Y V Alexeeva

Publications (7)12.31 Total impact

• Article: Impact of cultivation conditions on haemolytic activity of Pseudoalteromonas issachenkonii KMM 3549T.

  Y V Alexeeva, N I Kalinovskaya, T A Kuznetsova, E P Ivanova
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  ABSTRACT: The present work aimed to study the effects of cultivation conditions on the haemolytic activities of Pseudoalteromonas issachenkonii. The kinetics of growth and haemolytic activities was investigated on sea-salts and NaCl-based nutrient media supplemented with either starch, or KBr over a period of 140 h. The first haemolytic activity occurred when bacterial cells reached the late stationary phase. The second haemolytic activity was observed in marine broth (MB) after 110 h of incubation. Addition of Fe to the culture medium neither affected bacterial growth nor reduced the haemolytic activity. However, the activity was enhanced in the presence of iron chelator. The second haemolytic activity was not affected by Ca2+, or inhibited by chymotrypsin or EDTA. The production of haemolysins by P. issachenkonii was greater on MB and was dependent on both the medium composition and time of incubation. The second haemolytic activity was heat stable, nonproteinaceous, calcium-independent and was regulated by Fe. The results demonstrated the importance of optimization of both the media composition and monitoring the haemolytic activity over a prolonged cultivation time to detect different types of haemolysins.
  Letters in Applied Microbiology 02/2004; 38(1):38-42. · 1.62 Impact Factor
• Article: Impact of cultivation conditions on haemolytic activity of Pseudoalteromonas issachenkonii KMM 3549T

  Y.V. Alexeeva, N.I. Kalinovskaya, T.A. Kuznetsova, E.P. Ivanova
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  ABSTRACT: Aims:  The present work aimed to study the effects of cultivation conditions on the haemolytic activities of Pseudoalteromonas issachenkonii.Methods and Results:  The kinetics of growth and haemolytic activities was investigated on sea-salts and NaCl-based nutrient media supplemented with either starch, or KBr over a period of 140 h. The first haemolytic activity occurred when bacterial cells reached the late stationary phase. The second haemolytic activity was observed in marine broth (MB) after 110 h of incubation. Addition of Fe to the culture medium neither affected bacterial growth nor reduced the haemolytic activity. However, the activity was enhanced in the presence of iron chelator. The second haemolytic activity was not affected by Ca2+, or inhibited by chymotrypsin or EDTA.Conclusions:  The production of haemolysins by P. issachenkonii was greater on MB and was dependent on both the medium composition and time of incubation. The second haemolytic activity was heat stable, nonproteinaceous, calcium-independent and was regulated by Fe.Significance and Impact of the Study:  The results demonstrated the importance of optimization of both the media composition and monitoring the haemolytic activity over a prolonged cultivation time to detect different types of haemolysins.
  Letters in Applied Microbiology 12/2003; 38(1):38 - 42. · 1.62 Impact Factor
• Article: Optimization of glycosidases production by Pseudoalteromonas issachenkonii KMM 3549T

  Y.V. Alexeeva, E. P. Ivanova, I.Y. Bakunina, T.N. Zvaygintseva, V.V. Mikhailov
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  ABSTRACT: Aims: The present work aimed to design an optimized medium to yield a higher production of glycosides by Pseudoalteromonas issachenkonii KMM 3549T. Methods and Results: Higher levels of fucoidan hydrolase, alginase, laminaranase and b-N-acetylglucosaminidase production were obtained with peptone concentrations ranging from 2·5 g l−1 to 10 g l−1, while the presence of both yeast extract and glucose did not affect enzyme production. The activity of fucoidan hydrolase and laminaranase increased up to 4·83 µM h−1 mg−1 and 19·23 µM h−1 mg−1 protein, respectively, in growth media containing xylose (1·0 g l−1), laminarin (0·5 g l−1) or alginate (0·5 g l−1), and production of b-N-acetylglucosaminidase substantially increased in the presence of fucoidan (0·5 g l−1) or galactose (1 g l−1). All polysaccharides tested in concentrations of 0·5 g l−1 fucoidan and 0·2 g l−1 fucose induced production of alginase (up to 5·06 µM h−1 mg−1 protein). Conclusions: The production of glycosidases is not only stimulated by the presence of algal polysaccharides, but may also be stimulated by monosaccharides (e.g. xylose). Significance and Impact of the Study: The production of glycosidases by Pseudoalteromonas issachenkonii KMM 3549T was significantly improved by using a simple nutrient medium containing peptone (2·5 g l−1) and xylose (5·0 g l−1) in 100% natural seawater.
  Letters in Applied Microbiology 09/2002; 35(4):343 - 346. · 1.62 Impact Factor
• Source

  Available from: Elena P. Ivanova

  Article: Two species of culturable bacteria associated with degradation of brown algae Fucus evanescens.

