The importance of rhamnolipid-biosurfactant-induced changes in bacterial membrane lipids of Bacillus subtilis for the antimicrobial activity of thiosulfonates.

The antimicrobial properties of methyl (MTS) and ethyl (ETS) esters of thiosulfonic acid alone and in combination with rhamnolipid-biosurfactant (RL) have been characterized for their ability to disrupt the normal physiological functions of living pathogens. Bactericidal and fungicidal activities of MTS and ETS and their combination with rhamnolipid were demonstrated on strains of Pseudomonas aeruginosa, Bacillus subtilis, Alcaligenes faecalis, and Rhizopus ngtricans. It was found that the combination of rhamnolipid and thiosulfonic esters has a synergistic effect leading to decreasing of bactericidal and fungicidal concentrations of MTS and ETS.

The effect of rhamnolipid biosurfactant produced by Pseudomonas fluorescens on model bacterial strains and isolates from industrial wastewater.

In this study, the effect of rhamnolipid biosurfactant produced by Pseudomonas fluorescens on bacterial strains, laboratory strains, and isolates from industrial wastewater was investigated. It was shown that biosurfactant, depending on the concentration, has a neutral or detrimental effect on the growth and protein release of model Gram (+) strain Bacillus subtilis 168. The growth and protein release of model Gram (-) strain Pseudomonas aeruginosa 1390 was not influenced by the presence of biosurfactant in the medium.

Evaluation of different carbon sources for growth and biosurfactant production by Pseudomonas fluorescens isolated from wastewaters.

The indigenous strain Pseudomonas fluorescens, isolated from industrial wastewater, was able to produce glycolipid biosurfactants from a variety of carbon sources, including hydrophilic compounds, hydrocarbons, mineral oils, and vegetable oils. Hexadecane, mineral oils, vegetable oils, and glycerol were preferred carbon sources for growth and biosurfactant production by the strain. Biosurfactant production was detected by measuring the surface and interfacial tension, rhamnose concentration and emulsifying activity.

Anti-herpesvirus activities of Pseudomonas sp. S-17 rhamnolipid and its complex with alginate.

The rhamnolipid biosurfactant PS-17 and its complex with the polysaccharide alginate, both produced by the Pseudomonas sp. S-17 strain, were studied for their antiviral activity against herpes simplex virus (HSV) types 1 and 2. They significantly inhibited the herpesvirus cytopathic effect (CPE) in the Madin-Darby bovine kidney (MDBK) cell line.

Rhamnolipid-biosurfactant permeabilizing effects on gram-positive and gram-negative bacterial strains.

The potential of biosurfactant PS to permeabilize bacterial cells of Pseudomonas aeruginosa, Escherichia coli, and Bacillus subtilis on growing (in vivo) and resting (in vitro) cells was studied. Biosurfactant was shown to have a neutral or detrimental effect on the growth of Gram-positive strains, and this was dependent on the surfactant concentration. The growth of Gram-negative strains was not influenced by the presence of biosurfactant in the media.

Effects of rhamnolipid-biosurfactant on cell surface of Pseudomonas aeruginosa.

The effect of rhamnolipid-biosurfactant produced by Pseudomonas sp. PS-17 on cell surface structures of Pseudomonas aeruginosa NBIMCC 1390 was studied. The results demonstrated that the rhamnolipid at concentrations below and above CMC provoked a multi-component response of the bacterial cells without affecting their growth and viability.

Production and properties of biosurfactants from a newly isolated Pseudomonas fluorescens HW-6 growing on hexadecane.

The newly isolated from industrial wastewater Pseudomonas fluorescens strain HW-6 produced glycolipid biosurfactants at high concentrations (1.4-2.0 g l(-1)) when grown on hexadecane as a sole carbon source.

Characterization of bacterial isolates from industrial wastewater according to probable modes of hexadecane uptake.

Bacterial isolates from industrial wastewater were characterized according to probable modes of hexadecane uptake based on data for cell surface hydrophobicity, emulsifying activity, glycoside content and surface tension of cell-free culture medium. The results obtained suggested that both modes of biosurfactant-enhanced hexadecane uptake by bacterial strains take place, direct uptake and alkane transfer. The increase in cell surface hydrophobicity and glycoside production by the strains suggested the existence of biosurfactant-enhanced interfacial uptake of the alkane.

