Two novel species isolated from wheat rhizospheres in Serbia: Pseudomonas serbica sp. nov. and Pseudomonas serboccidentalis sp. nov.

Abstract

Pseudomonas strains IT-194P, IT-215P, IT-P366T and IT-P374T were isolated from the rhizospheres of wheat grown in soils sampled from different fields (some of them known to be disease-suppressive) located near Mionica, Serbia. Phylogenetic analysis of the 16S rRNA genes and of whole genome sequences showed that these strains belong to two potentially new species, one containing strains IT-P366T and IT-194P and clustering (whole genome analysis) next to P. umsongensis DSM16611T, and another species containing strains IT-P374T and IT-215P and clustering next to P. koreensis LMG21318T. Genome analysis confirmed the proposition of novel species, as ANI was below the threshold of 95% and dDDH below 70% for strains IT-P366T (compared with P. umsongensis DSM16611T) and IT-P374T (compared with P. koreensis LMG21318T). Unlike P. umsongensis DSM16611T, strains of P. serbica can grow on D-mannitol, but not on pectin, D-galacturonic acid, L-galactonic acid lactone and α-hydroxybutyric acid. In contrary to P. koreensis LMG21318T, strains of P. serboccidentalis can use sucrose, inosine and α-ketoglutaric acid (but not L-histidine) as carbon sources. Altogether, these results indicate the existence of two novel species for which we propose the names Pseudomonas serbica sp. nov., with the type strain IT-P366T (=CFBP 9060 T = LMG 32732 T = EML 1791 T) and Pseudomonas serboccidentalis sp. nov., with the type strain IT-P374T (=CFBP 9061 T = LMG 32734 T = EML 1792 T). Strains from this study presented a set of phytobeneficial functions modulating plant hormonal balance, plant nutrition and plant protection, suggesting a potential as Plant Growth-Promoting Rhizobacteria (PGPR).