Erwinia endophytica sp. nov., isolated from potato (Solanum tuberosum L.) stems

Abstract

We analysed, using a polyphasic taxonomic approach, two bacterial strains coded BSTT30^T and BSTT40, isolated in the course of a study of endophytic bacteria occurring in the stems and roots of potatoes growing in soil from Salamanca, Spain. The 16S rRNA gene sequence was identical in both strains and had 98.4 % identity with respect to the closest relatives <i>Erwinia tasmaniensis</i> Et1/99^T and <i>Erwinia rhapontici</i> ATCC29283^T. <i>Erwinia billingiae</i> E63^T and <i>Erwinia toletana</i> A37^T were also closely related with 98.2 % sequence similarities, so the novel strains were classified within the genus <i>Erwinia</i>. The analysis of the housekeeping genes <i>gpd, gyrB</i> and <i>rpoD</i> confirmed the phylogenetic affiliation of strains BSTT30^T and BSTT40 with similarities of lower than 90 % in all cases with respect to the closest relatives mentioned above. The respiratory quinone of strain BSTT30^T was Q8. The major fatty acids were C16 : 0, C16 : 1ω7<i>c</i>/16 : 1ω6<i>c</i> in summed feature 3 and C18 : 1ω7<i>c</i>/18 : 2ω6,9<i>c</i> in summed feature 8. The novel strains were oxidase-negative and catalase-positive. Glucose was fermented without gas production. They were negative for arginine dihydrolase, urease and indole production. The strains could grow at 35 °C and at pH 10. DNA G+C content was 50.1 mol%. DNA-DNA hybridization results showed values of lower than 29 % relatedness with respect to the type strains of the four most closely related species. Therefore, the combined genotypic, phenotypic and chemotaxonomic data support the classification of strains BSTT30^T and BSTT40 into a novel species of the genus <i>Erwinia</i>, for which the name <i>Erwinia endophytica</i> sp. nov. is proposed. The type strain is BSTT30^T ( = LMG 28457^T, CECT 8692^T).