Modestobacter lacusdianchii sp. nov., a Phosphate-Solubilizing Actinobacterium with Ability to Promote Microcystis Growth

摘要

A novel actinobacterium, designated strain JXJ CY 19^T, was isolated from a culture mat of Microcystis aeruginosa FACHB-905 collected from Dianchi Lake, South-west China. 16S rRNA gene sequences comparison of strain JXJ CY 19^T and the available sequences in the GenBank database showed that the strain was closely related to Modestobacter marinus 42H12-1^T (99.1% similarity) and Modestobacter roseus KLBMP 1279^T (99.0%). The isolate had meso-diaminopimelic in the cell wall with whole-cell sugars of mannose, rhamnose, ribose, glucose, galactose, and arabinose. The menaquinone detected was MK-9(H4), while the major cellular fatty acids include C17:1 ω8c, C15:0 iso, C15:1 iso G and C16:0 iso. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannoside and an unidentified phospholipid. The DNA-DNA hybridization values between strains JXJ CY 19^T and the closely related type strains Modestobacter marinus CGMCC 4.5581^T and Modestobacter roseus NBRC 108673^T were determined to be 50.8 ± 0.8% and 44.1 ± 1.7%, respectively. The DNA G+C content was 71.9 mol%. On the basis of the above taxonomic data and differences in physiological characters from the closely related type strains, strain JXJ CY 19^T was recognized as a novel species of the genus Modestobacter, for which the name Modestobacter lacusdianchii sp. nov. (JXJ CY 19^T = KCTC 39600^T = CPCC 204352^T) is proposed. The type strain JXJ CY 19^T can solubilize calcium phosphate tribasic (Ca3(PO4)2), phytin and L-α-phosphatidylcholine. The phosphate-solubilizing property of the novel actinobacterium could be a possible factor for the increase in growth of Microcystis aeruginosa FACHB-905 in ecosystem where the amount of available soluble phosphate is limited such as Dianchi Lake.