Rossellomorea arthrocnemi sp. nov., a novel plant growth-promoting bacterium used in heavy metal polluted soils as a phytoremediation tool
Salvadora Navarro‐Torre, Lorena Carro, José M. Igual, Maria del Carmen Montero‐Calasanz
Abstract
Strain EAR8 T is a root endophyte isolated from Arthrocnemum macrostachyum plants collected from the Odiel marshes, Huelva (Spain). It presented in vitro plant growth-promoting properties and improved the plant growth and heavy metal accumulation in polluted soils playing an important role in phytoremediation strategies. Phenotypically, strain EAR8 T cells were Gram-positive, aerobic and non-motile rods with terminal oval endospores and non-swollen sporangia which form beige, opaque, butyrous, raised and irregular colonies with undulate margins. The strain was able to grow between 15–45 °C, at pH 6.0–9.0 and tolerated 0–25 % NaCl (w/v) showing optimal growth conditions on trypticase soy agar plates supplemented with 2.5 % NaCl (w/v) at pH 7.0 and 37 °C for 24 h. Chemotaxonomic analyses showed that the isolate has meso -diaminopimelic acid as the peptidoglycan in the cell wall and MK-7 as the major respiratory quinone. The predominant fatty acids were anteiso-C 15 : 0 and iso-C 15 : 0 and the polar lipid profile was composed of diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Phylogenetic analyses based on the whole proteomes of closest sequenced relatives confirmed that strain EAR8 T is affiliated to the genus Rossellomorea and forms a clade with Rossellomorea vietnamensis 15-1 T with maximum support. Genome analyses showed that EAR8 T has indole-3-acetic acid and siderophore biosynthesis and transporters genes and genes related to resistance against heavy metals. Phenotypic and phylogenomic comparative studies suggested that strain EAR8 T is a new representative of the genus Rossellomorea and the name Rossellomorea arthrocnemi sp. nov. is proposed. Type strain is EAR8 T (=CECT 9072 T =DSM 103900 T ).