title: Impact of matrix properties on the survival of freeze-dried bacteria.
abstract: BACKGROUND
  Disaccharides are, in general, the first choice as formulation compounds when freeze-drying microorganisms. Although polysaccharides and other biopolymers are considered too large to stabilise and interact with cell components in the same beneficial way as disaccharides, polymers have been reported to support cell survival. In the present study we compare the efficiency of sucrose and the polymers Ficoll, hydroxyethylcellulose, hydroxypropylmethylcellulose and polyvinylalcohol to support the survival of three bacterial strains during freeze drying. The initial osmotic conditions were adjusted to be similar for all formulations. Formulation characterisation was used to interpret the impact that different compound properties had on cell survival.
  
  
  RESULTS
  Despite differences in molecular size, both sucrose and the sucrose-based polymer Ficoll supported cell survival after freeze drying equally well. All formulations became amorphous upon dehydration. Scanning electron microscopy and X-ray diffraction data showed that the discerned differences in structure of the dry formulations had little impact on the survival rates. The capability of the polymers to support cell survival correlated with the surface activity of the polymers in a similar way for all investigated bacterial strains.
  
  
  CONCLUSIONS
  Polymer-based formulations can support cell survival as effectively as disaccharides if formulation properties of importance for maintaining cell viability are identified and controlled.
authors: Department of Microbiology, Uppsala Biocenter, Swedish University of Agricultural Sciences, Box 7025, SE-750 07 Uppsala, Sweden. per.wessman@mikrob.slu.se
authors: Per
authors: P
authors: Wessman
authors: Denny
authors: D
authors: Mahlin
authors: Sultan
authors: S
authors: Akhtar
authors: Stefano
authors: S
authors: Rubino
authors: Klaus
authors: K
authors: Leifer
authors: Vadim
authors: V
authors: Kessler
authors: Sebastian
authors: S
authors: Håkansson
mesh_terms: D001173:Arthrobacter / Q000166:cytology / Q000187:drug effects* / Q000302:isolation & purification; D002152:Calorimetry, Differential Scanning; D002482:Cellulose / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology / Q000648:ultrastructure; D015169:Colony Count, Microbial; D003451:Cryoprotective Agents / Q000737:chemistry* / Q000494:pharmacology*; D005362:Ficoll / Q000737:chemistry / Q000494:pharmacology / Q000648:ultrastructure; D005612:Freeze Drying; D057927:Hydrophobic and Hydrophilic Interactions; D065347:Hypromellose Derivatives; D008747:Methylcellulose / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology; D050296:Microbial Viability / Q000187:drug effects*; D008855:Microscopy, Electron, Scanning; D011142:Polyvinyl Alcohol / Q000737:chemistry / Q000494:pharmacology; D016958:Pseudomonas putida / Q000166:cytology / Q000187:drug effects* / Q000302:isolation & purification; D020578:Sphingomonas / Q000166:cytology / Q000187:drug effects* / Q000302:isolation & purification; D013329:Structure-Activity Relationship; D013395:Sucrose / Q000737:chemistry / Q000494:pharmacology; D013500:Surface Tension; D013501:Surface-Active Agents / Q000737:chemistry / Q000494:pharmacology; D044366:Transition Temperature; D014961:X-Ray Diffraction
chemical_list: D003451:Cryoprotective Agents; D013501:Surface-Active Agents; D005362:Ficoll; D065347:Hypromellose Derivatives; D013395:Sucrose; D011142:Polyvinyl Alcohol; D002482:Cellulose; C002283:hydroxyethylcellulose; D008747:Methylcellulose