Preservation of Chloroflexus by deep-freezing and liquid-drying methods

Abstract

Long-term preservation methods for Chloroflexus are described. All tested strains of Chloroflexus aurantiacus and Chloroflexus aggregans were successfully preserved and reactivated within a relatively short time with full pigmentation, indicating that their viability, stability and ability to grow photoautotrophically were not affected. The cultures were preserved in liquid nitrogen under anaerobic conditions using 5% dimethylsulfoxide, 5% methanol or 10% glycerol as cryoprotectants. For easy storage and transport, the cultures were successfully dried in small glass ampoules directly from the liquid phase, without involving freezing under semiaerobic conditions. All tested cultures showed good survival rates after drying and on long-term storage. Cryopreservation, liquid-drying and reactivation in the absence of oxygen proved very effective, as, presumably, they reduce the chance of producing free radicals, which are considered as damaging to living cells.