PROTECTIVE ACTION OF A TETRACYCLINE-SENSITIVE STRAIN OF ESCHERICHIA-COLI ON A TETRACYCLINE-RESISTANT STRAIN IN A COCULTURE GROWN IN THE PRESENCE OF THE ANTIBIOTIC

The addition of tetracycline to a culture of a tetracycline-sensitive strain of Escherichia coli leads to the appearance in the medium of a chemical compound (or compounds) that in part relieve the inhibition o f growth of a tetracycline-resistant strain by a high concentration of the antibiotic. An increase in the growth rate can be as high as 50%.