Diversity of hydrolytic enzymes in haloarchaeal strains isolated from salt lake

Abstract

Production of ten hydrolytic enzymes was qualitatively studied on the haloarchaeal strains isolated from Aran-o-bidgol hypersaline lake in the central desert area of Iran. A total of 293 haloarchea strains were selected among 300 extremely halophilic isolated prokaryotes. Of them 142, 141, 128, 64, 38, 16, 7, 3 and 1 archaeal isolates were able to produce DNase, amylase, lipase, inulinase, pullulanase, protease, cellulose, chitinase and xylanase, respectively. None was able to produce pectinase activity. Combined hydrolytic activity was also detected in many strains. One strain showed 6 hydrolytic activities, 1 strain had 5 hydrolytic activities, 16 strains presented 4 hydrolytic activities, 73 strains presented 3 hydrolytic activities, 81 strains presented 2 hydrolytic activities, 53 strains presented 1 hydrolytic activity. According to their phenotypic characteristics and comparative partial 16S rRNA sequence analysis, the halophilic strains were all identified as members of family Halobacteriaceae within 12 different taxa from the following genera: Halorubrum, Haloarcula, Natrinema, Halovivax and Natronomonas. Most enzymes production rate was observed in the genera Halorubrum, Haloarcula and Natrinema whereas; there was not any detectable amount of enzyme production in the genera Halovivax and Natronomonas. The most hydrolytic isolate with 6 combinatorial enzyme production belonged to the genus Natrinema.