No abstract

No abstract

The biosynthetic origin of antibiotic A10255 was investigated using 14C-and 13C-labeled amino acids. DL-[l-13C]Serine labeled 15 of the 17 amino acid residues present in A10255G. These included the oxazole, thiazole, dehydroalanine, masked glycine, masked alanine and pyridine moieties. The same 15 residues labeled by serine were labeled by [2-13C]glycine, apparently by conversion of the glycine to [2,3-13C]serine. Formation of the pyridine ring occurred via a C3 to C3 condensation of two serines. The results indicated origin of the masked alanine from alanine; the masked glycine from glycine; the thiazole residues from cysteine; and the threonine, masked dehydrobutyrine, masked dehydronorvaline and masked dehydroleucine residues from threonine. L-[CH3-13C]Methionine labeled the methyl carbon of the masked dehydronorvaline moiety in factor B and the two methyl carbons of the masked dehydroleucine moiety in factor E. The results demonstrate that A10255 originates exclusively from amino acids in a mannersimilar to the closely related thiopeptide antibiotics nosiheptide and thiostrepton.

No abstract

A10255is a complexof new thiopeptide antibiotics produced by Streptomyces gardneri. When stirred reactors were operated in batch mode using a defined mediumwith a glucose feed, 250 /Jg/ml of A10255 were produced during a four-day fermentation cycle. The linear growth phase of S. gardneri was extended through seven days by supplementing the defined mediumwith continuous feeds of hydrolyzed casein and methyl caprate. With the supplementary feeds, antibiotic biosynthesis paralleled growth during the extended cycle and attained levels of 1 ,750 /ig/ml. Increasing the standard glucose feed rate increased titers principally by increasing cell mass. Supplementing the standard glucose feed with lipids such as caprylate or caprate, and decyl alcohol, affected cell mass minimally but produced higher titers by increasing the specific biosynthesis of A10255 per unit of biomass.