an improved process for isolating a83543 factors from fermentation broth in which they are produced which comprises : a ) adding an approximately equal volume of a water miscible , polar organic solvent to the fermentation broth , including the biomass thereof ; b ) separating the liquid phase of the resulting mixture from the biomass ; c ) adjusting the ph of the separated liquid phase to between about 7 and 13 ; d ) applying the separated liquid phase directly to a column of nonfunctional , macroreticular polymer ; e ) eluting the a83543 components from the column with an aqueous solution of water miscible , polar organic solvent ; and f ) collecting the fractions containing a83543 components .