Biochemistry of the Ustilaginales: Ii. Isolation and Partial Characterization of Ustilagic Acid

Abstract

T h e neetllelilie crystals ~i~l~i c h form in aerated submergecl c u l t~~r r s of the corn sn111t Uslilngo ecae (PIZL-119) \\;ere f o~~n c l t o be a 1)-glucolipid, m.p. 14G-i0C., [a]:+ 7' (pyriclinc), \~fhich contained one carbosyl group, two ester groups, a t least two terminal methyl groups, a n d two 11-glucose resitlues per ri~ole. On t h e basis of elementary a~ialyses, neutralization equivalent, a n d molecular iveight estimations, the molecular formllla of the material isolated \\,as approsirnately CjiHG?-aOli. T h e substance \\.as not shown t o be chemically honlogeneous.Conditions ~~s e d in c u l t~~r i n g the fungus ill stirred fermcntors to produce t h e crystalline nietabolic product, which was termed "~~s t i l a g i c acid", are describetl, and a procedure for the isolation of the material is given.Haskins ( I ) has shown that tlie corn smut Lirtilago zeae (PRL-119) can clissimilatc carbolij drates rapidly in aerated s~~brncrged cultures n-ith the procluction of a substa~ice which p~-ecipitatecl in the culture mixt~lre in the form of long neecllelike crystals. Since the c u l t~~r e mixture clisplayecl PI-onouncecl antibiotic activity ( I ) , our interest in the chemical nature of the substance was aroused.T h e conclitions usecl for the cultivatio~i of the fungus ancl the production of the material investigatecl in this work are descr-ibecl in the esperimc~ltal section. -4 culture n~eclium containing D-glucose, urea, corn steep liquor, and mineral salts buffered by calcium carbonate was usecl. T h e fungus was grown sirccessfully in 30-liter stainless steel fcrmentors.Tests sho\\~ecl the crystalline material which was cleposited in tlie culture meclium to be reaclily soluble in methanol, pyridine, 2,3-b~~tanecliol, ancl 1,2-PI-opanecliol, only spal-ingly soluble in ethanol, butanol, and acetone, and insoluble in water, glycerol, ethyl acetate, cliethyl ether, benzene, and petroleum ether. These remarlcable solubility 111-operties inclicatecl that the substance was moderately polar in che~kical nature and proviclecl means for its separation from the other culture solids.

The Multifunctional β-Oxidation Enzyme Is Required for Full Symptom Development by the Biotrophic Maize Pathogen Ustilago maydis

“…We also noted that both the wild-type and mutant strains produced extracellular needle-like crystal structures in the medium with erucic acid (data not shown). These crystals could be glycolipids because U. maydis is known to produce extracellular glycolipids called ustilipids (10,29,46) that are visible as needle-like precipitates. Interestingly, similar long needle-like crystals were also observed when wild-type strains were grown in the medium supplemented with both oleic and linoleic acids but not in the medium containing either one of these fatty acids alone (data not shown).…”

The Transition from a Phytopathogenic Smut Ancestor to an Anamorphic Biocontrol Agent Deciphered by Comparative Whole-Genome Analysis

“…Cheng et al (2001) were the first to bring forth biological evidence by observing that the fungus was only amenable to genetic transformation when using promoters from U. maydis to drive expression of a selectable marker. This was followed by the discovery of an unusual glycolipid produced by P. flocculosa that was nearly identical to ustilagic acid, a rare metabolite identified in culture filtrates of U. maydis in 1951 (Lemieux et al, 1951;Mimee et al, 2005). Taking advantage of the annotated genome of U. maydis and based on specific chemical characteristics of the molecule, Bölker's group was able to find a cluster of 10 genes responsible for the synthesis of ustilagic acid in U. maydis (Teichmann et al, 2007).…”

Identification of a Gene Cluster for Biosynthesis of Mannosylerythritol Lipids in the Basidiomycetous Fungus Ustilago maydis

“…The basidiomycetous fungus Ustilago maydis is known to produce large amounts of extracellular glycolipids (1,6,23,32). U. maydis is unique among fungal producers of biosurfactants because it produces two structurally different classes of glycolipids.…”