Diversity of hydrolytic enzymes in haloarchaeal strains isolated from salt lake

Production of ten hydrolytic enzymes was qualitatively studied on the haloarchaeal strains isolated from Aran-Bidgol hypersaline lake in the central desert area of Iran. A total of 293 haloarchea strains were selected among 300 extremely halophilic isolated prokaryotes. Accordingly, 142, 141, 128, 64, 38, 16, 7, 3 and 1 archaeal isolates were able to produce DNase, amylase, lipase, inulinase, pullulanase, protease, cellulase, chitinase and xylanase, respectively. None was able to produce pectinase activity. Combined hydrolytic activity was also detected in many strains. A total of 0.3% of the strains showed 6 hydrolytic activities, 0.3% of the strains had 5 hydrolytic activities, 5.4% of the strains presented 4 hydrolytic activities, 25% of the strains presented 3 hydrolytic activities, 28% of the strains presented 2 hydrolytic activities and 18% of the 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. This investigation showed that the extreme halophilic archaea from Aran-Bidgol lake are a potential source of hydrolytic enzyme under stress conditions and may have possess commercial value

[Isolation of a moderately halophilic bacterium resistant to some toxic metals from Aran and Bidgol Salt Lake and its phylogenetic characterization by 16S rDNA gene]

Heavy metals are toxic for human beings, animals and even plants. For example, nickel causes contact hypersensitivity and also may have carcinogenic effects in human. There are physicochemical and biological methods for removing these elements from environment. Some bacteria are able to remove these elements. In this study, the resistance of bacteria in Aran and Bidgol Salt Lake to heavy metals has been evaluated. Seven bacterial samples of the lake were transferred to Ventosa culture medium. Isolated colonies were grown on the medium containing nickel. The resistant bacteria were transferred to media containing other heavy metal elements. Biochemical, morphological and phylogenetic studies were done based on sequencing of 16S rDNA gene in order to identify the isolated resistant bacterium. In addition, enzymatic potency of the bacteria was evaluated for determination of biotechnological value. 16s rDNA sequencing was applied only for one [out of 46] isolated halophilic bacterium. The bacterium displayed a good potency for growing up in the medium containing 2.5-10% NaCl with a considerable tolerance to nickel and other heavy metals. A bacterium with 98% homology with Salinovibrio costicola species is resistant to some toxic metals and it also has the potency of removing nickel from the contaminated environment and producing some industrial enzymes

Isolation and characterization of a novel native bacillus strain capable of degrading diesel fuel

The ability of native bacteria to utilize diesel fuel as the sole carbon and energy source was investigated in this research. Ten bacterial strains were isolated from the oil refinery field in Tehran, Iran. Two biodegradation experiments were performed in low and high [500 and 10000 ppm, respectively] concentration of diesel fuel for 15 days. Only two isolates were able to efficiently degrade the petroleum hydrocarbons in the first test and degraded 86.67% and, 80.60% of diesel fuel, respectively. The secondary experiment was performed to investigate the toxicity effect of diesel fuel at high concentration [10000 ppm]. Only one strain was capable to degrade 85.20% of diesel fuel at the same time [15 days]. Phenotype and phylogeny analysis of this strain was characterized and identified as dieseldegrading bacteria, based on gram staining, biochemical tests, 16S rRNA gene sequence analysis. These results indicate that this new strain was Bacillus sp. and could be considered as Bacillus Cereus with 98% 16 S rRNA gene sequence similarity. The results indicate that native strains have great potential for in situ remediation of diesel-contaminated soils in oil refinery sites