Acta microbiologica Hungarica最新文献

Distribution of aflatoxigenic moulds and aflatoxin B1 in Yugoslav dairy cattle feeds as well as the presence of aflatoxin B1 and M1 in raw milk, was tested. The experiments were carried out through three years (in all seasons). Samples were taken from state and private farms in Vojvodina. Feeds were contaminated in 83-100% with moulds. Fungi of farms in Vojvodina. Feeds were contaminated in 83-100% with moulds. Fungi of Aspergillus flavus-oryzae group were present permanently and the highest incidence of them was noticed during the third research year. Aflatoxin B1 was not found in the first year, but malt spent grains used for cows' feeding in summer of the second research year was contaminated with it (50.0 micrograms/kg). The same feed and pelleted sugar beet pulp were contaminated with aflatoxin B1 in winter, spring and summer of the third research year (5.0 to 16.0 micrograms/kg). Aflatoxin B1 and M1 were not found in raw milk through three-years investigations.

Kanamycin pretreatment through stomach tube eliminates the endotoxin producing Gram-negative bacteria of the intestinal flora and can delay the death of rats suffering from gastro-intestinal syndrome of radiation disease. Endotoxins probably play a significant role in the pathological process of the syndrome.

By using UV light 13 years ago from Trichoderma viride 8-7 Pers. ex S. F. Gray 82 colour and morphological mutants were prepared. The reversion of these mutants was high and in 1985 only 26 stable mutants (i.e. 32%) could be used for genetic studies. In 1991, from these 26 mutants we had only 6 stable types (i.e. 7.3% from the original state). These mutants were permanently transferred on fresh CzDA medium every 3-4 months and checked for morphology, growth, conidiation, heterokaryons and diploids production. The group of mentioned mutants was enlarged with mutants which were after 3-4 transfers on fresh medium, preserved dried to the present time. The largest differences were observed in microscopic appearance of colonies. Differences between growth rates, intensity of conidiation were comparable with those made 13 years ago.

Diazald, a chemical intermediate for the synthesis of biologically active compounds, was found to be a potent in vitro antimicrobial agent against yeasts, yeast-like and filamentous fungi as well as Gram-positive and Gram-negative bacterial strains. Its activity is not inhibited by either para-aminobenzoic acid (PABA) or the nitroso group-specific 2-aminothiazole-methoxyimino acetic acid (ATMAA). This suggests that the molecule as such is responsible for the antimicrobial activity. For its quick measurement a sensitive spectrophotometric method has been developed.

Old mice with thymus involution were treated intraperitoneally with a live vaccine containing a mesogenic strain of attenuated Newcastle Disease Virus or with Mannozym (M, 1% zymosan suspension). One day after the treatments mice were infected with lymphocytic choriomeningitis virus (LCMV) intracerebrally. The fatal course of the consequent LCMV infection was stimulated by each of the pretreatments, indicating that the cellular immune response was stimulated. The results are compared with results of experiments carried out on suckling, young adult and old mice in similar experimental systems. The authors' previous publication suggesting that the direction and degree of the immunomodulant effect may be influenced by the actual age-dependent condition of the lymphoid system, have been confirmed.

Coagulase-negative staphylococcal strains isolated from immunocompromised patients harboured in 41% non-MLS type lincomycin resistance determinant. Two kinds of resistance plasmids were detected in Staphylococcus epidermidis isolates of this origin in connection with lincomycin resistance. One of them represented by pBI1 and pBI84 (1.4 Md in size) determines no other resistance marker. The pBI109PGL plasmid determines also penicillinase production and aminoglycoside resistance, its molecular mass is 31 Md. Hybridization using linA, linA' and linA-like specific gene probes suggested occurrence of genes of lincosamid-inactivating enzyme belonging to the lin gene family but differring from the previously characterized determinants.

In this work the influence of 12 carbon and 9 nitrogen sources on pigment production of brown mutant Trichoderma viride M-108 was tested. There were two concentrations of nutrient sources used and the tests were carried out in three light regimes. The pigmentation was good only on media containing sodium nitrate, sodium nitrite, sucrose, starch and glycerol and there was no pigment production on media with adenine, ammonium chloride and ammonium sulphate. In mixtures of pigments, individual compounds were determined by using thin-layer chromatography and UV spectra of colour fractions.

Production of ochratoxin A (OA) by strains of Aspergillus ochraceus group (A. ochraceus--21, A. sclerotiorum--1, A. sulphureus--1) and Penicillium verrucosum var. cyclopium strains--11, on various media was investigated. Thirteen percent of A. ochraceus strains and 18% of P. verrucosum var. cyclopium formed OA growing on sterile crushed wheat for 14 days at 25 to 27 degrees C (preliminary experiments). Toxin concentrations were 5.0 to 7.0 micrograms/kg. Five strains OA-positive on crushed wheat and four OA-negative strains were cultivated on various liquid nutritional media (YES, RM, OAT, CG and AFP). All the strains tested, including OA-negative ones, produced OA on certain liquid media. Concentrations of OA were low again (trace to 16.0 micrograms/l). The largest number of mould strains examined produced OA on YES (55.5%) and RM media (44.0%), but the highest concentration (16.0 micrograms/l) was formed on YES and CG media.

A latex agglutination (LA) test was developed for the detection and measurement of polyclonal anti-adenovirus antibodies. Latex particles, coated with purified hexon, penton or fibre antigens displayed specific agglutination with 21 rabbit immune sera directed against the different antigens and the complete virus of 10 human and 2 animal adenovirus types. The sensitivity of LA was compared to that of passive haemagglutination, complement fixation (CF) and immunodiffusion reactions. In experiments with immune sera as well as with human serum samples the sensitivity of LA test proved to be in the same range as that of CF test. Because of its easy and rapid performance (slide agglutination within 4 min) LA method may substitute for CF reaction in serological adenovirus diagnosis.

Adult germfree (Gf) mice with undeveloped immune system due to antigen deficient environment, conventional (Cv) mice with normal immune system and Cv suckling mice with undeveloped immune system due to age were treated intraperitoneally with Mannozym (M, 0.1% zymosan suspension) 4 days or 4 days and 1 day before the intracerebral inoculation with lymphocytic choriomeningitis virus (LCMV). One dose of M was equal to 40 mg/kg of zymosan. In suckling mice, both applied doses of M contributed the development of fatal lymphocytic choriomeningitis after infection with 100 LD50 dose of LCMV, thus M pretreatment increased the cellular immune response to LCMV infection. M pretreatments had no influence on the course of LCMV infection either in adult Gf or in Cv mice. Spleen hypertrophy was caused by applied doses of M both in adult (Gf and Cv) and Cv suckling mice, but modulating effect on the cellular immune response manifested simultaneously only in Cv sucklings.