Bacterial lipases

Abstract

Many different bacterial species produce lipases which hydrolyze esters of glycerol with preferably long-chain fatty acids. They act at the interface generated by a hydrophobic lipid substrate in a hydrophilic aqueous medium. A characteristic property of lipases is called interfacial activation, meaning a sharp increase in lipase activity observed when the substrate starts to form an emulsion, thereby presenting to the enzyme an interfacial area. As a consequence, the kinetics of a lipase reaction do not follow the classical Michaelis-Menten model. With only a few exceptions, bacterial lipases are able to completely hydrolyze a triacylglycerol substrate although a certain preference for primary ester bonds has been observed. Numerous lipase assay methods are available using coloured or fluorescent substrates which allow spectroscopic and fluorimetric detection of lipase activity. Another important assay is based on titration of fatty acids released from the substrate. Newly developed methods allow to exactly determine lipase activity via controlled surface pressure or by means of a computer-controlled oil drop tensiometer. The synthesis and secretion of lipases by bacteria is influenced by a variety of environmental factors like ions, carbon sources, or presence of non-metabolizable polysaccharides. The secretion pathway is known for Pseudomonas lipases with P. aeruginosa lipase using a two-step mechanism and P. fluorescens lipase using a one-step mechanism. Additionally, some Pseudomonas lipases need specific chaperone-like proteins assisting their correct folding in the periplasm. These lipase-specific foldases (Lif-proteins) which show a high degree of amino acid sequence homology among different Pseudomonas species are coded for by genes located immediately downstream the lipase structural genes. A comparison of different bacterial lipases on the basis of primary structure revealed only very limited sequence homology. However, determination of the three-dimensional structure of the P. glumae lipase indicated that at least some of the bacterial lipases will presumably reveal a conserved folding pattern called the alpha/beta-hydrolase fold, which has been described for other microbial and human lipases. The catalytic site of lipases is buried inside the protein and contains a serine-protease-like catalytic triad consisting of the amino acids serine, histidine, and aspartate (or glutamate). The Ser-residue is located in a strictly conserved beta-epsilon Ser-alpha motif. The active site is covered by a lid-like alpha-helical structure which moves away upon contact of the lipase with its substrate, thereby exposing hydrophobic residues at the protein's surface mediating the contact between protein and substrate.(ABSTRACT TRUNCATED AT 400 WORDS)

Detergent compatible alkaline lipase produced by marine Bacillus smithii BTMS 11

“…Because of that, under strong acidic and alkaline conditions, enzymes are denatured and as a consequence, their activity is totally or partially lost (Chellappan 2006). A change in pH will have a progressive effect on the structure of the protein and the enzyme activity (Fullbrook 1996) and at the optimal pH, the conformation of lipase is suitable to absorb to the interface of oil/water, helping open the lid that blocks the active site of the lipase to lower the activation energy of hydrolysis (Jaeger et al 1994). Generally, bacterial lipases have neutral (Dharmsthiti and Luchai 1999;Lee et al 1999) or alkaline pH as optimum (Kanwar and Goswami 2002;Sunna et al 2002).…”

Isolation and Characterization of Lipase producing Bacteria from Vegetable Oil Spillage Site

“…Greater part of bacterial lipases comes from Gram-negative bacteria and the most important Gram-negative genus is Pseudomonas which contains at least seven lipase producing species that are P. aeruginosa, P. alcaligenes, P. fragi, P. glumae, P. cepacia, P. fluorescens and P. putida (Kojima et al, 2003). Besides Pseudomonas species Achromobacter, Alcaligenes, Burkholderia and Chromobacterium strains are the most common lipase producing gram-negatives (Gupta and Rathi, 2004 (Jaeger et al, 1994).…”

“…Bacterial lipases are mostly extracellular and are greatly influenced by nutritional and physico-chemical factors, such as temperature, pH, nitrogen and carbon sources, presence of lipids, inorganic salts, agitation and dissolved oxygen concentration (Brune and Gotz, 1992;Jaeger et al, 1994).…”

Isolation and Identification of a Novel Lipase Producing Bacteria from Oil Spilled Soil

“…After incubation the isolates were observed for lipolysis i.e zone of hydrolysis around the colony. Lipase production is indicated by the formation of clear halos around the colonies grown on tributyrin-containing agar plates [5,8].…”

“…In order to increase the cell yields and the enzymatic activities of the cells or to produce altered enzymes, genetic and environmental manipulations can be performed more readily on bacterial cells due to their short generation times, their simple nutritional needs and easy screening procedures for desired properties [4].Greater part of bacterial lipases comes from Gram-negative bacteria and the most important Gram-negative genus is Pseudomonas which contains at least seven lipase producing species, that are P.aeruginosa, P. alcaligenes, P. fragi, P. glumae, P .cepacia, P. fluorescens and P. putida [5,6]. Enzymes of P. aeruginosa, P. cepacia and P. fluorescens obtained in industrial conditions and are used in organic synthesis, including catalysis of reactions in aqueous solutions [7].…”