  E P Ivanova, I Yu Bakunina, T Sawabe, K Hayashi, Y V Alexeeva, N V Zhukova, D V Nicolau, T N Zvaygintseva, V V Mikhailov
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  ABSTRACT: The heterotrophic microbial enrichment community established during degradation of brown algae Fucus evanescens was characterized. A two-species bacterial community of marine culturable gamma-proteobacteria consisted of Pseudoalteromonas and Halomonas. The first member of the community, Pseudoalteromonas sp., was highly metabolically active, had bacteriolytic and hemolytic activities, produced proteinases (gelatinase and caseinase), lipases, DNases, and fucoidanhydrolases, laminaranases, alginases, pustulanases, beta-glucosidases, beta-galactosidases, beta-N-acetylglucosaminidases, and beta-xylosidases. The second member of the community, Halomonas marina, produced only caseinase and DNase, and it did not hydrolyze algal polysaccharides. Both members of the studied bacterial community utilized a range of easily assimilable monosaccharides and other low molecular weight organic substances. The results provide an evidence of the complex metabolic interrelations between two members of this culturable community. One of them Pseudoalteromonas sp., most likely plays the major role in the initial stages of algal degradation; the other one, H. marina, resistant to the bacteriolytic activity of the former, is able to utilize the products of degradation of polysaccharides.
  Microbial Ecology 04/2002; 43(2):242-9. · 2.91 Impact Factor
• Source

  Available from: Elena P. Ivanova

  Article: Optimization of glycosidases production by Pseudoalteromonas issachenkonii KMM 3549(T).

  Y V Alexeeva, E P Ivanova, I Y Bakunina, T N Zvaygintseva, V V Mikhailov
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  ABSTRACT: The present work aimed to design an optimized medium to yield a higher production of glycosides by Pseudoalteromonas issachenkonii KMM 3549(T). Higher levels of fucoidan hydrolase, alginase, laminaranase and b-N-acetylglucosaminidase production were obtained with peptone concentrations ranging from 2.5 g l(-1) to 10 g l(-1), while the presence of both yeast extract and glucose did not affect enzyme production. The activity of fucoidan hydrolase and laminaranase increased up to 4.83 microM h(-1) mg(-1) and 19.23 microM h(-1) mg(-1) protein, respectively, in growth media containing xylose (1.0 g l(-1)), laminarin (0.5 g l(-1)) or alginate (0.5 g l(-1)), and production of b-N-acetylglucosaminidase substantially increased in the presence of fucoidan (0.5 g l(-1)) or galactose (1 g l(-1)). All polysaccharides tested in concentrations of 0.5 g l(-1) fucoidan and 0.2 g l(-1) fucose induced production of alginase (up to 5.06 microM h(-1) mg-1 protein). The production of glycosidases is not only stimulated by the presence of algal polysaccharides, but may also be stimulated by monosaccharides (e.g. xylose). The production of glycosidases by Pseudoalteromonas issachenkonii KMM 3549(T) was significantly improved by using a simple nutrient medium containing peptone (2.5 g l(-1)) and xylose (5.0 g l(-1)) in 100% natural seawater.
  Letters in Applied Microbiology 02/2002; 35(4):343-6. · 1.62 Impact Factor
• Article: Two Species of Culturable Bacteria Associated With Degradation of Brown Algae Fucus Evanescens

  E.P. Ivanova, I.Yu. Bakunina, T. Sawabe, K. Hayashi, Y.V. Alexeeva, N.V. Zhukova, D.V. Nicolau, T.N. Zvaygintseva, V.V. Mikhailov
  Microbial Ecology 01/2002; 43(2):242-249. · 2.91 Impact Factor
• Article: Characterization of unusual alkaliphilic gram-positive bacteria isolated from degraded brown alga thalluses.

  E P Ivanova, J P Wright, A M Lysenko, N V Zhukova, Y V Alexeeva, V Buljan, N I Kalinovskaya, D V Nicolau, R Christen, V V Mikhailov
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  ABSTRACT: Two orange-pigmented Gram-positive, aerobic bacteria were isolated from enrichment culture during degradation of brown alga Fucus evanescens thalluses. In this work, atomic force microscopy (AFM) has been used to study the cell morphology. The non-contact mode imaging revealed unusual irregular coccoid shape of cells, possessing a single flagellum. Bacteria produced carotenoid pigments, were chemo-organotrophic, alkaliphilic and halo-tolerant growing well on nutrient media containing up to 15% NaCl. Growth temperature ranged from 5 to 45 degrees C. The DNA base compositions were 48 mol% G + C and the level of DNA similarity of two strains was conspecific (98%). A comparative phylogenetic analysis of 16S rRNA gene sequences revealed that the strain KMM 3738 tightly clustered with recently described Planococcus maritimus (99.9% 16S rRNA gene sequence similarity). DNA-DNA hybridisation experiments revealed that DNA from the KMM 3738 showed 12-15% and 16-35% of genetic relatedness with the DNA of type strains of the genera Planomicrobium and Planococcus, respectively, and 87% with DNA from Planococcus maritimus, indicating that new isolates belong to the later species.
  Mikrobiolohichnyĭ zhurnal (Kiev, Ukraine: 1993) 68(4):10-20.