Emulsifying agents from bacteria isolated during screening for cells with hydrophobic surfaces

Abstract

The culture supernatants of 126 bacterial strains isolated during screening for hydrophobic cell surfaces, were tested for the production of emulsifying agents. Forty-eight strains were found to produce effective emulsion-stabilizing substances during growth on glucose. The most effective emulsifying agents were isolated and could be divided into two chemical groups. The first group was separated from the isolated extracts by the use of thin-layer chromatography and detected as ninhydrin-negative, 4,4'-tetramethyldiamino-diphenylmethane-positive spots. The amino acid composition indicated surfactin and iturin, produced by one Bacillus species, and viscosin, produced by a Pseudomonas species. The second group was identified as polymeric substances. The chemical characterization of five polymers showed polysaccharides that were able to stabilize emulsions. From these the neutral and charged monosaccharides were determined qualitatively. The constituents of the five isolated polysaccharides were: strain 5,

Structural studies of an emulsion-stabilizing exopolysaccharide produced by an adhesive, hydrophobic Rhodococcus strain

“…The isolation (Neu & Poralla, 1987) and identification (Neu & Poralla, 1988) of Rhodococcus strain No. 33 were described previously.…”

“…Gel permeation chromatography was done using Sepharose CL 4B, with a fractionation range of 3 x 104-5 x lo6, in 0.2 M-ammonium acetate buffer. The production of antibodies against the isolated polysaccharide was described elsewhere (Neu & Poralla, 1988).…”

“…One of the isolated polymeric emulsifiers was identified as polysaccharide and further characterized. This polysaccharide revealed surface-active properties as determined by different methods (Neu & Poralla, 1988). Here we present the quantitative composition and structural studies of the emulsion-stabilizing exopolysaccharide PS-33 produced by the adhesive, hydrophobic Rhodococcus strain No.…”

“…33 (Neu & Poralla, 1988) which was isolated in an enrichment of hydrophobic bacteria from freshwater (Neu & Poralla, 1987). In this screening, bacterial strains were isolated which produced low-molecular-mass biosurfactants as well as high-molecular-mass emulsifiers .…”

Untitled

“…[22,23] Tests have shown that rhamnolipids suppress the spread of breast cancer cells. [24][25][26] Rhamnolipids in the right concentration are a hemolysin, meaning that they can break up red blood cells by lysis, destroying the blood cell wall. [27,28] Rhamnolipids have numerous applications in agriculture and farming, they are effective as a fungicide and bactericide for certain agricultural pests.…”