Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 42

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 3 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 3 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
This study examined biodegradation of the insecticide deltamethrin (1 µg dm⁻³) by homogenous cultures of planktonic (n = 25) and benthic (n = 25) bacteria as well as by heterogenous cultures (n = 1) containing a mixture of 25 bacterial strains. The bacteria were collected from subsurface water layer (25 cm below the surface) and a surface layer of bottom sediments (down to 10–15 cm) of eutrophic lake Chełmżyńskie. Results indicate that planktonic bacteria were characterized by higher average ability to biodegrade deltamethrin than benthic bacteria (p < 0.05). After 15-day incubation, bacteria isolated from subsurface water reduced the initial concentration of deltamethrin by 69%, while the average effectiveness of benthic bacteria equaled 23%. The level of deltamethrin biodegradation in mixed cultures of benthic and planktonic bacteria after 5, 10, and 15 days of incubation was higher than that in homogenous cultures. It was demonstrated that microorganisms from the Sphingomonas paucimobilis species and the Moraxella genus, among planktonic bacteria, as well as Burkholderia cepacia and Bacillus mycoides species, among benthic bacteria, were the most effective in reducing the concentration of this insecticide.
This study evaluates the biodegradation of carbendazim (1 mg/l) by homogeneous cultures of planktonic (N=25) and benthic (N=25) bacteria as well as by heterogeneous cultures (N=1) containing a mixture of 25 bacterial strains. The bacteria were collected from a 25 cm subsurface water layer and a 5-10 cm surface layer of bottom sediments of lake Chełmżyńskie. Results indicate that bacterioplankton are better able to decompose carbendazim than benthic bacteria (p<0.05). In the case of decomposition by planktonic bacteria, the mean half-life of carbendazim equaled 40 days. Benthic bacteria, on average, required 60 days to reduce the concentration of fungicide by 37%. The level of biodegradation of carbendazim in mixed cultures of benthic and planktonic bacteria after a 20-day incubation period was lower than the average value of its biodegradation in homogeneous cultures. Forty- and 60-day homogeneous cultures of planktonic bacteria were characterized by a higher mean level of carbendazim biodegradation than that of the mixed culture. Decomposition of the fungicide in 40- and 60-day mixed cultures of benthic bacteria was higher than the mean value of biodegradation of this compound in homogeneous cultures. We demonstrated that among planktonic bacteria, the species Sphingomonas paucimobilis, Aeromonas hydrophila, and Pseudomonas fluorescens were the most efficient in reducing the concentration of carbendazim, while among benthic bacteria, Burkholderia cepacia and two unidentified strains of bacillus were the most efficient.
The paper presents a study on biodegradation of carbendazim (1 mg/l) by homogeneous cultures of epiphytic (n = 25) and neustonic (n = 25) bacteria and heterogeneous (n= 1) cultures containing a mixture of 25 bacterial strains isolated from epidermis of the Common Reed (Phragmites australis, (Cav.) Trin. ex Steud.) and surface microlayer (SM ≈ 250 μm) of eutrophic lake Chelmzynskie. Results indicate that epiphytic bacteria are characterized by higher average capacity to decompose carbendazim than neustonic bacteria (p<0.05). The half-life of carbendazim in epiphytic bacterial cultures equaled an average of 60 days. In the same period, neustonic bacteria reduced the concentration of the fungicide by 31 %. The level of carbendazim biodegradation in mixed cultures of epiphytic and neustonic bacteria after 20-day incubation was lower than the biodegradation level in homogeneous cultures. Sixty-day homogeneous cultures of epiphytic and neustonic bacteria were characterized by a higher mean level of carbendazim biodegradation than mixed cultures. After 40-day incubation, mean values of biodegradation of the fungicide in homogeneous and mixed cultures were similar. It was demonstrated that among epiphytic bacteria, Pseutlomonas luteola was the most efficient organism in reducing the concentration of carbendazim. Among neustonic bacteria, Burkholderia cepacia and Aeromonas hydrophila were the most effective in degradation of the fungicide.
A new enzymatic activity, which catalyses formation in vitro of di-O-(indole-3-acetyl)-D-glucose from 1-O-(indole-3-acetyl)-beta-D-glucose has been found in extracts of Zea mays seedlings. The structure of di-O-(indole-3-acetyl)-D-glucose, not as yet described, has been assigned by GC-MS, 1H NMR and ammonolysis.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 3 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.