Denitrificimonas halotolerans sp. nov., a novel species isolated from landfill leachate

Abstract

Abstract A polyphasic taxonomic approach was employed to characterize the strain JX-1T isolated from landfill leachate samples in Wuhan city, Hubei province. Compared to the five most closely related type species, strain JX-1T and Denitrificimonas caeni HY-14T exhibited the highest sequence similarity (96.83%) for 16S rRNA gene, nearly reaching the maximum value of 20.3% for digital DNA-DNA hybridization (DDH), with the highest value of 76.06% for average nucleotide identity (ANI) and the highest value of 78.89% for average amino acid identity (AAI). The genome size of strain JX-1T was 2,778,815 bp with a G + C content of 46.12%. It had a total of 2059 clusters, 2710 proteins, and 498 singletons. The major fatty acids in strain JX-1T were Summed Feature 8 (C18:1ω7c/C18:ω6c)(18.28%), iso-C15:0 (28.52%), and anteiso-C15:0 (13.54%). The respiratory quinones were predominantly Q9 (91.92%) with a minor presence of Q8 (8.08%). The major polar lipids included aminolipid, aminophospholipid, diphosphatidylglycerol, glycolipid, phosphatidylethanolamine, phosphatidylglycerol, and phospholipid. This bacterium showed resilience to elevated salinity and high levels of ammonia nitrogen in physiological experiments. These results of this polyphasic study enabled the genotypic and phenotypic differentiation of the strain analyzed from the closest related species, which confirmed that the strain represented a novel species within the genus Denitrificimonas, for which the name Denitrificimonas halotolerans sp. nov. was proposed with JX-1T (MCCC 1K08958T = CCTCC M2023896T) as the type strain. The strain JX-1T, despite being classified as Denitrificimonas, lacked denitrification-related genes and was solely capable of ammonia assimilation.