Abstract
Pseudomonas are ubiquitously occurring microorganisms and are known for their ability to produce antimicrobials. An endophytic bacterial strain NP-1 T, isolated from Eucalyptus dunnii leaves, exhibits antifungal properties against five tested phytopathogenic fungi. The strain is a Gram-negative rod-shaped bacterium containing a single polar flagellum. It is strictly aerobic, grows at 4–37 °C, 2–5% NaCl, and pH 3–7. The 16S rRNA sequence analysis showed that NP-1 T belongs to the Pseudomonas genus. Phylogenetic analysis based on four concatenated partial genes (16S rDNA, gyrB, rpoB and rpoD) and the phylogenomic tree indicated that NP-1 T belongs to Pseudomonas fluorescens lineage but is distinct from any known Pseudomonas species. The G + C mol % of NP-1 T genome is 63.96, and the differences between NP-1 T and related species are larger than 1. The digital DNA-DNA hybridization and tetranucleotide signatures are 23.8 and 0.97, which clearly separates strain NP-1 T from its closest neighbours, Pseudomonas coleopterorum and Pseudomonas rhizosphaerae. Its phenotypic and chemotaxonomic features confirmed its differentiation from related taxa. The results from this polyphasic approach support the classification of NP-1 T as a novel species of Pseudomonas, and the name of Pseudomonas eucalypticola is thus proposed for this strain, whose type is NP-1 T (= CCTCC M2018494T = JCM 33572 T).
Highlights
The genus Pseudomonas belongs to the family Pseudomonadaceae within γ-Proteobacteria and is composed of Gram-negative, aerobic, non-spore forming rod-shaped bacteria that are motile by polar flagella[1]
A 1444 bp fragment of the 16S rRNA gene was amplified from the P. eucalypticola strain NP-1 T, sequenced and the sequence deposited in GenBank under accession number MN 238,862
Strain NP-1 T grouped in none known group or subgroup within P. fluorescens lineage, and it clusters of the outer edge of a much larger group containing several Pseudomonas groups/subgroups
Summary
The genus Pseudomonas belongs to the family Pseudomonadaceae within γ-Proteobacteria and is composed of Gram-negative, aerobic, non-spore forming rod-shaped bacteria that are motile by polar flagella[1]. New species belonging to the genus are continuously isolated from a variety of natural ecological niches, including the plant endosphere[1,2,3]. For the identification of each new species of Pseudomonas, phenotypical and chemotaxonomical analyses, multilocus sequence analysis (MLSA), and genomic comparisons should be p erformed[5,6,7,8,9]. Some Pseudomonas species are well known for their pathogenicity to plants, animals or humans[10], and several members are used for bioremediation and as biocontrol a gents[11]. One bacterial isolate NP-1 T could inhibit C. pseudoreteaudii mycelial growth, and the culture filtrate of NP-1 T was capable of controlling this plant disease in vitro. Antifungal tests revealed that, NP-1 T inhibited five tested phytopathogenic fungal species, which shows that NP-1 T has a broad antimicrobial spectrum
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