Properties of extracellular proteases from three psychrotolerant Stenotrophomonas maltophilia isolated from Antarctic soil

VAZQUEZ SC; RUBERTO LAM; MAC CORMACK WP

POLAR BIOLOGY

Año: 2005 vol. 28 p. 319 - 325

0722-4060

Three Antarctic psychrotolerant Stenotrophomonas maltophilia were isolated and the characteristics of their extracellular serine proteases were described. The isolates were able to grow at 14 and 34 ºC, but grew better between 20 and 28ºC. The highest protease secretion was reached at 20–24ºC. The purified enzyme preparations had maximal activity at 55–60ºC and alkaline pH. They showed high pH stability, retaining more than 60% of residual activity after 3 h of incubation at a pH range of 4–12. The thermal stability was slightly lower compared with a commercial mesophilic protease, with 74–79% residual activity after 90 min at 40ºC and 50% inactivation at 50ºC between 43 and 69 min. These properties suggest that the Antarctic isolates could be adapted to cold by means ofsynthesising more enzymes with high activity but that the proteases they produce are not truly cold-active, being more similar to mesophilic enzymes.