title: Desiccation tolerance ofBotryococcus braunii(Trebouxiophyceae, Chlorophyta) and extreme temperature tolerance of dehydrated cells.
abstract: Botryococcus brauniiKützing, a green colonial microalga, occurs worldwide in both freshwater and brackish water environments. Despite considerable attention toB. brauniias a potential source of renewable fuel, many ecophysiological properties of this alga remain unknown. Here, we examined the desiccation and temperature tolerances ofB. brauniiusing two newly isolated strains BOD-NG17 and BOD-GJ2. Both strains survived through 6- and 8-month desiccation treatments but not through a 12-month treatment. Interestingly, the desiccation-treated cells ofB. brauniigained tolerance to extreme temperature shifts, i.e., high temperature (40 °C) and freezing (-20 °C). Both strains survived for at least 4 and 10 days at 40 and -20 °C, respectively, while the untreated cells barely survived at these temperatures. These traits would enable long-distance dispersal ofB. brauniicells and may account for the worldwide distribution of this algal species. Extracellular substances such as polysaccharides and hydrocarbons seem to confer the desiccation tolerance.
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki 305-8577 Japan ; National Institute for Environmental Studies, Onogawa 16-2, Tsukuba, Ibaraki 305-8506 Japan.
authors.forename: Mikihide
authors.initials: M
authors.lastname: Demura
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki 305-8577 Japan ; National Institute for Environmental Studies, Onogawa 16-2, Tsukuba, Ibaraki 305-8506 Japan.
authors.forename: Motohide
authors.initials: M
authors.lastname: Ioki
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki 305-8577 Japan ; National Institute for Environmental Studies, Onogawa 16-2, Tsukuba, Ibaraki 305-8506 Japan.
authors.forename: Masanobu
authors.initials: M
authors.lastname: Kawachi
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki 305-8577 Japan ; National Institute for Environmental Studies, Onogawa 16-2, Tsukuba, Ibaraki 305-8506 Japan.
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Nakajima
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki 305-8577 Japan.
authors.forename: Makoto M
authors.initials: MM
authors.lastname: Watanabe
keywords: Algal dispersal; Botryococcus braunii; Desiccation tolerance; Polysaccharide; Temperature tolerance