Régine Steiman

Biodegradation Of Anthracene And Fluoranthene By Fungi Isolated From An Experimental Constructed Wetland For Wastewater Treatment

Pilot-scale constructed wetlands were used to treat water contaminated by polycyclic aromatic hydrocarbons (PAHs), particularly fluoranthene, and the possible role of fungi present in these ecosystems was investigated. A total of 40 fungal species (24 genera) were isolated and identified from samples (gravel and sediments) from a contaminated wetland and a control wetland. All of them were assayed for their ability to remove anthracene (AC) and fluoranthene (FA) from liquid medium. FA was degraded efficiently by 33 species while only 2 species were able to remove AC over 70%. A selection of 10 strains of micromycetes belonging to various taxonomic groups was further investigated for FA and AC degradation, toxicity assays and phenoloxidases (POx) detection. Interesting and not previously reported species were revealed (Absidia cylindrospora, Cladosporium sphaerospermum, and Ulocladium chartarum). They were all able to highly degrade the PAH-model compounds chosen. An interesting inducibility was noted for Ulocladium chartarum. Degradative ability of fungi was not related to their extracellular POx activity. This study may contribute to the improvement of constructed wetlands for water treatment, which may be enriched in efficient fungi.

In vitro antioxidant and antigenotoxic potentials of myricetin-3-o-galactoside and myricetin-3-o-rhamnoside from Myrtus communis: modulation of expression of genes involved in cell defence system using cDNA microarray.

Antioxidant activity of myricetin-3-o-galactoside and myricetin-3-o-rhamnoside, isolated from the leaves of Myrtus communis, was determined by the ability of each compound to inhibit xanthine oxidase activity, lipid peroxidation and to scavenge the free radical 1,1-diphenyl-2-picrylhydrazyl. Antimutagenic activity was assessed using the SOS chromotest and the Comet assay. The IC50 values of lipid peroxidation by myricetin-3-o-galactoside and myricetin-3-o-rhamnoside are respectively 160 microg/ml and 220 microg/ml. At a concentration of 100 microg/ml, the two compounds showed the most potent inhibitory effect of xanthine oxidase activity by respectively, 57% and 59%. Myricetin-3-o-rhamnoside was a very potent radical scavenger with an IC50 value of 1.4 microg/ml. Moreover, these two compounds induced an inhibitory activity against nifuroxazide, aflatoxine B1 and H2O2 induced mutagenicity. The protective effect exhibited by these molecules was also determined by analysis of gene expression as response to an oxidative stress using a cDNA micro-array. Myricetin-3-o-galactoside and myricetin-3-o-rhamnoside modulated the expression patterns of cellular genes involved in oxidative stress, respectively (GPX1, TXN, AOE372, SEPW1, SHC1) and (TXNRD1, TXN, SOD1 AOE372, SEPW1), in DNA damaging repair, respectively (XPC, LIG4, RPA3, PCNA, DDIT3, POLD1, XRCC5, MPG) and (TDG, PCNA, LIG4, XRCC5, DDIT3, MSH2, ERCC5, RPA3, POLD1), and in apoptosis (PARP).

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.

First survey of fungi in hypersaline soil and water of Mono Lake area (California)

Mono Lake is a closed lake located in central California, east of the Sierra Nevada mountains. It contains dissolved carbonates, sulfates and chlorides at high concentrations. Due to its high salinity, Mono Lake was sometimes compared to the Dead Sea. However, it appears that Mono Lake water and vicinity abound with life. In this work, the fungal flora living in this extreme ecosystem was studied for the first time. Soil, tufa, water and sediment samples were also analyzed for their mineral and salt composition. Results showed that water was particularly rich in sodium, potassium, phosphorus and boron. Soil and sediments contained very high levels of calcium and magnesium, but also barium, boron and strontium. Sodium, phosphorus and iron levels varied in a large extent from one to another sample. Neutral to very alkaline pH were recorded. Water samples were found sterile in the conditions chosen for fungi isolation, while sediment, soil and tufa samples led to the isolation of a total of 67 fungal species (from 23 samples), belonging to various taxonomic groups. From our results no clear effects of the chemical parameters of the samples were observed on fungal life apart from the pH. The methods chosen did not allow the isolation of extremely halotolerant species. We isolated in this work a series of ubiquitous species, suggesting that a selection of resistant and/or adaptable strains of some common species could have occurred. Depending on the medium and the temperature of isolation, it can be hypothesized that some species were present as dormant structures, while some others, isolated at pH 8 on a medium enriched in Na and Ca, could be in a growing form adapted to alkaline and saline conditions. This work contributes to a better knowledge of the mycobiota present in the Mono Lake’s ecosystem.

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%).

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.

Liquid chromatography study of degradation and metabolism of pentachloronitrobenzene by four soil micromycetes

Abstract The pentachloronitrobenzene (PCNB) biodegradation by four soil micromycetes, Mucor racemosus, Sporothrix cyanescens, Paecilomyces farinosus and Pithomyces chartarum was studied after 24 h and 120 h. Quantitation of PCNB and identification of its metabolites were monitored by LC analysis of the culture media on a 5 μm Adsorbosphere HS C 18 column with methanol/water (93:7) pH 3.5 (1.0 ml/min) and UV detection at 301 nm. The extraction process of PCNB and its metabolites was performed on an Extrelut® cartridge with ethyl acetate as eluent. Strains were able to degrade PCNB with high efficiency. Five metabolites were identified : pentachloroaniline, tetrachloroaniline, pentachlorothiophenol, pentachlorothioanisole and pentachloroanisole. Based on our findings, three metabolic pathways were retained.