Françoise Seigle-Murandi

Influence of surfactants on solubilization and fungal degradation of fluorene

Eighteen fungal strains were tested in toxicity assays with surfactants in order to select surfactants and strains tolerant to surfactants for degradation assays. Two nonionic surfactants were used, an alkylphenol ethoxylate, Triton X-100, a sorbitan ester, Tween 80 and an anionic surfactant, sodium dodecyl sulfate. Solubilization and biodegradation tests were conducted in liquid medium batch; fluorene was quantified by HPLC. Results showed the enhancement of fluorene solubilization by the three surfactants, good tolerance of nonionic surfactants by the fungal strains and the enhancement of the biodegradation of fluorene by Doratomyces stemonitis (46-62%) and Penicillium chrysogenum (28-61%) in the presence of Tween 80 (0.324 mM) after 2 days.

Mutagenicity of substituted anthraquinones in the Ames/Salmonella microsome system

Unsubstituted anthraquinone, 4 substituted anthraquinones (emodin, danthron, physcion, a new compound M-108-C) and 3 dimers (skyrin, rugulosin, rugulin) were tested using the Ames/Salmonella assay (strains TA98, TA100, TA1537 and TA102). Danthron and emodin were found to be mutagenic for TA1537 with or without metabolic activation, physcion only with metabolic activation. A significant difference was found between the mutagenic activities of emodin (16.2 His+/nmole) and danthron (6.5 His+/nmole) as well as a high specific mutagenic activity for physcion (11.6 His+/nmole). These results on structure-mutagenic activity relationships suggest that the 6-methyl group plays an important role in the mutagenic activity after metabolic activation. Furthermore, and contrary to emodin, physcion exhibited a weak mutagenic activity for TA102, probably due to the formation of a different metabolite. Such information is necessary to evaluate the potential carcinogenic hazard of these compounds.

Mycoflora of soil around the Dead Sea. II: Deuteromycetes (except Aspergillus and Penicillium)

Summary Samples were taken from the top 10 centimeters of soils from 56 localities along the Dead Sea valley. There were 269 isolates representing 106 species dispatched into 51 genera of Deuteromycetes ( Aspergilius and Pesricillium not included) in addition to 20 sterile mycelia and an unidentified black yeast. The genera Alternaria, Ulocladium and Fusarium were represented respectively by 6, 8 and 10 different species and were the most frequently isolated in the different samples. The most common species were Acremonium strictum, Alternaria alternata, A. chlamydospora, Botryotrichum piluliferum, Botrytis cinerea, Cladosporium cladosporioides, Epicoccum nigrum, Fusarium oxysporum, Ulocladium atrum, U. chlamydosporum, U. consortiale . One new Bipolaris species was isolated, which has been the object of two other papers (submitted for publication). One thermophile was found: Scytalidium thermophilum . No strict halophiles but only halotolerant species were obtained. As already noticed in the first part of this work, there does not seem to be a fungus flora that is characteristic of desert soil or highly saline soil. Some ubiquitous soil fungi seem to be able to adapt to these extreme conditions.

Mycoflora of soil around the Dead Sea. I: Ascomycetes (including Aspergillus and Penicillium), basidiomycetes, zygomycetes

Summary Samples were taken from the top 10 centimeters of soils from 56 localities along the Dead Sea valley. There were 246 isolates representing 90 species dispatched into 23 genera of Ascomycetes (including Aspergillus and Penicillium ) and Zygomycetes in addition to some unidentified Ascomycetes and Basidiomycetes. The genera Aspergillus and Penicillium were represented by a great number of species. Two new species of Aspergillus ( niger group) and two new varieties of Microascus have been isolated. No strict thermophiles or halophiles were obtained. There does not seem to be a fungus flora that is characrerisric of desert soil or highly saline soil. Some ubiquitous soil fungi seem to be able to adapt to these extreme conditions.

Biodegradation potential of some micromycetes for pentachlorophenol.

A first screening was performed upon 100 strains of micromycetes cultivated on solid media (malt extract medium and mineral medium) with pentachlorophenol (PCP) (0.5 g/liter). Under these conditions, 50 strains gave a light blurring around the inoculation spot, indicating some PCP degradation. Later, 50 selected strains were cultivated in liquid synthetic medium with PCP (1 g/liter). After 6 days of cultivation, photodegradation occurred for 25%. On the whole, the consumption of PCP was 25% for Zygomycetes, 3% for yeasts, and 10-15% for Deuteromycetes, except 7% for Tuberculariales. It was shown that glucose repressed the PCP consumption. Among degrading fungi, some could grow with PCP when cultures were initiated with spores, others could not. A more detailed study was done with Phoma glomerata cultivated in liquid synthetic medium (PCP 100 mg/liter) in darkness or with light. Photodegradation increased up to 25% but abiotic degradation occurred also in darkness (8%). Consumption of PCP by Ph. glomerata was 27% after 2 days with light and was lower in darkness (19%).

