mycobacterium gastri mycobacterium gastri mycobacterium gastri is a species of the phylum actinomycetota (gram-positive bacteria with high guanine and cytosine content, one of the dominant phyla of all bacteria), belonging to the genus mycobacterium. mycobacterium gastri scientific classification domain: bacteria phylum: actinomycetota class: actinomycetia order: mycobacteriales family: mycobacteriaceae genus: mycobacterium species: m. gastri binomial name mycobacterium gastriwayne 1966, atcc 15754 description moderately long to long, gram-positive, aerobic, nonmotile and acid-fast rods. colony characteristics nonchromogenic, smooth to rough, white colonies on löwenstein-jensen medium and smooth or somewhat granular on middlebrook 7h10 agar. physiology growth on löwenstein-jensen medium or on middlebrook 7h10 agar at 37 °c, (temperature range 25 °c-40 °c), within 7 or more days. does not grow in the presence of ethambutol or isoniazid. differential characteristics closely related to m. kansasii m. gastri and m. kansasii share an identical 16s rdna sequence. species differentiation is possible by differences in the its and hsp65 sequences. m. kansasii produces a photochromogenic yellow pigment. accuprobes for m. kansasii are negative. pathogenesis casual resident of human stomachs, but not considered a cause of disease. biosafety level 1 type strain first isolated from human gastric specimen. also found in soil. strain atcc 15754 = ccug 20995 = cip 104530 = dsm 43505 = jcm 12407.