and Aspergillus. The microbial strain database was built in-house and runs on Windows 2000. To ensure widespread availability of details of the collections holdings, the fields intended for general searching and viewing are available on-line at http://www.micoteca.deb.uminho.pt/.

New and simple plate test for screening relative transfructosylation activity of fungi

Several microorganisms are reported to have transfructosylation activity due to fructosyltransferase and/or fructofuranosidase activities. However, the search for other fungi with higher transfructosylation activity remains a challenge. So, a presumptive and indirect colorimetric plate assay for the evaluation of transfructosylation activity in fungi was developed which involved the simultaneous determination in the same plate of glucose and fructose released from sucrose. The method entailed the (a) glucose oxidase-peroxidase coupled reaction using phenol and 4-aminoantipyrine for determination of glucose; and (b) fructose dehydrogenase oxidation in the presence of a tetrazolium salt for determination of fructose. The presence of enzymes with transfructosylation activity was identified by the formation of pink (presence of glucose) and blue (presence of fructose) halos around the fungal colony. In conclusion, the results showed that the method is suitable for screening a large number of fungi due to its simplicity, reproducibility and rapidity and also gives a relative quantitative idea of the transfructosylation activity of different fungi species.