title: Resistance of marine bacterioneuston to solar radiation.
abstract: A total of 90 bacterial strains were isolated from the sea surface microlayer (i.e., bacterioneuston) and underlying waters (i.e., bacterioplankton) from two sites of the northwestern Mediterranean Sea. The strains were identified by sequence analysis, and growth recovery was investigated after exposure to simulated solar radiation. Bacterioneuston and bacterioplankton isolates were subjected to six different exposure times, ranging from 0.5 to 7 h of simulated noontime solar radiation. Following exposure, the growth of each isolate was monitored, and different classes of resistance were determined according to the growth pattern. Large interspecific differences among the 90 marine isolates were observed. Medium and highly resistant strains accounted for 41% and 22% of the isolates, respectively, and only 16% were sensitive strains. Resistance to solar radiation was equally distributed within the bacterioneuston and bacterioplankton. Relative contributions to the highly resistant class were 43% for gamma-proteobacteria and 14% and 8% for alpha-proteobacteria and the Cytophaga/Flavobacterium/Bacteroides (CFB) group, respectively. Within the gamma-proteobacteria, the Pseudoalteromonas and Alteromonas genera appeared to be highly resistant to solar radiation. The majority of the CFB group (76%) had medium resistance. Our study further provides evidence that pigmented bacteria are not more resistant to solar radiation than nonpigmented bacteria.
authors.affiliation: Observatoire Océanologique, Université Pierre et Marie Curie, UMR 7621-INSU-CNRS, BP44, 66651 Banyuls-sur-Mer, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Agogué
authors.forename: Fabien
authors.initials: F
authors.lastname: Joux
authors.forename: Ingrid
authors.initials: I
authors.lastname: Obernosterer
authors.forename: Philippe
authors.initials: P
authors.lastname: Lebaron
mesh_terms: D004269:DNA, Bacterial / Q000032:analysis; D004275:DNA, Ribosomal / Q000032:analysis; D006090:Gram-Negative Bacteria / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification / Q000528:radiation effects*; D008969:Molecular Sequence Data; D010933:Plankton / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification / Q000528:radiation effects; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D011836:Radiation Tolerance; D012623:Seawater / Q000382:microbiology; D017422:Sequence Analysis, DNA; D013472:Sunlight
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S