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.

Dynamic combinatorial chemistry.

https://www.massey.ac.nz/%7Eychisti/Lipases.pdf

Production, purification, characterization, and applications of lipases.

Glucose oxidase--an overview.

Biosurfactants production and possible uses in microbial enhanced oil recovery and oil pollution remediation: a review

Some engineering aspects of solid-state fermentation

Enzymatic synthesis of isoamyl acetate using immobilized lipase from Rhizomucor miehei

Enzymatic reactions in nonaqueous solvents offer new possibilities for the biotechnological production of many useful chemicals using reactions that are not feasible in aqueous media. In the recent years, the use of enzymes in nonaqueous media has found applications in organic synthesis, chiral synthesis or resolution, modification of fats and oils, synthesis of sugar-based polymers, etc. The use of lipases in esterification reactions to produce industrially important products such as emulsifiers, surfactants, wax esters, chiral molecules, biopolymers, modified fats and oils, structured lipids, and flavor esters is well documented. The interest in using lipases as biotechnological vectors for performing various reactions in both macro- and microaqueous systems has picked up tremendously during the last decade. This review covers important features of lipases and lipase-catalyzed esterification reactions including the kinetics and stability of lipases, and modeling aspects.

N. G. Karanth

Papers

Some engineering aspects of solid-state fermentation

Enzymatic synthesis of isoamyl acetate using immobilized lipase from Rhizomucor miehei

Lipases and lipase-catalyzed esterification reactions in nonaqueous media

Lipase-catalyzed synthesis of isoamyl butyrate. A kinetic study.

Optimization of isoamyl acetate production by using immobilized lipase from Mucor miehei by response surface methodology.