Antibiotics as a Means of Control of Bacterial Contamination of Storage Tissue Disks

Abstract

DURING the investigation of metabolism of storage tissues of higher plants, it is common to wash and aerate disks of the tissue for periods of several days or weeks. To this end, a variety of techniques has been reported, but in most cases it was not possible to impose rigorous conditions of sterility, although, in analysing the behaviour of tissues treated in this way, it is evidently necessary to ensure that the presence of micro-organisms is not a significant factor. The experimenter has usually used such criteria as retention of pigment if any, maintenance of turgor, and clarity of the suspending liquid. Recently, Bacon, MacDonald and Knight¹ have shown that these criteria may be observed even when substantial contamination of disks by bacteria has occurred, and they found that disks (1 cm diam. and 1 mm thick) of sugar beet showed the presence of about 3 × 10⁷ organisms/disk after washing for 4 days. During a programme of research into enzyme synthesis in storage tissue disks^2,3 we have found that artichoke and carrot disks become contaminated with bacteria to a similar degree, ranging from 5 × 10⁵ per disk after 24 h to 4 × 10⁷ after 3 days.