title: Facilitation of robust growth of Prochlorococcus colonies and dilute liquid cultures by "helper" heterotrophic bacteria.
abstract: Axenic (pure) cultures of marine unicellular cyanobacteria of the Prochlorococcus genus grow efficiently only if the inoculation concentration is large; colonies form on semisolid medium at low efficiencies. In this work, we describe a novel method for growing Prochlorococcus colonies on semisolid agar that improves the level of recovery to approximately 100%. Prochlorococcus grows robustly at low cell concentrations, in liquid or on solid medium, when cocultured with marine heterotrophic bacteria. Once the Prochlorococcus cell concentration surpasses a critical threshold, the "helper" heterotrophs can be eliminated with antibiotics to produce axenic cultures. Our preliminary evidence suggests that one mechanism by which the heterotrophs help Prochlorococcus is the reduction of oxidative stress.
authors.affiliation: Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, USA.
authors.forename: J Jeffrey
authors.initials: JJ
authors.lastname: Morris
authors.forename: Robin
authors.initials: R
authors.lastname: Kirkegaard
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Szul
authors.forename: Zackary I
authors.initials: ZI
authors.lastname: Johnson
authors.forename: Erik R
authors.initials: ER
authors.lastname: Zinser
mesh_terms: D000362:Agar; D020591:Alteromonas / Q000187:drug effects / Q000254:growth & development*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001483:Base Sequence; D018920:Coculture Techniques / Q000379:methods*; D003470:Culture Media; D024881:Drug Resistance, Bacterial; D052836:Heterotrophic Processes; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D048929:Prochlorococcus / Q000254:growth & development*; D012329:RNA, Bacterial / Q000302:isolation & purification; D013307:Streptomycin / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D003470:Culture Media; D012329:RNA, Bacterial; D000362:Agar; D013307:Streptomycin