Deinococcus hibisci sp. nov., isolated from rhizosphere of Hibiscus syriacus L. (mugunghwa flower)

Abstract

A Gram-stain-positive, pink-pigmented, coccus-shaped, strictly aerobic, non-motile bacterium, strain THG-AG1.5, was isolated from rhizosphere of Hibiscus syriacus L. (Mugunghwa flower) located in Kyung Hee University, Yongin, Gyeonggi, Republic of Korea. The isolated strain grew optimally at 25-30 °C, at pH 6.0-7.5 and in the presence of additional 0-1.5 % (w/v) NaCl. Strain THG-AG1.5 exhibited tolerance to UV radiation (>1500 J m) and to gamma radiation (>12 kGy). Based on 16S rRNA gene sequence comparisons, strain THG-AG1.5 was closely related to Deinococcus daejeonensis MJ27 (98.03 %), Deinococcus radiotolerans C1 (97.61 %) and Deinococcus grandis DSM 3963 (97.32 %). The genomic DNA G+C content of strain THG-AG1.5 was 74.8 mol%. The DNA-DNA hybridization values between strain THG-AG1.5 and its closest phylogenetically neighbours were below 63.0 %. The peptidoglycan amino acids were alanine, valine, glutamic acid, glycine, ornithine, lysine and aspartic acid. Strain THG-AG1.5 contained ribose, mannose and glucose as whole-cell-wall sugars and menaquinone-8 (MK-8) as the only isoprenoid quinone. The major component in the polyamine pattern was spermidine. The major polar lipids of strain THG-AG1.5 were a phosphoglycolipid, six unidentified glycolipids and an unidentified aminophospholipid. The major fatty acids were identified as iso-C15 : 0, C15 : 1ω6c, C16 : 0, iso-C17 : 0, C17 : 0, C18 : 0 and summed feature 3. On the basis of our polyphasic taxonomy study, strain THG-AG1.5 represents a novel species within the genus Deinococcus, for which the name Deinococcushibisci sp. nov. is proposed. The type strain is THG-AG1.5 (=KACC 18850=CCTCC AB 2016078).

Deinococcus terrestris sp. nov., a gamma ray- and ultraviolet-resistant bacterium isolated from soil

“…To determine the tolerance to UV radiation, cells grown to the exponential phase (24 h) in CY liquid medium were harvested, washed with saline (0.85 % NaCl, w/v) and then 10-fold diluted serially [4,32]. Different dilutions of the cell suspension (0.1 ml) were spread onto CY agar plates in triplicate.…”

“…To determine resistance to ionizing radiation, cells grown to the exponential phase were harvested, resuspended with saline and OD 600 adjusted to 1.0 [35]. The cell suspensions were irradiated under a cobalt-60 gamma irradiator with dosages of 3, 6, 9, 12 and 15 kGy [32].…”