J. Gabriel

Effect of Heavy Metals on the Growth of Selected Wood-Rotting Basidiomycetes*

Mercury, cadmium and cobalt were found to be the most toxic heavy metals, inducing strong growth inhibition of the tested basidiomycetes. The studied species differed significantly in their sensitivity to cadmium. The most sensitive fungus,Inonotus obliquus, did not grow at Cd concentrations higher than 0.1 mmol/L, whereasStereum hirsutum grew at more than 2 mmol Cd/L. Changes in mycelial morphology were observed inS. hirsutum andTrametes versicolor cultivated in the presence of cadmium and mercury. The toxicity of heavy metals was lower in rich, complex media.

Microemulsion electrokinetic chromatography of diphenylhydrazones of dicarbonyl sugars

A mixture of diphenylhydrazones of dicarbonyl sugars was separated by microemulsion electrokinetic chromatography. Separations were carried out with a laboratory-made capillary electrophoresis apparatus using an untreated fused-silica capillary [70 cm (effective length 65 cm)×50 μm I.D.] at 20 kV; detection was at 220 nm. The microemulsion system was composed of 5 mM borate buffer, pH 8.0 (89.27%, w/w), sodium dodecyl sulphate (SDS; 3.31%, w/w), n-butanol (6.61%, w/w) and n-octanol (0.81%, w/w). Separation by microemulsion electrokinetic chromatography was significantly better then separation obtained by routine micellar electrokinetic chromatography with SDS and was characterized by a much higher efficiency (theoretical plates ranged from 100·103 to 254·103). SDS–micellar electrokinetic chromatography resolved only one compound from a joint peak of two sugars and from a cluster peak consisting of seven compounds. Applicability to the analysis of biological samples was also demonstrated.

Effect of cadmium on the ligninolytic activity ofStereum hirsutum andPhanerochœte chrysosporium

An inhibitory effect of cadmium on the growth and ligninolytic activity of the wood-rotting basidiomycetesPhanerochœte chrysosporium, Pleurotus ostreatus, Pycnoporus cinnabarinus andStereum hirsutum was observed. Delayed decolorization of the polymeric dye Poly R-478 was observed in samples with 0.10 mmol/L Cd. Addition of 0.25 mmol/L Cd to the cultivation medium strongly reduced the activity of both Mn-dependent and Mn-independent peroxidases ofStereum hirsutum, while the activity of laccase was not affected to a similar extent. The maximum of MnP activity in these samples was found during the exponential phase of growth whereas control samples showed the highest activity after the onset of the stationary phase (days 15–21). Cadmium at concentrations higher than 0.50 mmol/L significantly inhibited the activity of all enzymes tested in bothS. hirsutum andP. chrysosporium.

Variability of Laccase Activity in the White-Rot Basidiomycete Pleurotus ostreatus

The production of laccase in liquid cultures of the white-rot fungusPleurotus ostreatus was highly variable. During the first days of cultivation, the relative variability was as high as 80–100% and it decreased to 30% in the course of cultivation. The main source of variability was assumed to be the independent development of enzyme activity in individual cultures. Cultures with high laccase production showed also high production of the other ligninolytic enzyme—Mn-dependent peroxidase. The variability was probably due to the source of inoculum, deactivation of the enzyme in culture liquid and genetic variations among the cultures. Variability of laccase activities was lower during solid-state fermentation on wheat straw and during the growth in nonsterile soil.

Degradation of polycyclic aromatic hydrocarbons by the copper(II)-hydrogen peroxide system

A non-enzymic system containing CuSO4 (10 mmol/L) and hydrogen peroxide (100 mmol/L) was used for the degradation of three polycyclic aromatic hydrocarbons: phenanthrene, fluoranthene, and pyrene (all at 10 mmol/L). The system degraded the compounds rapidly and efficiently. After 1 d at room temperature, more than 80 % of pyrene, phenan-threne, and fluoranthene disappeared. Several products are formed during the reaction including a black precipitate.

