Carboxyl ester hydrolases production and growth of a halophilic archaeon, Halobacterium sp. NRC-1.
The capability of Halobacterium sp. NRC-1 to synthesize carboxyl ester hydrolases was investigated, and the effect of physicochemical conditions on the growth rate and production of esterases was evaluated. The haloarchaeon synthesized a carboxyl ester hydrolase, confirming the genomic prediction. This enzymatic activity was intracellularly produced as a growth-associated metabolite. Esterase activity was assayed using different p-nitrophenyl-esters and triacyl-glycerides, which showed a preference for hydrolyzing tributyrin. The archaeal growth rate and esterase production were significantly influenced by the pH and the NaCl concentration. An interaction effect between temperature and NaCl was also seen. The maximal growth rate and esterase production found for Halobacterium sp. NRC-1 were 0.136 h(-1) (at 4.2 M NaCl, pH 6 and 44 degrees C) and 1.64 U/l (at 4.6 M NaCl, pH 6 and 30 degrees C), respectively. Furthermore, the effects of NaCl concentration, pH and temperature on enzyme activity were studied. Two maximal esterase activities were elucidated from the intracellular crude extract when it was incubated at different NaCl concentrations (1 M and 5 M) and at different pHs (6 and 7.5). This is the first report that shows experimentally the synthesis of carboxyl ester hydrolases by Halobacterium sp. NRC-1. This enzyme was found to be extremely halophilic (5 M NaCl) and thermophilic (80 degrees C), making it very interesting for future investigations in non-aqueous biocatalysis.
Camacho
Rosa María
RM
Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco A.C., Av. Normalistas 800, Guadalajara, Jalisco, Mexico. camachros@gmail.com
Mateos-Díaz
Juan Carlos
JC
Diaz-Montaño
Dulce María
DM
González-Reynoso
Orfil
O
Córdova
Jesús
J
D019843:Archaeal Proteins / Q000096:biosynthesis*; D043182:Carboxylesterase / Q000096:biosynthesis*; D006217:Halobacterium / Q000201:enzymology* / Q000254:growth & development*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D054712:Salinity; D012965:Sodium Chloride / Q000494:pharmacology
D019843:Archaeal Proteins; D012965:Sodium Chloride; D043182:Carboxylesterase