Irena Maliszewska

Production and some properties of lipase from Penicillium citrinum

Olive oil or Tween 80 stimulated the production of extracellular lipase by Penicillium citrinum. Olive oil at a concentration of 0.1% resulted in a sixfold increase in extracellular enzyme activity as compared with the basic medium. Lauric acid added to the basic medium inhibited the production of lipase. Almost no activity was found in an extract of mycelium. Among the fats that were tested, tributyrin was the best substrate for the P. citrinum lipase. The optimal activity was at pH 7.2 and 30°C. Enzyme activity was stable between pH 5.0 and 7.0 and in the temperature range from 10 to 40°C. NaCl and KCl at concentrations up to 1 M had no effect on lipase activity. Iron, magnesium, and calcium were found to have an inhibitory effect on enzyme activity. SDS and copper completely inhibited the enzyme activity.

The effect of culture conditions on lipolytic productivity of Penicillium citrinum

SummaryAn optimized medium for the production of extracellular lipase byPenicillium citrinum contained 5% peptone as the nitrogen source and 2% starch as the carbon source. The temperature of 22°C and pH 7.2 were most effective for lipolytic productivity. Rapeseed oil was used as an inducer.

Immobilization of lipase on various acrylic copolymers

Abstract Polymer carriers with various degrees of hydrophobicity, porosity, and polarity were studied for immobilization of lipase from Candida rugosa. Copolymers and terpolymers were prepared by suspension polymerization of six monomers, ethyl and butyl acrylate, acrylonitrile, methyl methacrylate, 2-hydroxypropyl methacrylate and vinyl acetate, and three crosslinking agents, divinylbenzene, ethylene glycol dimethacrylate and trimethylolpropane triacrylate, in the presence of various diluents. Immobilization of lipase was carried out via glutaraldehyde chemical binding or by adsorption. It was found that the best results were obtained for carriers of butyl acrylate, ethyl acrylate or 2-hydroxypropyl methacrylate crosslinked with ethylene glycol dimethacrylate.

Synthesis of 7-azabenzisoselenazol-3(2H)-ones: A new group of selenium containing antimicrobials

Abstract A convenient, general method for synthesis of various 2-substituted 7-azabenzisoselenazol-3(2H)-ones having pyridine ring condensed with selenazolone moiety is presented. It is based on the conversion of 2-chloronicotinic acid into 2-(chloroseleno)nicotinic acid chloride and its reaction with primary amines. The title compounds were found in the antimicrobial assay in vitro to be highly active against broad spectrum of bacteria and fungi.

Microbial Synthesis of Metal Nanoparticles

One of the most important aspects in researching nanotechnology is the synthesis of metal nanoparticles of well-defined sizes, shapes and controlled monodispersity. The most common methods of preparation are based on harsh chemicals, such as strong reducing agents, surfactants, polymer capping agents and, occasionally, organic solvent systems, to achieve better results. Therefore, there is a necessity to develop an environment friendly nanoparticle formation processes which do not use toxic chemicals in their synthesis protocols. Researchers in the field of nanoparticle synthesis have, in consequence, turned to biological systems for inspiration. The production of metal and metal alloy nanoparticles by microbes is a consequence of detoxification pathways. Majority of this biosynthesis occurs under ambient conditions. This is in sharp contrast to the caustic reagents, high temperatures and pressures that are modernly utilized for industrial synthesis of the same kinds of materials. Moreover, in many cases the nanomaterials are produced under genetic control resulting in specific morphologies, sizes and crystallinities of the structures.

Inhibitory and antimicrobial activities of OGTI and HV-BBI peptides, fragments and analogs derived from amphibian skin.

A series of linear and cyclic fragments and analogs of two peptides (OGTI and HV-BBI) isolated from skin secretions of frogs were synthesized by the solid-phase method. Their inhibitory activity against several serine proteinases: bovine β-trypsin, bovine α-chymotypsin, human leukocyte elastase and cathepsin G from human neutrophils, was investigated together with evaluation of their antimicrobial activities against Gram-negative bacteria (Escherichia coli) and Gram-positive species isolated from patients (Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus sp., Streptococcus sp.). The cytotoxicity of the selected peptides toward an immortal human skin fibroblast cell line was also determined. Three peptides: HV-BBI, its truncated fragment HV-BBI(3-18) and its analog [Phe(8)]HV-BBI can be considered as bifunctional compounds with inhibitory as well as antibacterial properties. OGTI, although it did not display trypsin inhibitory activity as previously reported in the literature, exerted antimicrobial activity toward S. epidermidis. In addition, under our experimental conditions, this peptide did not show cytotoxicity.

