Succinoyl trehalose lipid induced differentiation of human monocytoid leukemic cell line U937 into monocyte-macrophages

Synthesis of trehalose glycolipids

Chemical synthesis of trehalose glycolipids such as DAT, TDM, SL-1, SL-3, and Ac₂SGL from MTb, emmyguyacins from fungi, succinoyl trehalose from rhodococcus, and maradolipids from worms, as well as mycobacterial oligosaccharides is reviewed.

Simple glycolipids of microbes: Chemistry, biological activity and metabolic engineering

Glycosylated lipids (GLs) are added-value lipid derivatives of great potential. Besides their interesting surface activities that qualify many of them to act as excellent ecological detergents, they have diverse biological activities with promising biomedical and cosmeceutical applications. Glycolipids, especially those of microbial origin, have interesting antimicrobial, anticancer, antiparasitic as well as immunomodulatory activities. Nonetheless, GLs are hardly accessing the market because of their high cost of production. We believe that experience of metabolic engineering (ME) of microbial lipids for biofuel production can now be harnessed towards a successful synthesis of microbial GLs for biomedical and other applications. This review presents chemical groups of bacterial and fungal GLs, their biological activities, their general biosynthetic pathways and an insight on ME strategies for their production.

Production and Biomedical Applications of Probiotic Biosurfactants

Biosurfactants have been widely used for environmental and industrial applications. However, their use in medical field is still limited. Probiotic biosurfactants possess an immense antimicrobial, anti-adhesive, antitumor, and antibiofilm potential. Moreover, they have an additional advantage over conventional microbial surfactants because probiotics are an integral part of normal human microflora and their biosurfactants are innocuous to human. So, they can be effectively exploited for medicinal use. Present review is aimed to discourse the production and biomedical applications of probiotic biosurfactants.

Genome Sequence of Rhodococcus sp. Strain PML026, a Trehalolipid Biosurfactant Producer and Biodegrader of Oil and Alkanes

Rhodococcus sp. strain PML026 produces an array of trehalolipid biosurfactant compounds in order to utilize hydrophobic carbon sources, such as oils and alkanes. Here, we report the high-quality draft genome sequence of this strain, which has a total length of 5,168,404 bp containing 4,835 protein-coding sequences, 12 rRNAs, and 45 tRNAs.

Trehalolipid biosurfactants from nonpathogenic Rhodococcus actinobacteria with diverse immunomodulatory activities

Actinobacteria of the genus Rhodococcus produce trehalolipid biosurfactants with versatile biochemical properties and low toxicity. In recent years, these biosurfactants are increasingly studied as possible biomedical agents with expressed immunological activities. Applications of trehalolipids from Rhodococcus, predominantly cell-bound, in biomedicine are also attractive because their cost drawback could be less significant for high-value products. The review summarizes recent findings in immunomodulatory activities of trehalolipid biosurfactants from nonpathogenic Rhodococcus and related actinobacteria and compares their biomedical potential with well-known immunomodifying properties of trehalose dimycolates from Mycobacterium tuberculosis. Molecular mechanisms of trehalolipid interactions with immunocompetent cells are also discussed.

Effects of biosurfactants on the viability and proliferation of human breast cancer cells

Biosurfactants are molecules with surface activity produced by microorganisms that can be used in many biomedical applications. The anti-tumour potential of these molecules is being studied, although results are still scarce and few data are available regarding the mechanisms underlying such activity. In this work, the anti-tumour activity of a surfactin produced by Bacillus subtilis 573 and a glycoprotein (BioEG) produced by Lactobacillus paracasei subsp. paracasei A20 was evaluated. Both biosurfactants were tested against two breast cancer cell lines, T47D and MDA-MB-231, and a non-tumour fibroblast cell line (MC-3 T3-E1), specifically regarding cell viability and proliferation. Surfactin was found to decrease viability of both breast cancer cell lines studied. A 24 h exposure to 0.05 g l(-1) surfactin led to inhibition of cell proliferation as shown by cell cycle arrest at G1 phase. Similarly, exposure of cells to 0.15 g l(-1) BioEG for 48 h decreased cancer cells' viability, without affecting normal fibroblasts. Moreover, BioEG induced the cell cycle arrest at G1 for both breast cancer cell lines. The biosurfactant BioEG was shown to be more active than surfactin against the studied breast cancer cells. The results gathered in this work are very promising regarding the biosurfactants potential for breast cancer treatment and encourage further work with the BioEG glycoprotein.

