Call number: LD2668 .T4 1957 M87 / Master of Science

The work presented in this thesis is concerned with the effect of several antibiotics and quaternary ammonium sanitizers upon growth of lactic acid bacteria. Section I reports the purification of beta-lactamase from Lactococcus cremoris PR-108, by ion exchange chromatography, using the chromogenic substrate pyridine-2-azo-p-dimethylaniline (PADAC) as the enzymatic indicator. Section II reports a study of the influence of antibiotics on lactococcal growth, where the effects of incubation time, culture dilution and the use of seeded and spread agar plate techniques are investigated. These studies were extended, in section III, to include investigations of the effect of quaternary ammonium base sanitizer (Ster-bac) on lactic starters. In addition, this section describes an reverse phase high performance liquid chromatography assay for the detection of quaternary ammonium compounds in milk. / Graduation date: 1991