Abstract

Lipases are an important group of enzymes with various applications in the food, chemical and pharmaceutical industry, besides having great interest for the treatment of effluents with high lipid content. The objective of this study was to isolate, characterize and select lipolytic bacteria that produce lipase from aqueous waste effluents and to study the enzymatic activity kinetics of the extract obtained via submerged fermentation. The results obtained are promising, being possible to isolate and characterize 23 lipase-producing microorganisms, mostly gram-positive bacteria, but after the fermentation step in a liquid medium, gram negative bacteria showed the highest enzymatic activity (56.72 U.L-1 for STP 2A` bacterium and 81.99 U.L-1 for R2B). In the enzymatic activity kinetic study with the selected bacterium (R2B), among the six variables (temperature, pH, minimal mineral medium, soybean oil, glucose and sodium nitrate), temperature was the one that most positively influenced the enzymatic activity, and the best results were obtained at 40°C. It was concluded that the enzyme extract obtained from environmental waste may be used to treat the effluent and contribute to reduce environmental impacts.

Highlights

  • Lipases are water-soluble enzymes that catalyze the hydrolysis of ester bonds of insoluble triacylglycerols, releasing free fatty acids, mono-or diacylglycerolin into the oil-water interface (Treichel et al, 2010)

  • The effluents used for the isolation of lipolytic bacteria were collected in 1 L bottles properly sterilized in the local Sewage Treatment Plant (STP) in two distinct points: grease trap and anaerobic treatment tank, and in the residential grease trap, both of Goiânia – GO, Brazil

  • The characterization results revealed that the majority of bacteria from aqueous waste was classified as Gram positive, and only four were classified as Gram negative (STP 2A’, T1A, R1B’ and R2B)

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Summary

Introduction

Lipases (triacylglycerol acylhydrolases, EC3.1.1.3) are water-soluble enzymes that catalyze the hydrolysis of ester bonds of insoluble triacylglycerols, releasing free fatty acids, mono-or diacylglycerolin into the oil-water interface (Treichel et al, 2010). These enzymes catalyze a wide range of reactions such as hydrolysis, esterification, trans-esterification, alcoholysis, acidolysis and aminolysis (Joseph; Ramteke; Thomas, 2008), and may be of animal, microbial or plant origin, with variations in catalytic properties, and can be obtained by solid-state fermentation or submerged fermentation (Annibale et al, 2006; Rigo et al, 2010; Papagora; Roukas; Kotzekidou, 2013). Agrotec., Lavras, v.38, n.6, p.562-572, nov./dez., 2014

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