Lipid accumulation in an oleaginous yeast (Candida 107) growing on glucose in single-stage continuous culture

Lipid accumulation of Candida 107, grown at dilution rates from 0.03 to the maximum of 0.21/h, with carbon, nitrogen, phosphate, and magnesium limitations in a chemostat, was maximal at about 40% (wt/wt) with nitrogen-limited medium at a dilution rate of 0.06/h, giving an efficiency of substrate conversion of 22 g of lipid per g of glucose consumed. At higher dilution rates the lipid content decreased. With carbon-limited growth, the highest lipid content (14%, wt/wt) was at the maximum dilution rate. High lipid contents also occurred with phosphate + nitrogen as double limitations of growth, with the lipid content of the yeast (about 35%, wt/wt) continuing to be near maximum at dilution rates also near maximum (0.17/h), thus giving the highest specific rate of lipid formation of any growth conditions (0.59 g of lipid/g of yeast per h). However, the efficiency of substrate utilization was only 5.2 g of lipid formed per 100 g of glucose consumed. The composition of the fatty acyl residues within the lipid remained constant over many weeks if the steady-state conditions remained unchanged. With carbon-limited growth, the degree of unsaturation of the fatty acids markedly decreased as the dilution rate was increased, but with nitrogen limitation the reverse trend was seen. In all cases, linoleic and oleic acids were the principal fatty acyl residues affected, and their relative proportions always varied in opposite directions. When magnesium was a limiting nutrient, there was a considerable increase in the proportion of myristic acid produced within the lipid. Neutral lipids (predominantly triglycerides) varied from 66 to 92% of the total lipid from carbon- and nitrogen-limited growth; phospholipids (varying from 2 to 25%) were highest in nitrogen-limited growth. The fatty acyl residues within each lipid fraction showed the same variations with changing growth rates.

Bromomonamycins, unnatural analogues of the monamycin cyclodepsipeptide antibiotics: production, isolation, and biological activity

Growth of Streptomyces jamaicensis in a low-chloride medium supplemented with NaBr resulted in the biosynthesis of brominated analogues of the natural chlorinated monamycins. Purification of these new compounds was undertaken by Craig countercurrent distribution studies. Diffusion and dilution assays indicated that antibiotic activity of a monamycin was inversely proportional to its unsolvated molecular weight. The bromo analogues were the least active of the series.

Production of the monamycins, novel depsipeptide antibiotics

Methods are described for the production of the monamycins by Streptomyces jamaicensis in shake flasks and jar fermentors. The effects on the fermentation of variations in pH, temperature, medium composition, volume of inoculum, and strain of the organism are discussed. The methods employed for the extraction and for the microbiological assay of the antibiotics are outlined.