Inositol phospholipids and cell surface receptor function.

Many microorganisms, especially bacteria, produce biosurfactants when grown on water-immiscible substrates. Biosurfactants are more effective, selective, environmentally friendly, and stable than many synthetic surfactants. Most common biosurfactants are glycolipids in which carbohydrates are attached to a long-chain aliphatic acid, while others, like lipopeptides, lipoproteins, and heteropolysaccharides, are more complex. Rapid and reliable methods for screening and selection of biosurfactant-producing microorganisms and evaluation of their activity have been developed. Genes involved in rhamnolipid synthesis (rhlAB) and regulation (rhlI and rhlR) in Pseudomonas aeruginosa are characterized, and expression of rhlAB in heterologous hosts is discussed. Genes for surfactin production (sfp, srfA, and comA) in Bacillus spp. are also characterized. Fermentative production of biosurfactants depends primarily on the microbial strain, source of carbon and nitrogen, pH, temperature, and concentration of oxygen and metal ions. Addition of water-immiscible substrates to media and nitrogen and iron limitations in the media result in an overproduction of some biosurfactants. Other important advances are the use of water-soluble substrates and agroindustrial wastes for production, development of continuous recovery processes, and production through biotransformation. Commercialization of biosurfactants in the cosmetic, food, health care, pulp- and paper-processing, coal, ceramic, and metal industries has been proposed. However, the most promising applications are cleaning of oil-contaminated tankers, oil spill management, transportation of heavy crude oil, enhanced oil recovery, recovery of crude oil from sludge, and bioremediation of sites contaminated with hydrocarbons, heavy metals, and other pollutants. Perspectives for future research and applications are also discussed.

Microbial production of surfactants and their commercial potential.

Various extracellular informational signals such as those from a group of hormones and some neurotransmitters appear to be passed from the cell surface into the cell interior by two routes, protein kinase C activation and Ca2+ mobilization. Both routes usually become available as the result of an interaction of a single ligand and a receptor and act synergistically to evoke subsequent cellular responses such as release reactions. The signal-dependent breakdown of inositol phospholipids, particularly phosphatidylinositol bisphosphate, now appears to be a key event for initiating these processes.

https://science.sciencemag.org/content/sci/225/4668/1365.full.pdf

Turnover of inositol phospholipids and signal transduction

The discovery that breakdown products of cellular sphingolipids are biologically active has generated interest in the role of these molecules in cell physiology and pathology. Sphingolipid breakdown products, sphingosine and lysosphingolipids, inhibit protein kinase C, a pivotal enzyme in cell regulation and signal transduction. Sphingolipids and lysosphingolipids affect significant cellular responses and exhibit antitumor promoter activities in various mammalian cells. These molecules may function as endogenous modulators of cell function and possibly as second messengers.

https://science.sciencemag.org/content/sci/243/4890/500.full.pdf

Functions of sphingolipids and sphingolipid breakdown products in cellular regulation

Glycosylated forms of phosphatidylinositol, which have only recently been described in eukaryotic organisms, are now known to play important roles in biological membrane function. These molecules can serve as the sole means by which particular cell-surface proteins are anchored to the membrane. Lipids with similar structures may also be involved in signal transduction mechanisms for the hormone insulin. The utilization of this novel class of lipid molecules for these two distinct functions suggests new mechanisms for the regulation of proteins in biological membranes.

https://science.sciencemag.org/content/sci/239/4837/268.full.pdf

Structural and Functional Roles of Glycosyl-Phosphatidylinositol in Membranes

Regional distribution of polyphosphoinositides in rat brain.

Rhamnose and rhamnolipide biosynthesis by Pseudomonas aeruginosa.

The biosynthesis of free and phosphatide myo-inositol from glucose by mammalian tissue slices.

A crystalline acidic glycolipide has recently will be reported later. A preliminary report of been isolated from cultures of Pseudomonas portions of this work has been published (Hauser aeruginosa by Jarvis and Johnson (1949). These and Karnovsky, 1953). authors investigated its chemical structure and found it to be composed of two moles each of MATERIS AND THODS L-rhamnose and 1-hydroxydecanoic acid linked Bacterial strain. The strain of P. aeruginosa as follows: used in these experiments was obtained from the

Studies on the production of glycolipide by Pseudomonas aeruginosa.

https://www.jbc.org/content/250/1/105.full.pdf

George Hauser

Papers

Regional distribution of polyphosphoinositides in rat brain.

Rhamnose and rhamnolipide biosynthesis by Pseudomonas aeruginosa.

The biosynthesis of free and phosphatide myo-inositol from glucose by mammalian tissue slices.

Studies on the production of glycolipide by Pseudomonas aeruginosa.

Identification of cytidine diphosphate-diglyceride in the pineal gland of the rat and its accumulation in the presence of DL-propranolol.