Flexivirga caeni sp. nov., isolated from activated sludge

Abstract

A Gram-stain-positive, strictly aerobic, non-motile, non-spore-forming and oval-shaped bacterium, designated strain BO-16T was isolated from activated sludge. In this study, we describe the taxonomic characterization and classification of this bacterium by using the polyphasic approach. Growth of BO-16T was observed at 10–40 °C (optimum, 25–37 °C) and at pH 5.0–10.0 (optimum, pH 7.0) on R2A agar. The major fatty acids it contained were iso-C16:0, anteiso-C17:0 and iso-C17 : 0 and the major polar lipids were diphosphatidylglycerol, phosphatidylinositol and phosphatidylethanolamine. This isoprenoid quinones included MK-8 (H4) and MK-8 (H6). The peptidoglycan contained lysine, serine, alanine, glycine and glutamic acid and represented the peptidoglycan type A4α. On the basis of 16S rRNA gene sequence similarity, BO-16T was shown to represent a member of the genus Flexivirga and to be related to Flexivirga oryzae KACC 18597T (98.4 % sequence similarity), Flexivirga endophytica KCTC 39536T (97.5 %), Flexivirga alba DSM 24460T (97.4 %) and Flexivirga lutea KCTC 39625T (97.3 %). The G+C content of the genomic DNA was 68.0 mol%. The DNA–DNA relatedness values between BO-16T and its closest phylogenetic neighbours were much lower than 70 %. BO-16T could be differentiated phylogenetically and phenotypically from the species of the genus Flexivirga with validly published names. Therefore the isolate represents a novel species, for which the name Flexivirga caeni sp. nov. is proposed, with the type strain BO-16T (=KACC 19647T=LMG 30859T)

Endophytic Bacterium Flexivirga meconopsidis sp. nov. with Plant Growth-Promoting Function, Isolated from the Seeds of Meconopsis integrifolia

“…Genomic ANI and dDDH analyses, together with physiological and biochemical analyses, confirmed that strain Q11 T is a novel species of the genus Flexivirga. Compared with the reported strains of the genus Flexivirga [1][2][3][4][5][6], strain Q11 T has the abilities of nitrogen fixation (181.80 IU/L), IAA production (3.26 mg/L in 2 days), and plant growth promotion, this last function being described for the first time for the genus Flexivirga. Previous research showed that endophytes promote plant growth through nitrogen fixation, phosphorus dissolution, and growth hormone production [12,79].…”

“…The genus Flexivirga, a member of the Phylum Actinobacteria, was first described by Anzai et al [1]. The List of Prokaryotic Names with Standing in Nomenclature (https://lp sn.dsmz.de/search?word=Flexivirga, accessed on 8 October 2023) contains six species with legitimately recognized names, i.e., Flexivirga alba [1], Flexivirga endophytica [2], Flexivirga lutea [3], Flexivirga oryzae [4], Flexivirga caeni [5], and Flexivirga aerilata [6], which were isolated from the leaves of basil [2], the feces of ibis [3], the soil of a rice paddy [4], activated sludge [5], and an automobile air conditioning system [6], respectively. All members of the genus Flexivirga are described as Gram-positive bacteria, aerobic, non-motile, and with a high G + C content in their DNA (~67 mol%).…”