The effects of temperature (20°, 25°, 30° C), pH (7.5, 8.0, 8.5) and dissolved oxygen (40%, 45%, 50%, 55%, 60% of concentration in air-saturated medium) on the growth of Brevibacterium linens were studied with cultures on sodium l-lactate and casamino acids in a regulated fermentor, using a factorial design methodology and an analysis of variance programme. The effect on growth rates was very striking: an extremely significant quadratic effect of oxygen, a marked negative effect of pH and a great negative interaction between pH and temperature were observed. Growth, transition from cocci to rods and pigmentation were inhibited by dissolved oxygen levels of 40% and 60%, while the level 50% produced higher absorbance values and growth rates.