Comparison of methods for Laribacter hongkongensis strain storage

ObjectiveTo compare different methods for preserving Laribacter hongkongensis (LH) strains and to develop a simple and practicable preservation protocol for short- and long-term storage and reactivation LH strain.MethodsThe five methods for LH strain storage included:(i) semisolid with paraffin storage,(ii) Microbank vial,(iii) 10% glycerol,(iv) 15% glycerol/85% Luria-Bertani (LB) broth culture,and (v) 30% glycerol/70% LB broth culture.The LH strains were put at 4 ℃ and room temperature when using methods i,while the stains were disposed at conventional freezing temperatures of -20 ℃ and -80 ℃ when using other methods,respectively.All storage techniques were evaluated periodically by counting with colony-forming unit over 12 months.ResultsFor semisolid with paraffin storage,the viable strains were reduced gently up to 6 months at room temperature,then reduced rapidly and LH colonies became pinpoint size,contrasting with no colony growth on MacConkey agar at 3-month at 4 ℃.Preservation of LH strains in Microbank vial,10% glycerol,15% glycerol broth,and 30% glycerol broth stored at -80 ℃ were proved to be stable for up to 12 months.However,recovery of the strains from these methods stored at -20 ℃ showed poor growth after one month.ConclusionSemisolid with paraffin storage at room temperature is an effective way for short-term preservation of LH strain.Preservation in glycerol or Microbank vial at -80 ℃ is recommended for prolonged periods of LH strain storage.