Study On The Precursor-directed Effect Of Lipoglycopeptide Antibiotic A40926 Production By Fermentation With Nonomuraea Sp.

A40926 is a natural lipoglycopeptide antibiotics produced by Nonomuraea sp.ATCC39727 mainly including factor A₀,A₁,B₀ and B₁.The only difference between them is the acyl chain.A40926 B₀ is the precursor for the synthesis of dalbavancin.It was assumed that the acyl moieties in A40926 derived from cellular fatty acids by shortening the carbon chains throughβ-oxidation.In this paper,the precursor-directed effect of A40926 production by fermentation with Nonomuraea sp.ATCC 39727 was studied.The composition of Nonomuraea sp.ATCC 39727 cell fatty acids was analyzed as fatty acid methyl esters derivatives（FAMEs）by GC-MS method.Twelve fatty acids were detected from Nonomuraea sp.ATCC 39727 cells,and the main components were iso-C16:0,n-C16:1^△7,n-C16:0,and n-C18:1^△9.Linear acids with an even number of carbons predominated in Nonomuraea sp.ATCC 39727 cells,but fatty acids with odd number of carbons（C15,C17）were low in content.The capability of Nonomuraea sp.ATCC 39727 using short-chain carboxylic acids as primer sources for fatty acids biosynthesis was examined.It was observed that isobutyryl-CoA,butyryl-CoA and propionyl-CoA were the preferred starter units for fatty acid biosynthesis in Nonomuraea sp.ATCC 39727,and 3-methylbutyrate was a poor substrate for the fatty acid synthase.The cellular fatty acids composition in Nonomuraea sp.ATCC 39727 mainly depended on the affinity of the starter for the fatty acid synthase.The analysis method of A40926 by HPLC was erected as follows:Hypersil C₁₈ column（4.6×250 mm）,the mobile phase of A（acetonitrile）and B（0.1%NH₄FA solution）,gradient elution,flow rate of 1.0 mL/min,injection volume of 10μL,and detection wavelength at 230nm.The reproducibility and accuracy of results are high.The relationship among branched amino acids as precursor,the composition of Nonomuraea sp.ATCC 39727 cell fatty acids and A40926 complex composition was investigated in A40926 production by fermentation.The results showed that the valine addition significantly increased iso-16:0 fatty acid ratio in Nonomuraea sp.ATCC 39727cells and resulted in factor B₀（characterized by iso-C12:0 chain）as the major component of the antibiotic complex,which indicated the precursor-directed effect of lipoglycopeptide antibiotic A40926 production by fermentation with Nonomuraea sp.ATCC 39727.