Isolation and characterization of halotolerant Streptomyces radiopugnans from Antarctica soil

• Published in: Letters in applied microbiology Vol. 56; no. 5; pp. 348 - 355
• Main Authors: Bhave, S.V., Shanbhag, P.V., Sonawane, S.K., Parab, R.R., Mahajan, G.B.
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell 01-05-2013; Oxford University Press
• Subjects: actinomycetes; Antarctic Regions; Antarctica; antibacterial; Biological and medical sciences; DNA, Bacterial - genetics; DNA, Ribosomal - genetics; Fundamental and applied biological sciences. Psychology; Gamma Rays; Genes, rRNA; halotolerant; Hot Temperature; Microbiology; Molecular Sequence Data; Phylogeny; radiation; radiopugnans; RNA, Ribosomal, 16S - genetics; Salt-Tolerance; Soil Microbiology; Streptomyces; Streptomyces - classification; Streptomyces - genetics; Streptomyces - isolation & purification; Streptomyces - physiology; streptomycetes; Antarctica; Antarctic Regions; Halotolerance; Streptomycetaceae; halotolerant; Applied microbiology; Radiation; Streptomyces; antibacterial; Actinomycetales; Characterization; Soils; radiopugnans; Bacteria; Isolation; Actinomycetes; Antarctica; Antibacterial agent; streptomycetes
• ISSN: 0266-8254; 1472-765X
• DOI: 10.1111/lam.12054

An actinomycete wild strain PM0626271 (= MTCC 5447), producing novel antibacterial compounds, was isolated from soil collected from Antarctica. The taxonomic status of the isolate was established by polyphasic approach. Scanning electron microscopy observations and the presence of LL‐Diaminopimelic acid in the cell wall hydrolysate confirmed the genus Streptomyces. Analysis of 16S rRNA gene sequence showed highest sequence similarity to Streptomyces radiopugnans (99%). The phylogenetic tree constructed using near complete 16S rRNA gene sequences of the isolate and closely related strains revealed that although the isolate fell within the S. radiopugnans gene subclade, it was allocated a different branch in the phylogenetic tree, separating it from the majority of the radiopugnans strains. Similar to type strain, S. radiopugnans R97T, the Antarctica isolate displayed thermo tolerance as well as resistance to 60Co gamma radiation, up to the dose of 15 kGy. However, media and salt tolerance studies revealed that, unlike the type strain, this isolate needed higher salinity for its growth. This is the first report of S. radiopugnans isolated from the Antarctica region. The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of Streptomyces radiopugnans MTCC 5447 is JQ723477.
Significance and Impact of the Study
The study presents the first report of isolation of Streptomyces radiopugnans from Antarctica. To date, there is only one publication regarding S. radiopugnans R97T isolated from radiation‐polluted soil. Like the type strain, Antarctica isolate was thermotolerant and radiotolerant, but in addition, it required salts for growth and did not degrade phenol. We envisaged that metabolic pattern of the same species varies based on acclimatization in its native ecological habitat. Additionally, Antarctica isolate had produced novel antibacterial compounds (patent‐US2012/0156295). The study highlighted that least explored extreme regions like Antarctica are rich resources of novel microbial strains producing novel bioactive compounds.
Significance and Impact of the Study: The study presents the first report of isolation of Streptomyces radiopugnans from Antarctica. To date, there is only one publication regarding S. radiopugnans R97T isolated from radiation‐polluted soil. Like the type strain, Antarctica isolate was thermotolerant and radiotolerant, but in addition, it required salts for growth and did not degrade phenol. We envisaged that metabolic pattern of the same species varies based on acclimatization in its native ecological habitat. Additionally, Antarctica isolate had produced novel antibacterial compounds (patent‐US2012/0156295). The study highlighted that least explored extreme regions like Antarctica are rich resources of novel microbial strains producing novel bioactive compounds.