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

Skórczewski P., Mudryk Z.

Polish Journal of Ecology

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2012

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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.

2

UV Radiation Impact on Enzymatic and Respiratory Activity of Neustonic and Planktonic Bacteria

Walczak M., Burkowska A.

Ecological Chemistry and Engineering. A

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2011

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Vol. 18, nr 5-6

827-833

EN

The surveys were carried out in the pelagic zone of Brzezno lake (the Tuchola Forest). Water samples were collected from the surface microlayer and the subsurface water. The surveys covered respiratory activity of bacteria, using a measurement system OxiTop Control. Also, general activity of hydrolytic enzymes was estimated measuring rates of fluorescein release from fluorescein diacetate. The research was conducted in two experimental layouts: with and without humic substances. Conducted surveys proved substantially lower respiratory and hydrolytic activity of bacteria influenced by UVB radiation compared with bacteria without UVB radiation. The experiments did not prove unambiguous protective operation of HS – only for selected strains with bacteria subjected to UVB radiation in presence of HS demonstrated lower decrease of respiratory and hydrolytic activity.

PL

Badania prowadzono w dwóch układach doświadczalnych: bez substancji humusowych (SH) i w obecności tych substancji. W wyniku przeprowadzonych badań stwierdzono zdecydowanie niższą aktywność oddechow ą i hydrolityczną bakterii po naświetleniu UVB, w porównaniu z bakteriami nie naświetlonymi. Nie stwierdzono jednoznacznie ochronnego działania SH, jedynie w przypadku niektórych szczepów naświetlanie bakterii UVB w obecności SH powodowało mniejszy spadek aktywności oddechowej i hydrolitycznej.

3

Concentrations of heavy metals and bacterial numbers and productivity in surface and subsurface water layers in coastal lake Dolgie Wielkie

Antonowicz J., Mudryk Z., Trojanowski J., Dwulit M.

Ecological Chemistry and Engineering. A

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2008

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Vol. 15, nr 9

873-879

EN

Results of chemical and bacteriological examinations conducted for surface and subsurface water layers of coastal freshwater lake Dolgie Wielkie were presented. The obtained data indicated that there were substantial differences in concentrations of heavy metals, abundance and productivity of bacteria in the water layers studied. It was found that the highest concentration of heavy metals and the lowest counts of total and heterotrophic bacteria were recorded in the film layer. However, a higher level of secondary production than in neustonic bacteria was found for planktonic bacteria. The results justify a conclusion that heavy metals accumulated in the surface layers may have a significant inhibitory effect on counts and productivity of neustonic bacteria.

PL

Przedstawiono wyniki chemicznych i bakteriologicznych badań powierzchniowych i podpowierzchniowych warstw wody przymorskiego słodkowodnego jeziora Dołgie Wielkie. Uzyskane wyniki wykazały istotne różnice w stężeniu metali ciężkich, liczebności oraz poziomie produkcji bakterii w badanych warstwach wody. Wykazano, że największe stężenie metali ciężkich, najmniejsza ogólna liczebność bakterii oraz liczebność bakterii heterotroficznych notowane było w filmie powierzchniowym. Jednakże wyższy poziom wtórnej produkcji obserwowano u bakterii planktonowych niż neustonowych. Uzyskane wyniki upoważniają do stwierdzenia, że metale ciężkie zakumulowane w powierzchniowych warstwach wody mogą mieć istotny inhibitorowy wpływ na liczebność i produktywność bakterii neustonowych.

4

Enzymatic activity and degradation of organic macromolecules by neustonic and planktonic bacteria in an estuarine lake

Mudryk Zbigniew Jan, Skórczewski Piotr

Polish Journal of Ecology

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2006

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Vol. 54, nr 1

3-14

EN

Neustonic (film layer -90 [mi]m, surface layer - 240 [mi]m) and planktonic bacteria (subsurface layer - 10-15 cm) participating in the processes of decomposition of organic macromolecular compounds, and their potential capability to synthesise extracellular enzymes were studied in a shallow estuarine lake (Lake Gardno - Baltic coast). The studied bacteria were capable of decomposing a wide spectrum of organic macromolecular compounds. Most bacteria inhabiting surface and subsurface water layers hydrolysed lipids, proteins and DNA. The microflora hydrolysing cellulose was represented by the least abundant group of organisms. Of the studied enzymes, alkaline and acid phosphatases, leucine arylaminase, esterase, and esterase lipase were synthesised most actively while [Beta]-glucouronidase ([Beta]Gl) and a-fucosidase ([alfa]Fu) were synthesized least actively. It can be clearly seen that enzymatic activity was stratified, and there were differences between studied water layers. Bacterial strains isolated from surface and subsurface layers were more active in synthesizing extracellular enzymes than bacteria inhabiting the film layer. Bacteria isolated from various parts of Lake Gardno synthesized the tested hydrolytic enzymes with a similar intensity.

