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Biochemical and cellular properties of Gluconacetobacter xylinus cultures exposed to different modes of rotating magnetic field

Fijałkowski K., Drozd R., Żywicka A., Junka A. F., Kordas M., Rakoczy R.

Polish Journal of Chemical Technology

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2017

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Vol. 19, nr 2

107--114

EN

The aim of the present study was to evaluate the impact of a rotating magnetic field (RMF) on cellular and biochemical properties of Gluconacetobacter xylinus during the process of cellulose synthesis by these bacteria. The application of the RMF during bacterial cellulose (BC) production intensified the biochemical processes in G. xylinus as compared to the RMF-unexposed cultures. Moreover, the RMF had a positive impact on the growth of cellulose-producing bacteria. Furthermore, the application of RMF did not increase the number of mutants unable to produce cellulose. In terms of BC production effi cacy, the most favorable properties were found in the setting where RMF generator was switched off for the fi rst 72 h of cultivation and switched on for the further 72 h. The results obtained can be used in subsequent studies concerning the optimization of BC production using different types of magnetic fields including RMF, especially.

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Measurement of bacterial adhesion to metal surfaces with different chemical composition - evaluation of different methods

Żywicka A., Fijałkowski K.

Environmental Biotechnology

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2017

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Vol. 13, No. 2

14--22

EN

In the current study attention has been focused on the evaluation of different methods of measurement of bacterial adhesion to the metal surfaces with different chemical composition. The direct methods, which included determination of the number of bacterial cells using fluorescence microscopy and Colony Forming Units (CFU) on agar medium, and indirect methods using Alamar Blue (AB) and MTT assays, were evaluated. The chemical compositions of the metal surfaces included: copper, iron, chromium and nickel. Interaction effects of assay and metal compound have been specifically demonstrated in this study. It was found that metal ions reacted with components of the indirect colorimetric tests used in his study (AB and MTT assay). Consequently, those tests gave positive false results. In contrast to the indirect methods, direct counting methods such as microscopy techniques and CFU counting, were successfully applied for evaluation of bacterial adhesion to the metal surfaces. However, considering the limits for the surfaces of the examined samples for microscopy, the determination of the CFU was found to be the best method for testing the adhesion to metal surfaces. The method, combined with the appropriate detachment procedures allowed for a precise determination of the number of bacteria on the entire surface of the evaluated metal samples.

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Effect of Gluconacetobacter xylinus cultivation conditions on the selected properties of bacterial cellulose

Fijałkowski K., Żywicka A., Drozd R., Kordas M., Rakoczy R.

Polish Journal of Chemical Technology

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2016

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Vol. 18, nr 4

117--123

EN

The aim of the study was to analyze the changes in the parameters of bacterial cultures and bacterial cellulose (BC) synthesized by four reference strains of Gluconacetobacter xylinus during 31-day cultivation in stationary conditions. The study showed that the most visible changes in the analyzed parameters of BC, regardless of the bacterial strain used for their synthesis, were observed in the first 10–14 days of the experiment. It was also revealed, that among parameters showing dependence associated with the particular bacterial strain were the rate and period of BC synthesis, the growth rate of bacteria anchored to the cellulose fibrils, the capacity to absorb water and the water release rate. The results presented in this work may be useful in the selection of optimum culturing conditions and period from the point of view of good efficiency of the cellulose synthesis process.

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Species composition and habitat correlates of amphibian roadkills in different landscapes of southwestern Poland

Orłowski G., Ciesiołkiewicz J., Kaczor M., Radwańska J., Żywicka A.

Polish Journal of Ecology

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2008

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Vol. 56, nr 4

659-671

EN

During four seasons (years 2000-2004) on 52.3 km of roads with traffic frequencies ranging from 350 to 10 500 vehicles day[^-1] and crossing diverse habitats in five regions of south-western Poland 3 742 roadkills from 10 amphibian species were recorded. The most frequent road killed species was common toad Bufo bufo (52% of all roadkills), followed by common frog Rana temporaria (12%), green toad Bufo viridis (11%) and moor frog Rana arvalis (3%). For all surveyed roads the roadkill density was positively correlated with the share of woods and the area of ponds. Actual traffic density was a poor predictor of the number of amphibian roadkills in large landscape scale (all surveyed roads). To assess the factors affecting the number of amphibian roadkills in the small landscape scale the Generalized Linear Models (GLZ) were performed between the number of casualties and five habitat variables (area and number of ponds, share of built-up area, open countryside and woodland) for four circular buffer zones (<200 m, <300 m, <400 m, <500 m) around each of the 100-meter sections within 1.8 km of road crossing an area rich in water bodies. The most important variables in GLZ models were the area and number of ponds. These predictors had statistically significant impact on number of roadkills within buffer zones <500 m (area of ponds) and <400 m (number of ponds).