Three bacterial strains of marine origin were isolated during a screening for biosurfactants among n-alkane degrading microorganisms. One strain - identified as Alcaligenes sp. MM 1 - produced a novel glucose lipid. In the case of Arthrobacter sp. EK 1 the well-known trehalose tetraester was found as major component. From another pure culture classified as Arthrobacter sp. SI 1, extracellular emulsifying agents with properties indicating high molecular weight substances were detected. Furthermore trehalose corynomycolates were found at up to 2 g/1. The isolated biosurfactants showed good interfacial and emulsifying properties.
By aid of lipases, e.g. of Mucor miehei, in n-hexane wax esters were produced from usual primary fatty alcohols and unusual hydroxy fatty acids (in part of microbial origin). Thus, (S)-17-hydroxyoctadecanoic acid dodecyl ester and (Ri-3-hydroxy decanoic acid dodecyl ester were formed. I n measurements of the film pressure using a LANGiMUIR film balance the monolayers of both compounds indicated good stability compared to the non-hydroxy wax esters. Glycolipids de novo produced by microorganisms did not show suitable wetting properties, but they were able to lower Le surface tension of water to a higher extent than the unusual waxes.
Within a screening for biosurfactants we could isolate various n-alkanes utilizing marine bacteria which were capable of synthesizing glycolipids. One strain was identified as Arthrobacter sp. EK 1 which produced trehalose lipids. After purification by column and thick layer chromatography the main fraction, an anionic 2,3,4,2′-trehalose tetraester, was obtained. The chain lengths of fatty acids ranged from 8 up to 14, furthermore succinate could be detected. Since the place of substitution of succinate has so far not been cited in literature, a definitive structural elucidation was carried out chemically by hydroboration and by 1H, 2 D1H, 13C and 13C - 1H correlation NMR measurements. All investigations confirmed the exact position of succinate at C2 atom of trehalose. After improvement of growth conditions the production of the trehalose tetraester increased up to 4.8 g/1 during a fermentation in a 20 1 bioreactor under nitrogen limitation.
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