title: Discovery of bacterial polyhydroxyalkanoate synthase (PhaC)-encoding genes from seasonal Baltic Sea ice and cold estuarine waters.
abstract: Polyhydroxyalkanoates (PHAs) are macromolecules produced by bacteria as means for storing carbon and energy in intracellular granules. PHAs have physical properties similar to those of plastics and have become of interest to industry as materials for environmentally friendly bioplastic production. There is an ongoing search for new PHA-producing bacterial strains and PHA-synthesizing enzymes tolerating extreme conditions to find ways of producing PHAs at cold temperatures and high solute concentrations. Moreover, the study of PHA producers in the sea-ice biome can aid in understanding the microbial ecology of carbon cycling in ice-associated ecosystems. In this study, PHA producers and PHA synthase genes were examined under the extreme environmental conditions of sea ice and cold seawater to find evidence of PHA production in an environment requiring adaptation to high salinity and cold temperatures. Sea ice and cold estuarine water samples were collected from the northern Baltic Sea and evidence of PHA production was gathered, using microscopy with Nile Blue A staining of PHA-granules and PCR assays detecting PHA-synthesis genes. The PHA granules and PHA synthases were found at all sampling locations, in both sea ice and water, and throughout the sampling period spanning over 10 years. Our study shows, for the first time, that PHA synthesis occurs in Baltic Sea cold-adapted bacteria in their natural environment, which makes the Baltic Sea and its cold environments an interesting choice in the quest for PHA-synthesizing bacteria and synthesis genes.
authors.affiliation: Division of Microbiology and Biotechnology, Department of Food and Environmental Sciences, University of Helsinki, P.O. box 56, Biocenter 1, 00014, Helsinki, Finland, katariina.parnanen@helsinki.fi.
authors.forename: Katariina
authors.initials: K
authors.lastname: Pärnänen
authors.forename: Antti
authors.initials: A
authors.lastname: Karkman
authors.forename: Marko
authors.initials: M
authors.lastname: Virta
authors.forename: Eeva
authors.initials: E
authors.lastname: Eronen-Rasimus
authors.forename: Hermanni
authors.initials: H
authors.lastname: Kaartokallio
mesh_terms: D000217:Acyltransferases / Q000235:genetics*; D001419:Bacteria / Q000201:enzymology* / Q000235:genetics; D002244:Carbon / Q000737:chemistry; D003080:Cold Temperature; D017753:Ecosystem; D005843:Geography; D046448:Ice Cover; D046911:Macromolecular Substances / Q000737:chemistry; D010802:Phylogeny; D012621:Seasons; D012623:Seawater / Q000737:chemistry / Q000382:microbiology*; D017422:Sequence Analysis, DNA
chemical_list: D046911:Macromolecular Substances; D002244:Carbon; D000217:Acyltransferases; C077225:poly(3-hydroxyalkanoic acid) synthase