Bosea caraganae sp. nov. a new species of slow-growing bacteria isolated from root nodules of the relict species Caragana jubata (Pall.) Poir. originating from Mongolia

Abstract

Two Gram-stain-negative strains, RCAM04680^T and RCAM04685, were isolated from root nodules of the relict legume <i>Caragana jubata</i> (Pall.) Poir. originating from the south-western shore of Lake Khuvsgul (Mongolia). The 16S rRNA gene (<i>rrs</i>) sequencing data showed that these novel isolates belong to the genus <i>Bosea</i> and are phylogenetically closest to the type strains <i>Bosea lathyri</i> LMG 26379^T, <i>Bosea vaviloviae</i> LMG 28367^T, <i>Bosea massiliensis</i> LMG 26221^T and <i>Bosea lupini</i> LMG 26383^T (the <i>rrs</i>-similarity levels were 98.7-98.8 %). The <i>recA</i> gene of strain RCAM04680^T showed the highest sequence similarity to the type strain <i>B. lupini</i> LMG 26383^T (95.4 %), while its <i>atpD</i> gene was closest to that of <i>B. lathyri</i> LMG 26379^T (94.4 %). The ITS, <i>dnaK</i> and <i>gyrB</i> sequences of this isolate were most similar to the <i>B. vaviloviae</i> LMG 28367^T (86.8 % for ITS, 90.4 % for the other genes). The most abundant fatty acid was C_{18 : 1}ω7<i>c</i> (40.8 %). The whole genomes of strains RCAM04680^T and RCAM04685 were identical (100 % average nucleotide identity). The highest average nucleotide identity value (82.8 %) was found between the genome of strain RCAM04680^T and <i>B. vaviloviae</i> LMG 28367^T. The common <i>nod</i>ABC genes required for legume nodulation were absent in both strains; however, some other symbiotic <i>nol</i>, <i>nod</i>, <i>nif</i> and <i>fix</i> genes were detected. Based on the genetic study, as well as analyses of the whole-cell fatty acid compositions and phenotypic properties, a new species, <i>Boseacaraganae</i> sp. nov. (type strain RCAM04680^T (=LMG 31125^T), is proposed.