Phthalate-degrading strain Stutzerimonas sp. SJ1gcor from soil in the coastal zone of a technogenic saline-alkaline reservoir

Abstract

Haloalkaline environments are of particular interest for research, as they are characterized by a unique diversity of extremophilic microorganisms that are adapted to high salinity and alkalinity. Among these extremophilic microorganisms, strains that degrade various aromatic and aliphatic compounds, which have detrimental effects on ecosystems and human health, deserve special attention. Strain SJ1gcor, identified as a member of the genus Stutzerimonas, was isolated from the coastal soil of a technogenic saline-alkaline reservoir located within the Verkhnekamsk potassium-magnesium salt deposit (Berezniki, Perm Krai). Analysis of the 16S rRNA gene of the studied strain revealed the highest level of similarity (99.69%) to the homologous gene of Stutzerimonas zhaodongensis NEAU-ST5-21T. The strain is capable of growing as a sole source of carbon and energy on phthalates: dibutyl phthalate (DBP) and dimethyl phthalate (DMP), as well as the possible degradation products of these compounds: ortho-phthalic acid (OPA), benzoic acid (BA) and butanol. It was demonstrated that the strain is capable of growing on DBP as a substrate with a NaCl content of up to 70 g/L in the culture medium. The highest specific growth rate of the strain SJ1gcor was found when cultivating in a medium containing 30 g/L NaCl, and the maximum optical density was recorded in a medium containing 70 g/L NaCl. The benA gene encoding the α-subunit of benzoate 1,2-dioxygenase, a key enzyme in BA degradation, was identified in the strain's genome. Based on the data obtained, two alternative DBP degradation pathways were proposed for the strain SJ1gcor. Therefore, the strain Stutzerimonas sp. SJ1gcor is of interest for further research and holds promise for biotechnological applications.