Antrihabitans spumae sp. nov., a novel bacterium isolated from stable foams formed in wastewater treatment plants, and emended description of the genus Antrihabitans

Three strains, designated as J27, J71T 31 , and J72, belonging to the genus Antrihabitans, were isolated from stable foams formed in activated sludge wastewater treatment plants (WWTPs) in New South Wales, Australia. Phenotypic and genomic analyses revealed that these strains belong to the Nocardiaceae family and are closely related to Antrihabitans stalagmiti. However, distinct genomic and physiological characteristics, including OGRI, phylogenomic analysis, genomic metabolic profiles and MALDI-TOF mass spectrometry, confirmed their status as a new species.

Ecologically, these strains showed a wide metabolic versatility, like enhanced membrane transport systems for amino acids, metals, and phosphate, as well as the ability to synthesize mycolic acids, contributing to their hydrophobic nature and involvement in foam stabilization. Their adaptations likely provide a competitive advantage in WWTPs, where they persist in nutrient-rich, metal-laden, and foam-stabilizing environments. The species did not present the typical rod-coccus cycle, described previously as a defining characteristic of the Antrihabitans genus. Based on their unique genomic, phenotypic, and ecological features, we propose the name Antrihabitans spumae sp. nov., with strain J71T (JCM 34493T, NCIMB 15450T 45 ) designated as the type strain. Additional strains include J27 (JCM 33914, NCIMB 15449) and J72 (NCIMB 47 15448).