P097

1:CNC-UC - Center for Neuroscience and Cell Biology and CIBB - Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, Portugal; 2:PDBEB – PhD Program in Experimental Biology and Biomedicine, Institute for Interdisciplinary Research, University of Coimbra, Portugal; 3:CHVNGE - Centro Hospitalar de Vila Nova de Gaia/Espinho, Unidade Local de Saúde de Gaia e Espinho, Vila Nova de Gaia, Portugal; 4:Department of Life Sciences, University of Coimbra, Portugal; 5:ISPUP - nstituto de Saúde Pública da Universidade do Porto, Universidade do Porto, Rua das Taipas, n° 135, 4050-600 Porto, Portugal; 6:ICBAS - Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal; 7:INSA – Instituto Nacional de Saúde Doutor Ricardo Jorge, INSA Porto, Porto, Portugal

The identification and characterization of novel nontuberculous mycobacteria species are of increasing environmental and clinical relevance, as opportunistic infections by these opportunistic pathogens are on the rise globally. Three isolates of a novel, rapidly growing, non-pigmented Mycobacterium species were recovered from the water and runoff of a public fountain in a rural village in Central Portugal. High-quality draft genome sequencing, in silico DNA-DNA hybridization, and phylogenetic analyses confirmed that the isolated strains 21AC1ᵀ, 21AC14, and 21AC21 represent a previously undescribed species within the genus Mycobacterium, forming a distinct phylogenetic lineage closely related to Mycobacterium wolinskyi, Mycobacterium goodii, and Mycobacterium smegmatis. MALDI-TOF MS analysis of the type strain 21AC1ᵀ revealed a unique spectral profile. A comprehensive polyphasic characterization was performed, including chemotaxonomic analyses of fatty acid and mycolic acid composition, as well as an extensive biochemical characterization. The antimicrobial susceptibility of the three strains to 12 antimicrobials was also assessed.

Based on our findings, we propose that strains 21AC1ᵀ, 21AC14, and 21AC21 represent a novel species within the genus Mycobacterium, for which we propose the name Mycobacterium appelbergii sp. nov. This name is given in honour of Prof. Rui Appelberg, in recognition of his outstanding scientific contributions to the understanding of immune responses, vaccine development, and immunopathology in the context of Mycobacterium avium and Mycobacterium tuberculosis infections.

Strains deposit: 21AC1ᵀ (=BCCM/ITM 501212 = DSM 113570), 21AC14 (=BCCM/ITM 501447 = DSM 118402) and 21AC21 (=BCCM/ITM 501448 = DSM 118403).

Funding: PTDC/BIA-MIC/0122/2021, 2022.06809.PTDC, UIDB/04539/2020, UIDP/04539/2020 and LA/P/0058/2020. Contract DL57/2016-SFRH/BPD/108299/2015 and PhD grant SFRH/BD/145135/2019