Marek Kolenčík

Fungal volatilization of trivalent and pentavalent arsenic under laboratory conditions.

Production of volatile derivatives of arsenic was studied using pure cultures of different fungal strains under laboratory conditions. Arsenic was used in its trivalent and pentavalent forms to evaluate the effect of arsenic valency on its biovolatilization. The average amount of volatilized arsenic for all fungal strains ranged from 0.026 mg to 0.257 mg and 0.024 mg to 0.191 mg of trivalent and pentavalent arsenic, respectively. These results show that approximately 23% of arsenic was volatilized from all culture media originally enriched with approximately 4 and 17 mg L(-1) of arsenic in trivalent form. The average amount of biovolatilized arsenic from culture media originally enriched with 4 and 17 mg L(-1) of arsenic in pentavalent form was 24% and 16%, respectively. The order of ability of arsenic biovolatilization is Neosartorya fischeri > Aspergillus clavatus > Aspergillus niger. Toxicity and fungal resistance to trivalent and pentavalent arsenic were also evaluated based on radial growth and biomass weight.

Removal of arsenic from aqueous environments by native and chemically modified biomass of Aspergillus niger and Neosartorya fischeri

Arsenic removal from aqueous solutions by biomass of two fungal strains, Aspergillus niger and Neosartorya fischeri, was assessed. The biosorption capacity of fungal biomass was studied within the As(V) concentration range of approximately 0.2 to 5.0 mg L−1 at two different pH values (pH 5 and 7). With increasing initial arsenic concentration, the biosorption capacity of both fungal strains increased almost linearly and achieved the sorption capacity of 0.317 and 0.124 mg g−1 for biomass of N. fischeri and A. niger, respectively. The effect of biomass treatment with FeCl3 and HCl on As(III) and As(V) uptake was also studied. The optimum biosorption pH as well as the effect of biomass treatment was found to be dependent on the fungal strain used. Treatment with FeCl3 and HCl did not result in any significant increase in arsenic uptake. To the contrary, treatment with ferric oxyhydroxide was found to be very effective and virtually 100% of the arsenic was removed from the samples of contaminated natural water.

Physiological response of culture media-grown barley (Hordeum vulgare L.) to titanium oxide nanoparticles

ABSTRACT Since the fate of nanoparticles after their release in the environment and their possible transfer in plants and subsequent impacts is still largely unknown, this paper evaluates the potential phytotoxic effects of up to 20% w/w TiO2 nanoparticles (nTiO2) on barley cultivated in hydroponics and agar media. The X-ray diffraction analysis confirmed that nTiO2 powder corresponds to anatase phase. On agar medium only high concentrations of nTiO2 (10% and 20% w/w) induced significant inhibition of shoot growth. However, hydroponics treatment with nTiO2 up to 1000 mg L−1 did not show any adverse effect on the shoot growth. In both experiments, (i) root growth inhibition effects became visible with increasing concentration of nTiO2, (ii) plants treated with nTiO2 showed no change in chlorophyll a and b content, even though the plants absorbed nTiO2, (iii) weight of biomass treated with nTiO2 was not significantly different compared to control. Therefore, we assume that transport of nTiO2 into the aerial parts is limited due to the presence of effective mechanical or physiological barriers in roots. Overall, it appears that early root growth is a relevant indicator of potential effects of nTiO2 exposure. Our results also indicate that synthesized nTiO2 are not significantly toxic to the barley when applied at the concentrations used in this work, even though plants absorb titanium.

Soil organic matter quantity and quality of land transformed from arable to forest

Comparative studies on quantitative and qualitative characteristics of soil organic matter were studied in arable and afforested in 1964 Stagni-Haplic Luvisol in Arboretum Mlyňany (Slovakia). The studies were conducted at three stands – arable soil located next to Arboretum (control), under thuja trees (Thuja orientalis L.) and under junipers (Juniperus Chinensis L.). Results of the studies showed, that in A horizons, 50 years of thuja and juniper trees growing on formerly arable land, had resulted to the significant (by 69% under thuja and by 126% under juniper) increase of total organic carbon (Cox) compared to control arable land. KMnO4 oxidisable carbon (CL) and mainly hot water-soluble carbon (Chwd) had higher contents in soil under studied trees than on arable land. The conversion of cropland to forest led to lowering of soil organic matter quality, assessed as the ratio of total carbon and nitrogen (Cox/NT), which was in arable soil 10.2, under thuja trees 13.9 and under junipers 12.0. Surprisingly, the quality of humus between examined sites differed only minimally, since the change of humus quality is a long term process.

Heterotrophic bacterial leaching of zinc and arsenic from artificial adamite

Artificial adamite [Zn2(AsO4)(OH)] is a convenient structural model because it is isostructural with other rock-forming minerals in secondary ore deposits formed in cementation zones. Microbial activity in these zones accelerates mineral biogeochemical deterioration and metal release, and our results confirmed that Pseudomonas, Rhodococcus and Cupriavidus strains accelerate adamite leaching by 10 to 465 times compared to controls. Here, the Pseudomonas chlororaphis ZK-1 bacterial strain in a static 42-day cultivation proved more effective than Rhodococcus and Cupriavidus by leaching over 90% arsenic and 10% zinc from adamite in one-step in vitro. We evaluated adamite with the VESTA visualization system for electronic and structural analysis, and our results enhance understanding of zinc and arsenic biogeochemical cycles and mobilization, and highlight bacteria’s beneficial natural and biotechnological application in environmental geochemistry and biohydrometallurgy.

Erratum to: Antimicrobial bionanocomposite–from precursors to the functional material in one simple step

In the published manuscript http://dx.doi.org/10.1007 /s11051-016-3664-y, the minimal inhibitory concentration (MIC) value for the monitored composites is incorrectly stated: 0.014 mg/ml is the stated value while the correct value is 0.14 mg/ml. The incorrect value does not influence the general concept of the article, its other results or its conclusions, nor it demands an in-depth revision of the published text. J Nanopart Res (2017) 19: 244 DOI 10.1007/s11051-017-3938-z