OLIVERA nelda Lila
Diversity and enzyme properties of protease-producing bacteria isolated from sub-Antarctic sediments of Isla de los Estados, Argentina.
NELDA LILA OLIVERA; CYNTHIA SEQUEIROS,; MARINA NIEVAS
Lugar: Tokyo; Año: 2007 vol. 11 p. 517 - 517
Protease-producing bacteria isolated from sub-Antarctic marine sediments of Isla de Los Estados (Argentina) were characterized, and the thermal inactivation kinetics of their extracellular proteases compared. Isolates were affiliated with the genera Pseudoalteromonas, Shewanella, Colwellia, Planococcus, and a strain to the family Flavobacteriaceae. Colwellia strains were moderate psychrophiles (optimal growth at about 15°C, maximum growth temperature at around 25°C). 16S rRNA phylogenetic analysis revealed that these strains and C. aestuarii form a distinct lineage within the genus. The remaining isolates were psychrotolerant and grew optimally between 20-25°C; 2 of them represent potentially novel species or genus (16S rRNA < 97 % sequence similarity). The thermostability of the extracellular proteases produced by the isolates were analyzed, and the inactivation rate constant (kin), the activation energy (Eain) and the activation Gibbs free energy of thermal inactivation (deltaG*in) determined. deltaG*in, calculated at 30ºC, varied between 97 and 124 kJ/mol. Colwellia enzyme extracts presented the highest thermosensitivity, while the most thermostable protease activity was shown by Shewanella spp. These results demonstrated that the stability to temperature of these enzymes vary considerably among the isolates, suggesting important variations in the thermal properties of the proteases that can coexist in this environment.