Maintenance of penicillin G acylase expression by B. megaterium: preservation methods and activity recovery

• Autor(a) principal: Pinotti,L. M.
• Data de Publicação: 2007
• Outros Autores: Silva,R. G., Zangirolami,T. C., Giordano,R. L. C.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Brazilian Journal of Chemical Engineering
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322007000300001
• topic: B. megaterium; Cryovials; Cryoprotectors; Penicillin G Acylase; Preservation methods

This work reports the influence of different culture preservation methods on the production of penicillin G acylase (PGA) by Bacillus megaterium ATCC 14945. The initial stock culture, presenting PGA activity of 97 IU l-1, was preserved for two years using different procedures: monthly subculturing and storage in refrigerator (S), freeze-drying using skim milk 10%, plus inositol 5% as cryoprotectors (L1), freeze-drying using sucrose 7%, plus peptone 7% (L2), and freezing with glycerol 10% (F). After cultivations at standard operational conditions, different values of enzyme activity were obtained: 56 IU l-1 for monthly subculturing (S), 15-41 IU l-1 for freeze-dried cells and frozen spores. All the tested methods have failed in preserving the PGA expression. Among all tested cultures, S presented the highest specific activity, and was used to prepare a standard inoculum in cryovials (-50ºC, frozen spores in a 20% glycerol solution). By cultivation of this inoculum under different conditions, it was found that PGA activity raised to 128 IU l-1 when 0.4 g l-1 of salts was added to the medium.