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Abstract

The aim of this study was to determine the effect of carfentrazone-ethyl (CE) doses of 0.265, 5.280, 10.560, 21.180, 42.240 μg kg-1 soil DM on fungi, Acnomycetes, organotrophic bacteria, total oligotrophic bacteria and spore-forming oligotrophic bacteria, and on the activity of dehydrogenases, catalase, urease, alkaline phosphatase, acid phosphatase, arylsulfatase and β-glucosidase. Carfentrazone-ethyl had a stimulating effect on total oligotrophic bacteria and organotrophic bacteria, but it inhibited the growth of Azotobacter, fungi, spore-forming oligotrophic bacteria and Actinomycetes. The analyzed substance modified the structure of soil microbial communities, and it induced the most profound changes in fungi. The highest values of the colony development (CD) index and the eco-physiological (EP) index were observed in organotrophic bacteria. The optimal dose of carfentrazone-ethyl stimulated the activity of dehydrogenases, catalase, urease, alkaline phosphatase, acid phosphatase and β-glucosidase, but it had no effect on arylsulfatase. The highest doses of the analyzed substance inhibited the activity of dehydrogenases (reduction from 11.835 to 11.381 μmol TPF), urease (reduction from 0.545 to 0.500 mmol N-NH4) and arylosulfatase (reduction from 0.210 to 0.168 mmol PNP). Dehydrogenases were most resistant to CE, whereas acid phosphatase and arylsulfatase were least resistant to the analyzed compound
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Abstract

In this study, selected heavy metals resistant heterotrophic bacteria isolated from soil samples at the Windmill Islands region, Wilkes Land (East Antarctica), were characterized. Phylogenetic analysis revealed affiliation of isolates to genera Bacillus , Lysinibacillus , Micrococcus and Stenotrophomonas . The strains were found to be psychrotolerant and halotolerant, able to tolerate up to 10% NaCl in the growth medium. The Minimum Inhibitory Concentration of the seven heavy metals Cr, Cu, Ni, Co, Cd, Zn, and Pb was deter − mined in solid media for each bacterial strain. Gram−positive Vi−2 strain and Gram−negative Vi−4 strain showed highest multiply heavy metals resistance, and Vi−3 and Vi−4 strains showed multi−antibiotic resistance to more than a half of the 13 used antibiotics. Plasmids were detected only in Gram−negative Vi−4 strain. The bacteria were able to produce different hydrolytic enzymes including industrially important proteases, xylanases, cellulases, and b −glucosidases. High heavy metals resistance of the Antarctic bacteria suggests their potential application for wastewater treatment in cold and temperate climates. Highly sensitive to Cd and Co ions Vi−1, Vi−5 and Vi−7 strains would be promising for developing biosensors to detect these most toxic heavy metals in environmental samples.
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Abstract

The paper addresses the effect of a compost prepared from tobacco wastes with an admixture of bark and straw on the enzymatic activity and certain chemical properties of a grey-brown podzolic soil amended with that compost. The study was conducted under the conditions of a pot experiment in which the soil material was collected from the surface horizon of the grey-brown podzolic soil. The effect of the application of the compost was compared with soil without such amendment. The test plant was maize cv. Kosmo 230. Fertilisation of the light soil with the compost studied caused changes in the enzymatic activity of the soil that were related both to the dose of the compost and to the kind of enzyme studied. With increase in the dose of the compost there was an increase in dehydrogenase activity (highest dose) and a significant decrease in the activity of acid phosphatase. Moreover, it was observed that tobacco compost was a significant source that enriched the light soil in organic matter, total nitrogen, and available forms of phosphorus, magnesium and potassium, which was evident in increased yields of maize grown as the test plant. Significant correlations were also demonstrated between a majority of the biochemical and chemical parameters, which indicates that those parameters characterise well the biological properties of a grey-brown podzolic soil amended with tobacco compost.
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