Diversity and enzyme properties of protease-producing bacteria isolated from sub-Antarctic sediments of Isla de Los Estados, Argentina |
| |
Authors: | Nelda L Olivera Cynthia Sequeiros Marina L Nievas |
| |
Institution: | (1) Centro Nacional Patagónico (CENPAT, CONICET), Blvd. Brown s/n, Puerto Madryn, U9120ACF Chubut, Argentina;(2) Universidad Nacional de La Patagonia San Juan Bosco, Sede Puerto Madryn, Chubut, Argentina |
| |
Abstract: | 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 Colwellia aestuarii form a distinct lineage within the genus. The remaining isolates were psychrotolerant and grew optimally between 20 and 25°C;
two of them represent potentially novel species or genus (16S rRNA < 97% sequence similarity). The thermostability of the
extracellular proteases produced by the isolates was analysed, and the inactivation rate constant (k
in), the activation energy (Eain) and the activation Gibbs free energy of thermal inactivation (ΔG
*
in) determined. ΔG
*
in, calculated at 30°C, 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 varies considerably among the isolates,
suggesting important variations in the thermal properties of the proteases that can coexist in this environment. |
| |
Keywords: | Sub-Antarctic Cold-active proteases Thermostability Psychrophiles Psychrotolerants |
本文献已被 PubMed SpringerLink 等数据库收录! |
|