Functional Insights of the Genus Trinickia, and Description of a Novel Species Trinickia camelliae sp. nov., Isolated from Rhizosphere Soil of Camellia oleifera.

A yellow strain, designated YCB016T, was isolated from rhizosphere soil of Camellia oleifera Abel collected from Xingning city, Guangdong Province, PR China. The strain was aerobic, rod-shaped, without flagella. Phylogenetic analysis of 16S rRNA gene revealed strain YCB016T showed the highest similarities of 98.9% and 98.2% to Trinickia terrae 7GSK02T, Trinickia mobilis DHG64T and Trinickia fusca GDMCC 1.1449T, respectively. The phylogenomic tree revealed strain YCB016T formed a clade with Trinickia violacea DHOD12T. The major cellular fatty acids of strain YCB016T included C16:0, C17:0 cyclo, C19:0 cyclo ɷ8c and summed feature 8. The major polar lipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol and hydroxyphosphatidylethanolamine. The predominant respiratory quinone was ubiquinone-8. The average nucleotide identities (ANI) and the digital DNA-DNA hybridization (dDDH) values among strain YCB016T and all 11 species of the genus Trinickia were 77.7-92.8% and 22.3-50.4%, respectively, which are interspersed on the intra-species cutoff values. The draft genome size of strain YCB016T was 7.3 Mbp with a DNA G + C content of 63.5%. Based on phenotypic, chemotaxonomic, phylogenetic analysis, genomic DNA G + C content, ANI and dDDH values, strain YCB016T represents a novel species of the genus Trinickia, for which the name Trinickia camelliae sp. nov. is proposed. The type strain is YCB016T (= GDMCC 1.3849T = JCM 36232T). Additionally, strain YCB016T produced siderophore, cellulase and lipase whereas T. fusca GDMCC 1.1449T produced siderophore and indoleacetic acid (IAA). The Trinickia symbiotica JPY-345T and Trinickia caryophylli DSM 50341T contained nifH and nifD genes while other species did not. The nodD gene was present in all species. Collectively, the genus Trinickia exhibited potential plant growth-promoting activities.