Rhodococcus psychrotolerans sp. nov., isolated from rhizosphere of Deschampsia antarctica

Abstract

A novel actinobacterium, designated strain CMAA 1533, was isolated from the rhizosphere of Deschampsia antarctica collected at King George Island, Antarctic Peninsula. Strain CMAA 1533 was found to grow over a wide range of temperatures (4-28 °C) and pH (4-10). Macroscopically, the colonies were observed to be circular shaped, smooth, brittle and opaque-cream on most of the culture media tested. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CMAA 1533 belongs to the family Nocardiaceae and forms a distinct phyletic line within the genus Rhodococcus. Sequence similarity calculations indicated that the novel strain is closely related to Rhodococcus degradans CCM 4446, Rhodococcus erythropolis NBRC 15567 and Rhodococcus triatomae DSM 44892 (≤ 96.9%). The organism was found to contain meso-diaminopimelic acid, galactose and arabinose in whole cell hydrolysates. Its predominant isoprenologue was identified as MK-8(H) and the polar lipids as diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannosides. The major fatty acids were identified as Summed feature (C ω6c and/or C ω7c), C, C ω9c and 10-methyl C. The G+C content of genomic DNA was determined to be 65.5 mol%. Unlike the closely related type strains, CMAA 1533 can grow at 4 °C but not at 37 °C and was able to utilise adonitol and galactose as sole carbon sources. Based on phylogenetic, chemotaxonomic and physiological data, it is concluded that strain CMAA 1533 (= NRRL B-65465 = DSM 104532) represents a new species of the genus Rhodococcus, for which the name Rhodococcus psychrotolerans sp. nov. is proposed.

Actinobacteria from Antarctica as a source for anticancer discovery

“…Based on phylogenetic, phenotypic and chemotaxonomic data, a new actinobacterial species isolated from D. antarctica was recently identified, named Rhodococcus psychrotolerans sp. nov 12 .…”

“…Thus, bioprospecting studies have advanced into auspicious ecological niches, which tend to favour the prevalence of exotic metabolisms and endemic species 10 , 11 . In this context, the Antarctic continent has been considered one of the most promising bioprospecting ecosystems and a valuable source to isolate new and diverse microorganisms due to its environmental peculiarities, such as extremely low temperatures and precipitation, high levels of UV radiation, ocean flooding, high salinity rates, and large unexplored areas 12 – 16 .…”

“…Compound classes belonging to the peptides, polyketides, macrolides, quinolones and others represent these bioactivities [28][29][30][31][32] . Accordingly, the isolation and identification of actinomycetes have become a fruitful area of research in recent years that has subsequently led to the identification of novel Actinomycete species that should be exploited to unveil possible biosynthetic pathways and discover new bioactive natural products 12,[33][34][35] . Thus, the rhizosphere bacterial composition of Antarctic hairgrass (Fig.…”

Sequence analysis of 16S rDNA, gyrB and alkB genes of plant-associated Rhodococcus species from Tunisia

“…R. cercidiphylli, R. artemisiae and R. gannanensis have been found as endophytes of leaves of Cercidiphyllum japonicum, stems of Artemisia annua and roots of Helianthus annuus, respectively [17][18][19]. Rhodococcus kunmingensis and R. psychrotolerans are rhizospheric species living in association with Taxus chinensis and Deschampsia antarctica plants, respectively [20,21]. Other Rhodococcus isolates were found to be living in association with Origanum vulgare [22] and Arabidopsis thaliana [23,24].…”

Antagonistic and plant growth promoting properties of actinomycetes from rhizosphere Deschampsia antarctica E. Desv. (Galindez Island, Antarctica)

“…Streptomycetes were isolated from the rhizosphere of this plant (Livingston Island) and evaluated their antagonistic properties (Encheva et al, 2013). A new species of rhodococcus was isolated from microbial association of D. antarctica on the King George Island (Silva L. J et al, 2018).…”