A yeast strain, isolated from the exudate of a tree, accumulated biosurfactants abundantly when grownon soybean oil as the sole carbon source. Thebiosurfactants were found to be a mixture of 4 mannosylerythritol lipids, including two new mannosylerythritol lipids as major components. The major components, which amounted to about 80 % of the total lipids, were determined to be 4-0-(di-0-acetyl-di-O-alkanoyl-/?-D-mannopyranosyl)-erythritol and 4-0-(mono-0-acetyl-di-0-alkanoyl-/?-D-mannopyranosyl)-erythritol. The yeast strain was identified as Candida antarctica (Goto et al.) Kurtzman et al. Wepreviously reported that Candida sp. B-7 produced a mannosylerythritol lipid (MEL), that is, 4-O-(2/,6/-di-O-alkanoyl-^-D-mannopyranosyl)-erythritol (designated as MEL-B7), from /7-alkanes or vegetable oils in high concentrations (about 30g/l).1 2) We again tried to screen microorganisms accumulating biosurfactants and succeeded in obtaining some strains by using a selective medium containing soybean oil as a renewable resource. A yeast strain, T-34, was found to extracellularly accumulate anthrone-positive biosurfactants, which were a mixture of MELs showing different Rfvalues from that of MEL-B7 on thin-layer chromatography. This paper describes the screening for microorganisms accumulating biosurfactants, identification of the isolated yeast and characterization of the biosurfactants accumulated by the yeast. Materials and Methods Microorganisms. Strain T-34 used in this study was isolated from the exudate of a tree on Mt. Tsukuba.

Filamentous cyanobacteria belong to the most prolific producers of structurally unique and biologically active natural products, yet the majority of biosynthetic gene clusters predicted for these multicellular collectives are currently orphan. Here, we present a systems analysis of secondary metabolite gene expression in the model strain Nostoc punctiforme PCC73102 using RNA-seq and fluorescence reporter analysis. Our data demonstrate that the majority of the cryptic gene clusters are not silent but are expressed with regular or sporadic pattern. Cultivation of N. punctiforme using high-density fermentation overrules the spatial control and leads to a pronounced upregulation of more than 50% of biosynthetic gene clusters. Our data suggest that a combination of autocrine factors, a high CO2 level, and high light account for the upregulation of individual pathways. Our overarching study not only sheds light on the strategies of filamentous cyanobacteria to share the enormous metabolic burden connected with the production of specialized molecules but provides an avenue for the genome-based discovery of natural products in multicellular cyanobacteria as exemplified by the discovery of highly unusual variants of the tricyclic peptide microviridin.

Many strains of the genus Ustilago were found to be good producers of organic acids, that is, itaconic, /-itatartaric, /-2-hydroxyparaconic, and L-malic acids. Itatartaric and 2-hydroxyparaconic acids were invariably produced together with itaconic acid. Fromthese findings and the results of the experiments with permeabilized cells of Ustilago cynodontis, the following metabolic sequence was assumed: itaconate-*2-hydroxyparaconate-ntatartarate, as a by-path from the tricarboxylic acid cycle.