Wyniki wyszukiwania - Biblioteka Nauki

1

The occurrence of lipolytic bacteria and the activity of extracellular lipases in a riverine ecosystem

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Skórczewski P. , Mudryk Z.

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2009

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tom Vol. 38, No.4

89-101

EN

This study determined the numbers and distribution of heterotophic and lipolytic bacteria and the activity of lipases in the water of the Słupia River, in the section of the river that flows through the city of Słupsk. From spring to fall the mean number of heterotrophic bacteria remained at a relatively constant level (158.3 × 103 cells cm^-3 – 169.4 × 103 cells cm^-3), whereas in winter a sudden drop to only 18.3 × 103 cells cm^-3 was found. The numbers of heterotrophic bacteria in the whole studied section of the river were similar. The mean number of lipolytic bacteria reached a maximum in spring (12.9 × 103 cells cm^-3), was high in summer (10.5 × 103 cells cm^-3), and reached a minimum (1.3 × 103 cells cm^-3) in winter. Lipolytic bacteria accounted for only 5 to 8% of the total number of heterotrophic bacteria. No marked differences in the numbers of lipolytic bacteria were determined within the section of the river studied. The highest levels of lipase activity were determined in spring (18.9 nM MUF dm^-3 h^-1) and fall (19.9 nM MUF dm-3 h-1), while the lowest (11.0 nM MUF dm^-3 h^-1) were noted in winter. There were no differences in the level of activity of lipolytic enzymes among the sites studied.

2

Different antibiotic resistance of neustonic and planktonic bacteria in a freshwater coastal lake : implication for strain selection

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Skórczewski P. , Mudryk Z.

Polish Journal of Ecology

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2012

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tom Vol. 60, nr 1

153-162

EN

Antibiotic resistance of bacteria was observed in various aquatic environments including seas, rivers, lakes, coastal areas, surface water and sediments. The increased implementation of antibiotics into these environments through medical therapy, agriculture and animal husbandry has resulted in new selective pressures on natural bacterial aquatic populations. Antibiotic resistance of heterotrophic bacteria isolated from the surface microlayer and subsurface water of freshwater coastal polymictic and low-productive lake was studied. Antibiotic resistance was determined by the single disc diffusion method. The resistance level of bacteria to various antibiotics differed considerably. Bacteria were most resistant to ampicillin, ciprofloxacin, clindamycin, erythromycin and penicillin. Majority of bacterial strains showed resistance to 4.6 out of 18 antibiotics tested. As a rule, neustonic bacteria (antibiotic resistance index, ARI 0.44) were more resistant to the studied antibiotics than planktonic bacteria (ARI 0.32). 70-90% of neustonic bacteria were resistant to ampicillin, clindamycin and erythromycin, 60-70% of planktonic bacteria were resistant to ampicillin, ciprofloxacin and penicillin. Differences between pigmented and non-pigmented bacteria in their resistance to the tested antibiotics were observed. Above 40% of achromogenic bacterial strains were resistant to ampicillin, clindamycin and penicillin. Among bacterial strains characterised by their ability to synthesize carotenoids, more than 30% was resistant to ampicillin and ciprofloxacin. Bacterial resistance level to antibiotics depended on their chemical structure. Bacteria isolated from study lake were most resistant to quinolones and lincosamides while they were most susceptible to tetracyclines and aminoglycosides. Results presented in this paper indicate that antibiotics are a significant selection factor and probably play an important role in regulating the composition of bacterial communities in aquatic ecosystems. Adaptive responses of bacterial communities to several antibiotics observed in the present study may have possible implications for the public health.

3

Abundance and production of bacteria in a marine beach (Southern Baltic Sea)

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Podgórska B. , Mudryk Z. , Skórczewski P.

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tom Vol. 56, nr 3

405-414

EN

The paper presents the results of the study of abundance, biomass, mean cell volume and secondary production of bacteria inhabiting a marine-bay sandy beach, at southern Baltic Sea coast (Sopot) in summer season. The differences of bacteriological parameters among sites across beach horizontal profile were determined. Maximal value of the total bacteria numbers (8.59 [plus or minus] 0.73 x 10[^7]cells g[^-1] dw), biomass (15.2 [plus or minus] 4.4 [my]g C g[^-1] dw) and cell volume of bacterium (0.056 [plus or minus] 0.011 [my]m3) was noted at the waterline and bacterial secondary production was highest in the dune (172.3 [plus or minus] 86.6 [my]g C g[^-1] dw d[^-1]) and at the waterline (119.9 [plus or minus] 40.5 [my]g C g[^-1] dw d[^-1]). Marked differences in the level of bacteriological parameters between surface and subsurface sand layers were estimated. In the sea, at the waterline and in the middle of the beach higher numbers of bacteria, their biomass and secondary production were found in the surface (0.1 cm) than in the subsurface (5.10 cm) sand layers. A reverse situation was observed in the dune.

4

Effect of some heavy metals on neustonic and planktonic bacteria isolated from the Deep of Gdańsk

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Mudryk Z. , Donderski W. , Skórczewski P. , Walczak M.

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tom Vol. 29, No. 1

89-99

EN

The effect of different concentrations of heavy metal ions Hg+2, Cd+2, Zn+2, Cu+2 on growth and respiratory activity of neustonic and planktonic bacteria derived from the Deep of Gdańsk was studied. The laboratory experiments demonstrated that all heavy metals examined exhibited toxic effects on the development and oxygen uptake by neustonic and planktonic bacteria. This effect depended on the kind of the metal and its concentration.

5

Occurrence of potentially human pathogenic bacteria in the seawater and in the sand of the recreational coastal beach in the southern Baltic Sea

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Mudryk Z. J. , Gackowska J. , Skórczewski P. , Perliński P. , Zdanowicz M.

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2014

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tom Vol. 43, No. 4

366--373

EN

The occurrence and the distribution of potentially human pathogenic bacteria such as Aeromonas, Pseudomonas aeruoginosa, Staphylococcus and Vibrio-like organisms in the sand and the adjacent seawater of the recreational coastal beach were studied. The highest mean number among these four studied groups of bacteria was represented by Aeromonas-like organisms and the lowest one by Staphylococcus-like organisms. Dry sand was inhabited by the highest number of all studied potentially pathogenic bacteria. Within a year, the number of the studied bacteria inhabiting the sand and the seawater showed considerable monthly changes. There were differences in the abundance of potentially pathogenic bacteria between the surface and the subsurface sand layers with a clear decrease in their number toward the deeper layers of the sand.