Removal of PCNB from aqueous solution by a fungal adsorption process

Abstract Removal of PCNB from aqueous solutions by fungal mycelia was studied. Adsorption of the fungicide by dead biomass of M. racemosus, R. arrhizus and S. cyanescens was determined and compared with sorption on isolated cell walls of these three strains. Biosorptive uptake capacities are described by Freundlich equations of the form Qe=Kf·Cnfe. Measured values of Kf and nf indicate significant differences in the curve shapes and sorption capacities between the three species. Better performances were revealed by M. racemosus and R. arrhizus. Sorption of PCNB by cell walls alone was lower and statistically different from sorption by heat-killed mycelia thus corroborating that biosorption involved both uptake by the cell walls and by other cellular components.

Soil mycoflora from the Dead Sea Oases of Ein Gedi and Einot Zuqim (Israel)

Samples were taken from the top 10 cm of soils from 24 points in the Ein Gedi area. Among 329 isolates, 142 species were identified: 11 genera of ascomycetes, one genus of coelomycetes, 28 genera of hyphomycetes, 7 genera of zygomycetes and one yeast, in addition to some unidentified basidiomycetes. The hyphomycetes were represented by 17 dematiaceous, 9 mucedinaceous and two tuberculariaceous. Melanconiaceous and stilbellaceous genera were not found. Two new varieties of Microascus recently described were reisolated. No strict thermophiles or halophiles were obtained. There is apparently no very characteristic or specific fungal flora of the Dead Sea Oases although it was different from that found in the desert soil surrounding this area.

Degradation of Phenolic and Chloroaromatic Compounds by Coprinus spp.

Three species of Coprinus: C. sp, C. cinereus and C. micaceus were compared on solid media for some aspects of their physiological behaviour and cultural requirements (temperature, pH, substrate). Constitutive extracellular enzymatic activities were also determined. The Coprinus spp. exhibited different physiological and cultural features. Cultures of the 3 Coprinus species in synthetic liquid medium showed an efficient degradation of phenolic lignin model compounds (catechol, ferulic acid, guaiacol, phenol, protocatechuic acid syringic acid and vanillic acid) and pentachloronitrobenzene, while pentachlorophenol was not metabolized after 5 days perhaps because of a strong adsorption on mycelial biomass. It was suggested that phenoloxidases were not necessarily required for the metabolization of these compounds. Coprinus species may share a common degrading system for monomeric phenolic and chloroaromatic compounds.

Biotransformation and biosorption of pentachloronitrobenzene by fungal mycelia

The ability of Sporothrix cyanescens, Mucor racemosus and Rhizopus arrhizus to transform high concentrations of pentachloronitrobenzene, PCNB (100 mg l −1 ) in culture media was monitored by hplc analysis of the culture media over 20 d. The cultures of S. cyanescens and M. racemosus demonstrated high PCNB-transforming ability (78–81%), whereas removal of PCNB by R. arrhizus was less efficient. The removal of PCNB by each fungus was best illustrated when expressed as the ratio of the mass of chemical to the mass of mycelium, instead of medium concentration. Fungi removed > 50% of the PCNB within 48 h, and transformation products were revealed after 24 h. In addition, adsorption on fresh mycelia, as well as on lyophilized and oven-dried mycelia, of the three stains was measured. Fresh mycelium of M. racemosus had a mean adsorption value of 20·8 μg of PCNB mg −1 dry biomass during a 20 d period. For S. cyanescens and R. arrhizus low values were observed (0·5–2·5 μg mg −1 ). Adsorption values were dependent on species, physiological state, media and time. Removal of PCNB by S. cyanescens and M. racemosus was more efficiently controlled with living biomass and by biotransformation process, than by adsorption.

Growth of 1044 strains and species of fungi on 7 phenolic lignin model compounds

Growth of 1044 strains and species of micromycetes on 7 phenolic lignin model compounds as sole carbon source has been investigated. It was found that phenol inhibited growth, followed by catechol and guaiacol. Protocatechuic, vanillic, syringic and ferulic acids allowed the highest growth. Most of the fungi grown on protocatechuic, vanillic, ferulic and syringic acids produced normal fructifications whereas fructification was perturbed on guaiacol and phenol. Guaiacol, syringic acid and catechol were the strongest pigment inducers. Generally fungi imperfecti had a good growth on phenolics, however only a limited number of Yeasts could use these compounds. It appears that the biodegradability of the phenolic compounds declined with the decrease of their water solubility.