mycobacterium lacus mycobacterium lacus mycobacterium lacus is a species of bacteria in the genus mycobacterium known to be a causative agent in immunocompetent individuals. mycobacterium lacus scientific classification domain: bacteria phylum: actinomycetota class: actinomycetia order: mycobacteriales family: mycobacteriaceae genus: mycobacterium species: m. lacus binomial name mycobacterium lacusturenne et al. 2002, atcc baa-323 description large, dispersed acid-fast bacilli with prominent beading colony characteristics colonies on löwenstein–jensen medium were nonchromogenic, small, with a dry appearance. on middlebrook 7h10 agar, colonies are small, non-pigmented and smooth to rough, with a slightly irregular edge. younger colonies appeared slightly transparent. physiology growth was observed on löwenstein–jensen medium at two weeks at both 37 and 42 °c and at 3 weeks at 30 °c. at four weeks, very little growth was observed at 25 °c, and no growth was observed at 52 °c. pathogenesis the causative agent of bursitis in an immunocompetent individual. type strain isolated from synovial tissue from a 68-year-old female with bursitis of her right elbow. the likely exposure was in a lake. strain nrcm 00-255 = atcc baa-323 = dsm 44577