Microcystis spp. is a cyanobacterial species that commonly forms blooms in euthrophic lakes and grows in colonial forms. There are environmental, ecological and health concerns regarding the expansion of these bio-formations, since they determine water quality deterioration, generate anoxia and alter existing food webs. In addition, toxin secondary metabolites pose serious hazards for humans and livestock [1]. Cell aggregation is possible thanks to microbial-produced exopolysaccharides (EPS), produced mainly by Microcystis and other bloom-associated cyanobacteria that embed Microcystis cells within the bloom colony. During extensive blooming, EPS may be produced in large amounts, that in one case were reckoned to occupy 0.0001-0.007 % of an eutrophic lake water volume in the epilimnion [2]. Beside their structural role, EPS represent a huge carbon input available to bacterial heterotrophic population during water-blooming. By these means, the study of EPS degradation is very important to describe C cycle within the community. At the same time, the individuation of those bacterial species in the community that are more able to degrade EPS could lead to optimize new biotechnological approaches to control water-bloom spread. In this work, Microcystis biomass was harvested from the surface layer of lake Kinneret (Sea of Galilee, Israel) and isolation procedures were performed to obtain axenic cultures of Microcystis-associated heterotrophic bacteria. By using Biolog carbon substrate utilization approach, the growth of 4 different bacterial strains was tested on cyanobacterial EPS alone, and combined to 8 different carbon sources (namely pyruvate, gluconate, ribose, glucose, galactose, xylose, glutamic acid and yeast extract). Results showed that some of the used carbon sources stimulated the growth on cyanobacterial EPS, the most relevant being glutamic acid, which produced a relevant growth of one of the strains
Microbial-degradation of cyanobacterial-produced exopolysaccharides in Microcystis bloom formations in an Israeli eutrophic lake
ROSSI, FEDERICO
Primo
;
2015-01-01
Abstract
Microcystis spp. is a cyanobacterial species that commonly forms blooms in euthrophic lakes and grows in colonial forms. There are environmental, ecological and health concerns regarding the expansion of these bio-formations, since they determine water quality deterioration, generate anoxia and alter existing food webs. In addition, toxin secondary metabolites pose serious hazards for humans and livestock [1]. Cell aggregation is possible thanks to microbial-produced exopolysaccharides (EPS), produced mainly by Microcystis and other bloom-associated cyanobacteria that embed Microcystis cells within the bloom colony. During extensive blooming, EPS may be produced in large amounts, that in one case were reckoned to occupy 0.0001-0.007 % of an eutrophic lake water volume in the epilimnion [2]. Beside their structural role, EPS represent a huge carbon input available to bacterial heterotrophic population during water-blooming. By these means, the study of EPS degradation is very important to describe C cycle within the community. At the same time, the individuation of those bacterial species in the community that are more able to degrade EPS could lead to optimize new biotechnological approaches to control water-bloom spread. In this work, Microcystis biomass was harvested from the surface layer of lake Kinneret (Sea of Galilee, Israel) and isolation procedures were performed to obtain axenic cultures of Microcystis-associated heterotrophic bacteria. By using Biolog carbon substrate utilization approach, the growth of 4 different bacterial strains was tested on cyanobacterial EPS alone, and combined to 8 different carbon sources (namely pyruvate, gluconate, ribose, glucose, galactose, xylose, glutamic acid and yeast extract). Results showed that some of the used carbon sources stimulated the growth on cyanobacterial EPS, the most relevant being glutamic acid, which produced a relevant growth of one of the strainsI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