Hydrolytic enzymes and surfactants of bacterial isolates from lubricant-contaminated wastewater.

Fifteen bacterial monocultures were isolated from lubricant-contaminated wastewater of an electric power station in Sofia. Six isolates showed best growth in liquid media with 1.5% hexadecane, and on mineral salt agar plates supplemented with one of the following hydrocarbons: n-hexadecane, paraffin, kerosene and samples of wastewater.

Biosurfactant-rhamnolipid effects on yeast cells.

Aim: The aim of this work was to study the effect of the novel surfactant PS from Pseudomonas sp. S-17 on Saccharomyces cerevisiae 83-20 yeast cells and to compare it with the effect of the well known surfactant Triton X-100.

Methods And Results: The effect of surfactants was investigated on the cells during growth, and on the separated cells.

Copper accumulation and phosphatase activities of Aspergillus and Rhizopus.

Copper accumulation and phosphatase activities of three Aspergillus species resistant to copper were compared to three copper-sensitive Rhizopus species. High level of acid phosphatases and decreased Cu2+-uptake were found with resistant in contrast to sensitive strains. The presence of copper(II) ions in the medium increased the production of acid phosphatases in the resistant A.

Phosphorylase phosphatase activity in Saccharomyces cerevisiae 257.

A phosphatase, active towards phosphorylase a and phosphorylated proteins casein and histone II-A, was isolated from Saccharomyces cerevisiae 257. The enzyme dephosphorylated glycogen phosphorylase from commercial yeast rendering it inactive. The protein phosphatase activity was not influenced by any metal ions.

Yeast permeabilization as a tool for measurement of in situ enzyme activity: localization of alkaline phosphatase.

The biochemical and ultracytochemical localization of alkaline phosphatases in permeabilized cells of Saccharomyces cerevisiae 257 has been studied. The treatment with non-ionic surfactant Triton X-100 allows the penetration of the substrate into intact yeast cells and thus provides detailed detection of the enzyme activity in ultracytochemical studies.

A specific alkaline phosphatase from Saccharomyces cerevisiae with protein phosphatase activity.

In this paper, specific PHO13 alkaline phosphatase from Saccharomyces cerevisiae was demonstrated to possess phosphoprotein phosphatase activity on the phosphoseryl proteins histone II-A and casein. The enzyme is a monomeric protein with molecular mass of 60 kDa and hydrolyzes p-nitrophenyl phosphate with maximal activity at pH 8.2 with strong dependence on Mg2+ ions and an apparent Km of 3.

Influence of growth temperature on the acid phosphatase activity in the yeast Yarrowia lipolytica.

The adaptation of the yeast Yarrowia lipolytica 76-18 to growth temperature was studied by measuring the levels of secreted and intracellular acid phosphatase activities during growth at five temperatures from 8 to 36 degrees C. The intracellular acid phosphatase activity is maximal at a growth temperature of 20 degrees C. The level of the secreted phosphatase activity decreases as growth temperature increases from 15 to 36 degrees C.

Comparison of the phosphate-repressible and-constitutive acid phosphatases of Yarrowia lipolytica.

The phosphate-repressible acid phosphatase from Yarrowia lipolytica cells was more thermostable but more sensitive to urea denaturation and to the effect of Triton X-100 than the constitutive counterpart. The K m values of the repressible and constitutive enzymes for p-nitrophenyl phosphate were 3.6 mM and 7.

Phosphatase activity during growth of Yarrowia lipolytica.

The yeast Yarrowia lipolytica produces four patterns of phosphatase activity during growth in the presence or absence of inorganic phosphate in the medium. Activities had pH optima at 4.2, 5.

Purification and partial characterization of acid phosphatase from Candida lipolytica.

Non-specific acid phosphatase from Candida lipolytica cells was purified 111-fold by chromatography on DEAE-cellulose and gel filtration on Sephadex G-100 and Sepharose 4B. The enzyme is a glycoprotein containing 67% neutral sugars. The molecular mass of the highly purified acid phosphatase was found to be approximately 95 kDa by both SDS-PAGE and gel filtration.