5

Neustonic versus planktonic bacteria in eutrophic lake

Kalwasińska A., Donderski W.

Polish Journal of Ecology

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2005

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Vol. 53, nr 4

571-577

EN

This paper presents the results of research on the number, the rate of secondary production and physiological properties of neustonic (surface microlayer SM ≈ 250 μm) and planktonic (subsurface water SSW ≈ 10-15cm) bacteria of the eutrophic lake (TP 30-99 μg l-1; TN 0.94-1.76 mg l-1; chlorophyll a 26.4-56.9 mg l-1; water transparency 1.2-1.9 m). It was found that the total number of neustonic bacteria (TNB) varied from 1.28 × 106 to 1.98 × 106 cells ml-1 and was from 1.4 to 2.0 times higher than the number of planktonic bacteria (P <0.001). TNB range for planktonic bacteria oscillated between 0.75 × 106 and 1.45 × 106 cells ml-1. The number of heterotrophic neustonic (SM) bacteria (CFU 22°C) was also higher by 2.0 to 13.3 times (P <0.001) being between 1.48 and 12.5 × 103 cells ml-1 while the CFU of bacteria in the SSW oscillated between 0.35 to 0.94 × 103 cells ml-1. Both the values of TNB and CFU displayed a distinct seasonal variation (P <0.001). However, the rate of secondary production of planktonic bacteria was higher (from 1.1 to 6.0 times) than the rate of production of neustonic bacteria (P <0.05) and displayed seasonal variability (P <0.001). The rate of secondary production in subsurface water ranged from 0.676 to 1.265 μgC l-1 h-1 while in surface microlayer from 0.118 to 0.597 μgC l-1 h-1. In neuston the bacteria decomposing fat and DNA were more common than in plankton (P <0.05).

6

Interaction of estuarine bacterioneuston and bacterioplankton with elevated mercury concentrations

Mudryk Z. J., Dwulit M.

Polish Journal of Ecology

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2004

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Vol. 52, nr 3

301-310

EN

The effect of different concentrations of mercury on the number and respiratory activity of neustonic and planktonic bacteria derived from estuarine Lake Gardno (Baltic Coast, Poland) was studied. The laboratory experiments demonstrated that mercuric ions (Hg^2+) exhibited toxic effects on abundance and oxygen uptake of neustonic and planktonic bacteria. Bacterioneuston and bacterioplankton showed different responses to the mercuric ions. The neustonic bacteria showed higher levels of tolerance to various concentrations of Hg (10-15 mg dm^-3) in the culture medium than the planktonic ones (<10 mg dm^-3). It was found out that the bacteria isolated from freshwater zone of Lake Gardno were more tolerant to the increasing concentration of mercury ions (10-20 mg dm^-3) than bacteria isolated from the seawater and mixed zones of lakes. Non-pigmented bacteria from all layers and zones were more tolerant to the higher Hg^2+ concentrations than pigmented ones. High concentrations (above 8 [mi]g cm^-3) of mercury chloride in the respiratory substrate blocked completely oxygen uptake by neustonic and planktonic bacteria.

7

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

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

Oceanological Studies

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2000

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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.

8

Occurrence and distribution of bacteria decomposing organic phosphorus compounds in the surface seawater layers

Mudryk Z.

Oceanological Studies

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1998

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Vol. 27, No. 3

45-55

EN

The ability of neustonic and planktonic bacteria inhabiting the Gdańsk Deep to decompose organie forms of phosphorus was studied. It was found that bacteria hydrolysed phytin and DNA most actively, while only smali percentage of bacterial strains studied was able to depolymerize glycero-phosphate. Significant differences in the intensity of minerahzation of organie phosphorus compounds between ncustonic and planktonic bacteria were observed. This process was characterised by consid-erable diel fluctuations. It was also found that in the microlayer, the activity of alkaline phosphatase was higher than of acid phosphatase.