TEM observations of Flavobacterium columnare ALG-00-530 strain in ultrapure water. Panel A, day 1 after transfer to ultrapure water. Panel B, maintained in ultrapure water for 150 days. Arrows indicate surface blebbing (SB), membrane vesicle (MV), nucleoid (N), cell membrane (CM), outer membrane (OM), periplasmic space (PS), inclusion (I), and nucleoid compaction areas (NC). Scale bars represent 500 nm.