Interactions of a bacterial trehalose lipid with phosphatidylglycerol membranes at low ionic strength

Trehalose lipids are bacterial biosurfactants which present interesting physicochemical and biological properties. These glycolipids have a number of different commercial applications and there is an increasing interest in their use as therapeutic agents. The amphiphilic nature of trehalose lipids points to the membrane as their hypothetical site of action and therefore the study of the interaction between these biosurfactants and biological membranes is critical. In this study, we examine the interactions between a trehalose lipid (TL) from Rhodococcus sp. and dimyristoylphosphatidylglycerol (DMPG) membranes at low ionic strength, by means of differential scanning calorimetry, light scattering, fluorescence polarization and infrared spectroscopy. We describe that there are extensive interactions between TL and DMPG involving the perturbation of the thermotropic intermediate phase of the phospholipid, the destabilization and shifting of the DMPG gel to liquid crystalline phase transition to lower temperatures, the perturbation of the sample transparency, and the modification of the order of the phospholipid palisade in the gel phase. We also report an increase of fluidity of the phosphatidylglycerol acyl chains and dehydration of the interfacial region of the bilayer. These changes would increase the monolayer negative spontaneous curvature of the phospholipid explaining the destabilizing effect on the intermediate state exerted by this biosurfactant. The observations contribute to get insight into the biological mechanism of action of the biosurfactant and help to understand the properties of the intermediate phase display by DMPG at low ionic strength.

Potential therapeutic applications of biosurfactants

Biosurfactants have recently emerged as promising molecules for their structural novelty, versatility, and diverse properties that are potentially useful for many therapeutic applications. Mainly due to their surface activity, these molecules interact with cell membranes of several organisms and/or with the surrounding environments, and thus can be viewed as potential cancer therapeutics or as constituents of drug delivery systems. Some types of microbial surfactants, such as lipopeptides and glycolipids, have been shown to selectively inhibit the proliferation of cancer cells and to disrupt cell membranes causing their lysis through apoptosis pathways. Moreover, biosurfactants as drug delivery vehicles offer commercially attractive and scientifically novel applications. This review covers the current state-of-the-art in biosurfactant research for therapeutic purposes, providing new directions towards the discovery and development of molecules with novel structures and diverse functions for advanced applications.

Production and characterization of a trehalolipid biosurfactant produced by the novel marine bacterium Rhodococcus sp., strain PML026

AIMS

The aim of this study was to evaluate biosurfactant production by a novel marine Rhodococcus sp., strain PML026 and characterize the chemical nature and properties of the biosurfactant.

METHODS AND RESULTS

A novel marine bacterium (Rhodococcus species; strain PML026) was shown to produce biosurfactant in the presence of hydrophobic substrate (sunflower oil). Biosurfactant production (identified as a trehalolipid) was monitored in whole-batch cultures (oil layer and aqueous phase), aqueous phase (no oil layer) and filtered (0·2 μm) aqueous phase (no oil or cells; extracellular) and was shown to be closely associated with growth/biomass production. Extracellular trehalolipid levels increased postonset of stationary growth phase. Purified trehalolipid was able to reduce the surface tension of water to 29 mN m(-1) at Critical Micellar Concentration (CMC) of c. 250 mg l(-1) and produced emulsions that were stable to a wide range of conditions (pH 2-10, temperatures of 20-100°C and NaCl concentrations of 5-25% w/v). Separate chemical analyses of the intact trehalolipid and its constituents demonstrated the compound was in fact a mixture of homologues (>1180 MW) consisting of a trehalose moiety esterified to a series of straight chain and hydroxylated fatty acids.

CONCLUSIONS

The trehalolipid biosurfactant produced by the novel marine strain Rhodococcus sp. PML026 was characterized and exhibited high surfactant activity under a wide range of conditions.

SIGNIFICANCE AND IMPACT OF STUDY

Strain PML026 of Rhodococcus sp. is a potential candidate for bioremediation or biosurfactant production for various applications.

Effects of a bacterial trehalose lipid on phosphatidylglycerol membranes

Bacterial trehalose lipids are biosurfactants with potential application in the biomedical/healthcare industry due to their interesting biological properties. Given the amphiphilic nature of trehalose lipids, the understanding of the molecular mechanism of their biological action requires that the interaction between biosurfactant and membranes is known. In this study we examine the interactions between a trehalose lipid from Rhodococcus sp. and dimyristoylphosphatidylglycerol membranes by means of differential scanning calorimetry, X-ray diffraction, infrared spectroscopy and fluorescence polarization. We report that there are extensive interactions between trehalose lipid and dimyristoylphosphatidylglycerol involving the perturbation of the thermotropic gel to liquid-crystalline phase transition of the phospholipid, the increase of fluidity of the phosphatidylglycerol acyl chains and dehydration of the interfacial region of the bilayer, and the modulation of the order of the phospholipid bilayer. The observations are interpreted in terms of structural perturbations affecting the function of the membrane that might underline the biological actions of the trehalose lipid.

