| Abstract | Transparent exopolymer particles (TEP) are mainly acidic polysaccharides directly or indirectly formed by phytoplankton and bacteria. These particles are often colonized by picoplankton and considered a hot spot for microbial activity. Recent studies suggested an important role of Synechococcus in TEP production found in lakes and prompted us to further investigate this issue using monoclonal xenic cultures of Synechococcus. We tested TEP production under oxidative stress in two treatments, one with hydrogen peroxide and another treated with ultraviolet radiation (UVR) and high photosynthetic active radiation (PAR), compared with an unstressed control. Our results showed a cell-normalized TEP production, ranging from 12 to 238 ng C cell among strains, not only under stress but also in the control with non-limiting nutrients. Our data prove that freshwater communities of Synechococcus and their associated het-erotrophic microflora, are capable of producing TEP even during growth phase. The oxidative stress induced extra production of TEP up to 400 ng C cell in one of our phycocyanin-type (PC) strain. The phycoerythrin-type (PE) strains increased TEP production, particularly under UV-PAR stress, whereas the PC strains did it under HO stress. This study provides new perspectives on the potential role of freshwater Synechococcus in TEP production. se only. |
| Text | 420913 2019 10.4081/jlimnol.2019.1907 Scopus 2 s2.0 85077678717 Cyanobacteria Synechococcus Transparten exopolymeric substances UV Tep production under oxidative stress of the picocyanobacterium Synechococcus Callieri C.; Sathicq M.B.; Cabello Yeves P.J.; Eckert E.M.; Hernandez Aviles J.S. Microbial Ecology Group, CNR IRSA Water Research Institute, Verbania, Microbial Ecology Group, CNR IRSA Water Research Institute, Verbania, Italy, , Italy; Institute of Limnology Dr. Raul A. Ringuelet , National University of La Plata National Scientific and Technical Research Council UNLP CONICET , La Plata, Institute of Limnology Dr. Raul A. Ringuelet , National University of La Plata National Scientific and Technical Research Council UNLP CONICET , La Plata, Argentina, , , Argentina; Institute of Limnology Dr. Raul A. Ringuelet , National University of La Plata National Scientific and Technical Research Council UNLP CONICET , La Plata, Institute of Limnology Dr. Raul A. Ringuelet , National University of La Plata National Scientific and Technical Research Council UNLP CONICET , La Plata, Argentina, , , Argentina; Evolutionary Genomics Group, Plant Science and Microbiology Department, Miguel Hernandez University, San Juan de Alicante, Evolutionary Genomics Group, Plant Science and Microbiology Department, Miguel Hernandez University, San Juan de Alicante, Spain, , Spain; Laboratory of Limnology, UMIEZ, Biology Department, National Autonomous University of Mexico UNAM , Mexico City, Laboratory of Limnology, UMIEZ, Biology Department, National Autonomous University of Mexico UNAM , Mexico City, Mexico, , Mexico Transparent exopolymer particles TEP are mainly acidic polysaccharides directly or indirectly formed by phytoplankton and bacteria. These particles are often colonized by picoplankton and considered a hot spot for microbial activity. Recent studies suggested an important role of Synechococcus in TEP production found in lakes and prompted us to further investigate this issue using monoclonal xenic cultures of Synechococcus. We tested TEP production under oxidative stress in two treatments, one with hydrogen peroxide and another treated with ultraviolet radiation UVR and high photosynthetic active radiation PAR , compared with an unstressed control. Our results showed a cell normalized TEP production, ranging from 12 to 238 ng C cell among strains, not only under stress but also in the control with non limiting nutrients. Our data prove that freshwater communities of Synechococcus and their associated het erotrophic microflora, are capable of producing TEP even during growth phase. The oxidative stress induced extra production of TEP up to 400 ng C cell in one of our phycocyanin type PC strain. The phycoerythrin type PE strains increased TEP production, particularly under UV PAR stress, whereas the PC strains did it under HO stress. This study provides new perspectives on the potential role of freshwater Synechococcus in TEP production. se only. 78 Published version http //www.scopus.com/record/display.url eid=2 s2.0 85077678717 origin=inward Articolo in rivista Istituto per lo Studio degli Ecosistemi. 1129 5767 Journal of limnology Testo stamp. Journal of limnology Testo stamp. J. limnol. Testo stamp. Journal of limnology. Testo stamp. SATHICQ MARIA BELEN cristiana.callieri CALLIERI CRISTIANA estermaria.eckert ECKERT ESTER MARIA |
