RESUMO
The Gram-positive, nonmotile, rod-shaped bacterium EF45044T was isolated from a hot spring in Chungju, South Korea. The strain was able to grow at concentrations of 0â5% (w/v) NaCl, at pH 6.0â10.0 and in the temperature range of 18â50 °C. Strain EF45044T showed the highest 16S rRNA gene sequence similarity (98.2%) with Microbacterium ketosireducens DSM 12510T, and the digital DNAâDNA hybridization (dDDH), average amino acid identity (AAI), and average nucleotide identity (ANI) values were all lower than the accepted species threshold. Strain EF45044T contained MKâ12 and MKâ13 as the predominant respiratory quinones and anteisoâC17:0, anteisoâC15:0, and isoâC16:0 as the major fatty acids. Diphosphatidylglycerol, phosphatidylglycerol, and glycolipid were detected as the major polar lipids. The cell-wall peptidoglycan contained ornithine. The DNA G + C content was 71.4 mol%. Based on the polyphasic data, strain EF45044T (= KCTC 49703T) presents a novel species of the genus Microbacterium, for which the name Microbacterium neungamense sp. nov. is proposed.
Assuntos
Ácidos Graxos , Microbacterium , RNA Ribossômico 16S/genética , Microbacterium/genética , Filogenia , Técnicas de Tipagem Bacteriana , DNA Bacteriano/genética , Análise de Sequência de DNA , Ácidos Graxos/análise , Hibridização de Ácido Nucleico , Fosfolipídeos/químicaRESUMO
Thermophiles that produce extracellular hydrolases are of great importance due to their applications in various industries. Thermophilic enzymes are of interest for industrial applications due to their compatibility with industrial processes, and the availability of the organisms is essential to develop their full potential. In this study, a culture-dependent approach was used to identify thermophilic bacteria from five hot springs in Republic of Korea. Characterization, taxonomic identification, and extracellular hydrolase (amylase, lipase, and protease) activity of 29 thermophilic bacterial isolates from the Neungam carbonate, Mungang sulfur, Deokgu, Baegam, and Dongnae hot springs were investigated. Identification based on the full-length 16S rRNA gene sequence revealed that strains belonged to the phylum Bacillota and were classified as Aeribacillus, Bacillus, Caldibacillus, Geobacillus, and Thermoactinomyces genera. It was found that 22 isolates could produce at least one extracellular enzyme. Geobacillus, representing 41.4% of the isolates, was the most abundant. The highest amount of proteolytic and lipolytic enzymes was secreted by strains of the genus Geobacillus, whereas Caldibacillus species produced the highest amount of amylolytic enzyme. The Geobacillus species producing hydrolytic extracellular enzymes appeared to be the most promising.