Interactions of a bacterial biosurfactant trehalose lipid with phosphatidylserine membranes

Trehalose lipids are biosurfactants produced by rhodococci that, in addition to their well known potential industrial and environmental uses, are gaining interest in their use as therapeutic agents. The study of the interaction of biosurfactants with membranes is important in order to understand the molecular mechanism of their biological actions. In this work we look into the interactions of a bacterial trehalose lipid produced by Rhodococcus sp. with dimyristoylphosphatidylserine membranes by using differential scanning calorimetry, X-ray diffraction and infrared spectroscopy. Differential scanning calorimetry and X-ray diffraction show that trehalose lipid broadens and shifts the phospholipid gel to liquid-crystalline phase transition to lower temperatures, does not modify the macroscopic bilayer organization and presents good miscibility both in the gel and the liquid-crystalline phases. Infrared experiments show that trehalose lipid increases the fluidity of the phosphatidylserine acyl chains, changed the local environment of the polar head group, and decreased the hydration of the interfacial region of the bilayer. Trehalose lipid was also able to affect the thermotropic transition of dimyristoylphosphatidyserine in the presence of calcium. These results support the idea that trehalose lipid incorporates into the phosphatidylserine bilayers and produces structural perturbations which might affect the function of the membrane.

Interactions of a Rhodococcus sp. biosurfactant trehalose lipid with phosphatidylethanolamine membranes

Trehalose lipids are an important group of glycolipid biosurfasctants mainly produced by rhodococci. Beside their known industrial applications, there is an increasing interest in the use of these biosurfactants as therapeutic agents. We have purified a trehalose lipid from Rhodococcus sp. and made a detailed study of the effect of the glycolipid on the thermotropic and structural properties of phosphatidylethanolamine membranes of different chain length and saturation, using differential scanning calorimetry, small and wide angle X-ray diffraction and infrared spectroscopy. It has been found that trehalose lipid affects the gel to liquid crystalline phase transition of phosphatidylethanolamines, broadening and shifting the transition to lower temperatures. Trehalose lipid does not modify the macroscopic bilayer organization of saturated phosphatidylethanolamines and presents good miscibility both in the gel and the liquid crystalline phases. Infrared experiments evidenced an increase of the hydrocarbon chain conformational disorder and an important dehydrating effect of the interfacial region of the saturated phosphatidylethanolamines. Trehalose lipid, when incorporated into dielaidoylphosphatidylethanolamine, greatly promotes the formation of the inverted hexagonal HII phase. These results support the idea that trehalose lipid incorporates into the phosphatidylethanolamine bilayers and produces structural perturbations which might affect the function of the membrane.

Identification of novel small-molecule histone deacetylase inhibitors by medium-throughput screening using a fluorigenic assay

HDACs (histone deacetylases) are considered to be among the most important enzymes that regulate gene expression in eukaryotic cells. In general, increased levels of histone acetylation are associated with increased transcriptional activity, whereas decreased levels are linked to repression of gene expression. HDACs associate with a number of cellular oncogenes and tumour-suppressor genes, leading to an aberrant recruitment of HDAC activity, which results in changes of gene expression, impaired differentiation and excessive proliferation of tumour cells. Therefore HDAC inhibitors are efficient anti-proliferative agents in both in vitro and in vivo pre-clinical models of cancer, making them promising anticancer therapeutics. In the present paper, we present the results of a medium-throughput screening programme aiming at the identification of novel HDAC inhibitors using HDAH (HDAC-like amidohydrolase) from Bordetella or Alcaligenes strain FB188 as a model enzyme. Within a library of 3719 compounds, several new classes of HDAC inhibitor were identified. Among these hit compounds, there were also potent inhibitors of eukaryotic HDACs, as demonstrated by an increase in histone H4 acetylation, accompanied by a decrease in tumour cell metabolism in both SHEP neuroblastoma and T24 bladder carcinoma cells. In conclusion, screening of a compound library using FB188 HDAH as model enzyme identified several promising new lead structures for further development.

Phagocytosis of mycobacteria by U937 cells: a rapid method for monitoring uptake and separating phagocytosed and free bacteria by magnetic beads

A human-derived monocytic cell line (U937) was induced to phagocytose Mycobacterium phlei by the addition of phorbol myristate acetate (PMA) to the culture medium for 50-60 h. Cells not treated with PMA were unable to phagocytose M. phlei. Magnetic beads enabled a rapid and highly efficient separation of phagocytosed and free bacteria to be achieved, an approach which is particularly useful if colony plating is used to enumerate bacterial survival within phagocytic cells. Fluorescence-activated cell sorting (FACS) analysis showed that 98% of U937 cells contained viable bacteria after 3 h.