extracted with diethyl ether or dichloromethane and then purified using standard silica gel chromatography techniques the final product may then be recrystallised as the free acid or appropriate cationic salt alternatively antibiotic uk 61 689 may be generated from crude fermentation extracts containing uk 58 852 thus a methyl isobutylketone mibk fermentation extract is concentrated and preferably dissolved in acetonitrile water and treated with para toluenesulfonic acid the preferred acetonitrile water composition contains 5 water and the ratio of crude fermentation oil to para toluenesulfonic acid is about 9 1 these ratios are approximate and may vary according to the composition of the fermentation extract other solvent systems which may be used include methanol water but the hydrolysis may also be carried out by treating the crude mibk extract with para toluenesulfonic acid in the absence of added solvent alternative acids include mineral acids such as hydrochloric acid antibiotic uk 61 689 exhibits inhibitory action against the growth of a number of gram positive microorganisms in table i below the results of in vitro tests are summarized for this test each organism is inoculated in a series of test tubes containing nutrient medium and varying concentrations of antibiotic uk 61 689 to determine the minimal concentration of the compound in u03bcg ml which inhibits the growth of the organism over a period of 24 hours mic table i______________________________________antibacterial activityorganism strain no mic u03bcg ml______________________________________clostridium perfringens 10a006 25 10a009 3 12actinomyces pyogenes 14d002 0 39 14d008 0 39 14d011 0 39treponema hyodysenteriae 94a001 6 25 94a002 6 25 94a007 3 12 94a008 3 12______________________________________ efficacy data for antibiotic uk 61 689 and its salts against coccidial infections in chickens were obtained in the following fashion groups of 3 5 ten day old pathogen free white leghorn cockerel.