RESUMO
A halophilic archaeaon, strain LT12T, was isolated from saline soil sampled at the Tarim Basin, PR China. The novel strain stained Gram-negative, cells were rod-shaped, and formed light red-pigmented colonies on agar plate. Strain LT12T grew optimally at 3.1 M NaCl, 0.05 M MgCl2, 37 °C and pH 7.5. The cells lysed in distilled water and the minimal NaCl concentration to prevent cell lysis was 1.4 M. Based on the results of phylogenetic analyses of the 16S rRNA and rpoB' genes, strain LT12T was most closely related to Halostella salina CBA1114T(94.4-95.9â and 93.6â% similarities, respectively). The average nucleotide identity and in silico DNA-DNA hybridization values between strain LT12T and H. salina CBA1114T were 81.0 and 24.3â%, respectively. The major polar lipids of strain LT12T were phosphatidic acid, phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and three unidentified glycolipids. The DNA G+C content was 67.2 molâ% (genome). Based on the phenotypic, chemotaxonomic and phylogenetic properties, strain LT12T represents a novel species of the genus Halostella for which the name Halostellalimicola sp. nov. is proposed. The type strain is LT12T (=CGMCC 1.14941T=JCM 30667T).
Assuntos
Halobacteriaceae/classificação , Filogenia , Salinidade , Microbiologia do Solo , Técnicas de Tipagem Bacteriana , Composição de Bases , China , DNA Arqueal/genética , DNA Bacteriano/genética , Ácidos Graxos/química , Genes Bacterianos , Glicolipídeos/química , Halobacteriaceae/isolamento & purificação , Hibridização de Ácido Nucleico , Fosfolipídeos/química , Pigmentação , RNA Ribossômico 16S/genética , Análise de Sequência de DNARESUMO
OBJECTIVE: We aimed to characterize a novel SGNH (Ser-Gly-Asn-His) family hydrolase from the annotated genome of marine bacteria with new features. RESULTS: A novel esterase Ali5 from Altererythrobacter ishigakiensis has been identified and classified into SGNH family. Ali5 presented a novel GNSL (Gly-Asn-Ser-Leu(X)) motif that differs from the classic GDSL (Gly-Asp-Ser-Leu(X)) motif of SGNH family. The enzyme has esterase and thioesterase activity and exhibited apparent temperature and pH optima of 40 °C and pH 7.5 (in phosphate buffer), respectively. Ali5 was found to be halotolerant and thermostable, and exhibited strong resistance to several organic solvents and metal ions. The residue Tyr196 has a great influence on the catalytic activity, which was proved by site-directed mutagenesis and subsequent kinetic characterization. CONCLUSION: The esterase Ali5 with esterase and thioesterase activities, salt and metal ions resistance and unique structural features was identified, which holds promise for research on the SGNH family of hydrolases.