The Relationship between the Mechanism of Zinc Oxide Crystallization and Its Antimicrobial Properties for the Surface Modification of Surgical Meshes

Surgical meshes were modified with zinc oxide (ZnO) using a chemical bath deposition method (CBD) at 50 °C, 70 °C, or 90 °C, in order to biologically activate them. Scanning electron microscopy (SEM), mass changes, and X-ray diffraction measurements revealed that at low temperatures Zn(OH)2 was formed, and that this was converted into ZnO with a temperature increase. The antimicrobial activity without light stimulation of the ZnO modified Mersilene™ meshes was related to the species of microorganism, the incubation time, and the conditions of the experiment. Generally, cocci (S. aureus, S. epidermidis) and yeast (C. albicans) were more sensitive than Gram-negative rods (E. coli). The differences in sensitivity of the studied microorganisms to ZnO were discussed. The most active sample was that obtained at 90 °C. The mechanism of antimicrobial action of ZnO was determined by various techniques, such as zeta potential analysis, electron paramagnetic resonance (EPR) spectroscopy, SEM studies, and measurements of Zn(II) and reactive oxygen species (ROS) concentration. Our results confirmed that the generation of free radicals was crucial, which occurs on the surface of crystalline ZnO.

Deposition of one-dimensional zinc oxide structures on polypropylene fabrics and their antibacterial properties

In this article, a new method of modification of polypropylene fabric surface is presented, in order to obtain a material with antibacterial properties. The surface of the fabric is modified by direct deposition of the hexagonal zinc oxide rods onto the surface. For this reason, the influence of temperature on the size and morphology of microstructures of ZnO was investigated. Deposition was carried out at two temperatures, 75 and 90℃. The surface of the fabrics was treated with oxygen plasma. The influence of oxygen plasma on the parameters of rods was examined. The microstructure and crystalline structure of ZnO rods were investigated by scanning electron microscopy and X-ray diffraction. In addition, the impact of morphology and size of obtained ZnO structures on the biological activity of modified materials was determined. The tests revealed that the modified fabric shows very good antibacterial activity.

A View on the Organic Matter and Metalloporphyrins Biodegradation as Characteristic Components of Black Shale Ores

High content of organic compounds is characteristic for black shale-type ores. Metalloporphyrins are known as the most stable and resistant for biodestruction compounds of organic matter. Based on results obtained in previous studies, four metalloporphyrins were synthesised [1]. The experiments of biodestruction of organic matter extracted from polish black shale ore samples and of the synthetic metalloporphyrins were provided using autochthonous, heterotrophic bacteria mixtures isolated form polish black shale samples, and two Streptomyces species. It was found that biodestruction of black shale organic matter and copper- and vanadylporphyrins is possible, but it is a long term process. Porphyrins of Ni and Fe were resistant to biodegradation.

Antimicrobial activity and biodegradability of N -alkylaldonamides

A number of N-alkylaldo-namides, i.e., nonionic saccharide-based surfactants such as N-alkyl-N-methylgluconamides, N-alkyl-N-methyllactobionamides and N-alkyl-N,N’-bis[(3-D-aldonamidopro-pyl]amines were evaluated for environmental responses. All the N-alkylaldonamides were screened for antimicrobial activity against selected gram-positive (Staphylococcus aureus PCM 1944, Sarcina lutea PCM 1947, Bacillus subtilis PCM 1949, gram-negative (Escherichia coli PCM 2057, Serratia marcescens PCM 549, Pseudomonas putida PCM 2124) bacterial strains and some fungi (Saccharomyces cerevisiae, Penicillum citrinum, Aspergillus niger). It was generally recognized that the compounds tested were completely inactive towards fungi. N-Alkyl-N-methylgluconamides and N-alkyl-N-methyllactobionamides were practically inactive towards the bacteria studied. On the other hand, dicephalic saccharide-based surfactants were active against gram-positive cocci, much more strongly than the N-alkyl-N-methylaldonamides. Using the closed-bottle test (OECD guideline 301D), the biodegradability of these surfactants was determined. N-Alkyl-N-methyl-aldonamides may be considered to be readily biodegradable by activated sludge. The dicephalic surfactants studied showed slower biodegradation rates and they may be considered to be inherently biodegradable. Members of this class of saccharide surfactants exibit biological properties needed for environmental acceptance.