Bacterial degradation of the herbicide bromoxynil byAgrobacterium radiobacter in biofilm

The bromoxynil-degrading soil microorganismAgrobacterium radiobacter was used for degradation of the herbicide under nonsterile batch and continuous conditions. From four types of carrier particles, beech shavings showed the best stability of the bacterial biofilm, bromoxynil concentration in a column reactor decreasing to 65% after 5 d. The efficacy of degradation was enhanced by addition of ferrous, cobaltous or cupric ions.

Degradation of 2-chlorobenzoic and 2,5-dichlorobenzoic acids in pure culture by Pseudomonas stutzeri

A strain ofPseudomonas stutzeri KS25 utilizing 2-chlorobenzoic and 2,5-dichlorobenzoic acids as the sole carbon and energy source was isolated from polychlorophenol-contaminated soil and sewage, using the method of enrichment cultures. This strain was also able to grow on 2-fluoro-, 2-iodo-, 2-bromo- and 2,5-dihydroxybenzoate, but did not utilize 3-, 4-chloro-, 2,4- and 2,6-dichlorobenzoates as the sole carbon and energy source, however, it cometabolized 3-chloro-, 2,4-and 2,6-dichlorobenzoates, but not 4-chlorobenzoate. The yield of released chlorine during utilization of 2-chloro- and 2,5-dichlorobenzoates amounted to 100 % of the theoretical. The concentration of 2-chloro- and 2,5-dichlorobenzoates, not substantially inhibiting the isolated microorganism, was within the range 0.25–0.5 and 2.5–3.0 g/L, respectively.

Primary fluorescence (Autofluorescence) of fruiting bodies of the wood-rotting fungusFomes fomentarius

Autofluorescence of fruiting bodies of the wood-rotting fungusFomes fomentarius has been observed and is described among native macrofungi for the first time. The strongest yellow autofluorescence with blue excitation was displayed by pith sets, a weaker yellow, yellow-green to yellow-red fluorescence was due to generative thin-walled hyphae while the weakest yellow-reddish fluorescence was emitted by thick-walled skeletal hyphae (though their parts may emit a more intensive yellow fluorescence). This yellow, yellow-green to yellow-red autofluorescence was assessed to be more intensive than the emission described so far in bacteria and fungi (except for lysed hyphae of the fungusTrametes versicolor). With green excitation allF. fomentarius cells emitted strong red autofluorescence.

Antifungal effects of new heterocyclic compounds, 6H-pyrimido[2,1-a]isoindole derivatives

Minimal inhibitory concentrations for 10 new condensed isoindole derivatives were established by the agar diffusion method. Benzo[b]-6H-pyrimido[2,1-a]isoindole-4-one exhibited a broad antifungal effect; the observed MIC (mg/L) were 7 (K. lactis), 8 (C. pseudotropicalis), 17 (W. fluorescens), 22 (E. magnusii), 31 (P. membranaefaciens), 32 (S. alluvius) and 32 (S. cerevisiae). The compound also inhibited the growth ofB. subtilis (MIC 9 mg/L). No effect on the growth ofE. coli was found.

Antifungal properties of substituted 1-phenyl-5-mercaptotetrazoles and their oxidation product, 5-bis-(1-phenyltetrazolyl) disulfide.

The antifungal effect of substituted 1-phenyl-5-mercaptotetrazoles was tested withCandida tropicalis, C. pseudotropicalis, C. mogii, Trichosporon cutaneum, Cryptococcus albidus andS. cerevisiae. Candida strains exhibited the lowest sensitivity to the compounds; the most sensitive wasS. cerevisiae. The MIC values ranged from 40 to >1000 mg/mL. The antifungal effect of halogenated compounds decreased in the series of bromo > chloro > fluoro derivatives. The electrochemical oxidation of substituted 1-phenyl-5-mercaptotetrazole derivatives in an acetonitrile medium was studied as a model for the enzymic oxidation of the substance, including study of the effect of water, perchloric and trifluoromethanesulfuric acids onE1/2 andI1. 5-Bis-(1-phenyltetrazolyl)disulfide, the compound with no antifungal effect, has been identified as the main oxidation product of 1-phenyl-5-mercaptotetrazole.