Lipolytic activity fromHalobacteria: Screening and hydrolase production

Abstract

Strains of Halobacteria from an Algerian culture collection were screened for their lipolytic activity against p-nitrophenyl butyrate (PNPB) and p-nitrophenyl palmitate (PNPP). Most strains were active on both esters and 12% hydrolyzed olive oil. A strain identified as Natronococcus sp. was further studied. It grew optimally at 3.5 M NaCl, pH 8 and 40 degrees C. An increase in temperature shifted the optimum salt concentration range for growth from a wider range of 2-4 M, obtained at 25-30 degrees C, to a narrower range of 3.5-4 M, obtained at 35-40 degrees C. At 45 degrees C the optimum salt concentration was 2 M. These results show a clear correlation between salt and temperature requirement. The optimum conditions for the production of hydrolytic activity during growth were: 3.5 M NaCl and pH 8 for PNPB hydrolytic activity and 4 M NaCl and pH 7.5 for PNPP hydrolytic activity; both at 40 degrees C. The clear supernatant of cells grown at 4 M NaCl showed olive oil hydrolysis activity (in presence of 4 M NaCl) demonstrating the occurrence of a lipase activity in this strain. To our knowledge, this is the first report of a lipase activity at such high salt concentration.

Characterization of extracellular esterase and lipase activities from five halophilic archaeal strains

“…The cultures were grown at 37°C for 12 days. Afterwards, the screening of lipolytic activity of the strains was monitored under UV light at 350 nm as orange halos appearing around the colonies [1,12]. The growth of the selected Wve isolates was determined by the increase in optical density at 600 nm, and lipolytic activity was routinely assayed during 7 days of culture period.…”

Production of organic solvent tolerant lipase by Staphylococcus caseolyticus EX17 using raw glycerol as substrate

“…Lin et al 12 found that glycerol (50 g L −1 ) was the best carbon source for lipolytic activity by Antrodia cinnamomea, obtaining an enzyme activity of 27 U L −1 . Bhatnagar et al, 23 working with halobacteria Natronococcus sp., found the highest lipolytic activity of 45 U L −1 at pH 7.5 and temperature in the range 35-40…”

Biocompounds from Haloarchaea and Their Uses in Biotechnology

“…The biotechnological applications of halophilic lipases and thioesterases have been reviewed recently [69]. Bhatnagar et al isolated 54 Halobacteria from a salt lake in the Algerian Sahara and screened 35 of these strains [70]. Among them, strain TC6 (belonging to the Natronococcus genus) was selected for further study.…”