Lederbergia citri sp. nov., and Lederbergia citrisecundus sp. nov., isolated from citrus rhizosphere.

Abstract

Two Gram-positive, rod-shaped, motile, endospore-forming strains, FJAT-49780T and FJAT-49732T were isolated from a citrus rhizosphere soil sample. The optimal growth temperatures for strains FJAT-49780T and FJAT-49732T were 45 and 35-40°C, respectively. The optimal growth pH for strains FJAT-49732T and FJAT-49780T were pH 8.0 and pH 6.0, respectively. The 16S rRNA gene sequence similarity between FJAT-49780T and FJAT-49732T was 98.6%. Strains FJAT-49780T and FJAT-49732T shared 97.9-98.4% 16S rRNA gene sequence similarities to the type strain of Lederbergia wuyishanensis. In phylogenetic trees (based on 16S rRNA gene sequence), strains FJAT-49732T and FJAT-49780T clade with Lederbergia members. Both strains contained meso-diaminopimelic acid in their cell-wall peptidoglycan and MK-7 was the only isoprenoid quinone detected. The major fatty acids of strains FJAT-49732T and FJAT-49780T were anteiso-C15:0 and iso-C15:0. The polar lipids of strain FJAT-49780T were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, an unidentified aminophospholipid, unidentified phospholipid and unidentified lipids while strain FJAT-49732T contained diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, an unidentified glycolipid, unidentified aminolipid and unidentified phospholipid. The genomic DNA G+C content of strains FJAT-49780T and FJAT-49732T were 37.0 and 36.7%, respectively. The digital DNA-DNA hybridizationand average nucleotide identity values between strains FJAT-49780T and FJAT-49732T and with other members of the genus Lederbergia were below the cut-off level for species delineation. Thus, based on the above results, strains FJAT-49780T and FJAT-49732T represent two novel species of the genus Lederbergia, for which the names Lederbergia citri sp. nov., and Lederbergia citrisecundus sp. nov., are proposed. The type strains are FJAT-49780T (= CCTCC AB 2019242T = LMG 31583T) and FJAT-49732T (= CCTCC AB 2019246T = LMG 31584T).