Antibiotic Resistance in Metal-Tolerant Microorganisms from Treatment Facilities.

The study examines the antibiotic resistance of metal-tolerant bacteria isolated from the wastewater treatment plant of a large city to six antibiotics belonging to the ß-lactam antibiotics, aminoglycosides and amphenicols. Resistance of bacteria from sewage sludge multitolerant to heavy metals to 18 antibiotics of the ß-lactam antibiotics, tetracyclines, aminoglycosides, diaminopyrimidines, amphenicols and ansamycins was studied also. Out of 10, the metal-tolerant microorganisms isolated from wastewater treatment facilities only the Klebsiella pneumonia strain (tolerant to 3 mM Cu) from the sludge of a secondary settling tank did not show resistance to the studied antibiotics at the concentrations considered. Resistance to the maximum amount of antibiotics was typical for strains Serratia fonticola SS0-1, isolated from fresh sewage sludge and resistant to 5 mmol Cu and 3 mmol Pb, or Stenotrophomonas maltophilia SS0-5, also isolated from fresh sludge and resistant to 3 mmol Zn and Cu. It is possible that bacterial resistance to antibiotics develops not only as a result of the use of antibiotics themselves, but also as a result of environmental pollution with heavy metals, and vice versa.

Trace elements adsorption by natural and chemically modified humic acids.

Humic substances with or without chemical modification can serve as environmentally benign and inexpensive adsorbents of potentially toxic trace elements (PTTEs) in the environment. The present study investigated the absorption of Pb, Zn, Cu and Ni by natural and potassium persulfate (K2S2O8) modified humic acids (HAs) isolated from a lowland peat through batch experiments. The adsorption of the studied PTTEs on the natural HA was satisfactorily described by the Langmuir isotherm model with maximum monolayer adsorption capacities of 318.2, 286.5, 225.0 and 136.8 mmol/kg for Pb, Cu, Zn and Ni, respectively. A thorough characterization of the natural and modified HA using 13C nuclear magnetic resonance spectroscopy demonstrated that the chemical modification of natural HA with K2S2O8 led to an increase in the content of carboxyl groups, and ketone and quinoid fragments in the HA structure. Consequently, the modified HA absorbed 16.3, 14.2, 10.6 and 6.9% more Pb, Ni, Zn and Cu, respectively, than the original natural HA. The isotherm data modeling together with adsorbent characterization suggested that the adsorption of PTTEs was controlled mainly by chemisorption mechanisms where inner-sphere complexations of metal ions with HA functional groups took place.

Fungicidal Properties of 2-Amino-4-nitrophenol and Its Derivatives.

Fungicidal effect of 2-amino-4-nitrophenol and its derivates, prepared by replacing the hydrogen atom in its amino group by different organic radicals was studied. Evaluation of the biological activity of studied substances by сomputational chemistry methods was performed. Toxicity of 2-amino-4-nitrophenol and synthesized N-(2-hydroxy-5-nitrophenyl)formamide and N-(2-hydroxy-5-nitrophenyl)acetamide to six species of phytophatogen fungi were tested in the experiment. The results of the study demonstrate that replacement of the hydrogen atom in the amino group by a aldehyde group leads to an increase in fungicidal activity with respect to Rhizoctonia solani and Bipolaris sorokiniana. A replacement of the hydrogen atom by a ketone group increases the inhibitory effect on Sclerotinia sclerotiorum and Venturia inaequalis. The paper contains comparative data on the fungicide effect of commercial preparation for studied fungi also.