Electronic counting in growth studies of Mycobacterium avium

Metabolically uniform cells of Mycobacterium avium were obtained by selective filtration. The life cycle of these cells was followed by photomicrographs, electronic enumeration, and sizing and by viability and protein determinations. The cells elongate to form filaments several times their initial length; the increase in mass is reflected by a five- to sixfold increase of total protein in the culture. The filaments then fragment causing the production of viable coccobacilli. The techniques employed to obtain this form of growth are described and comparisons with nocardial growth are noted.