A Highly Specific Growth-inhibitory Factor produced by Certain Acetobacter Species

Abstract

RECENT studies¹ with a cellulose-producing culture of Acetobacter acetigenum NCIB 8132 revealed that this culture contained mutant organisms which were unable to produce extracellular cellulose (celluloseless mutants). Their presence in the wild-type culture was indicated by a mass-plating technique in which a large inoculum from a cellulose-producing culture was spread on the surface of glucose (3 per cent, w./v.), ‘Difco’ yeast-extract (0.5 per cent, w./v.) (GYE) medium (_pH 7.0) containing agar (2 per cent, w./v.) ; mutant organisms showed a different colony type and a faster growth-rate than wild-type organisms. In GYE liquid medium parent organisms produced a cellulose pellicle, the medium under the pellicle remaining virtually clear. In contrast, mutant organisms grew diffusely in liquid medium and produced a moderate degree of turbidity. Despite the fact that mutant organisms could be detected in wild-type cultures by the mass-plating procedure, all our attempts to isolate mutants from cellulose-producing cultures by the indirect-select ion method of Lederberg and Lederberg² have been unsuccessful. The present work was undertaken in an attempt to clarify this contradictory behaviour.