Abstract
The aim of this study was to isolate and select lipase-producing microorganisms originated from different substrates, as well as to optimize the production of microbial lipase by submerged fermentation under different nutrient conditions. Of the 40 microorganisms isolated, 39 showed a halo around the colonies and 4 were selected (Burkholderia, Bacillus sp., Penicillium lanosum and Corynebac glutamyl), where strains showing lipolytic halo Radius (R) / colony radius (r) ratio greater than 2.0 were selected. The results of submerged fermentation expressed as enzymatic activity revealed that the genera of microorganisms significantly influenced the enzymatic reaction, and lipase obtained from Burkholderia cepacia was the most promising, with activity of 0.0058 U.mL-1. It was also observed in the optimization step of lipase production that the sodium nitrate content (NaNO3) had a positive effect on enzyme production, and its increase was indicative of higher enzymatic activity. The addition of sources of organic nitrogen (corn steep liquor, p = 0.2398), carbon (soybean oil, p = 0.3379), magnesium MgSO4.7H2O (p = 0.4189) and potassium KH2PO4 (p = 0.8562) had no significant effects on the lipase production and could result in decreased production of extracellular lipases. Key words: Burkholderia cepacia, hydrolytic enzymes, residue, submerged fermentation.
Highlights
Lipases are water-soluble enzymes that catalyze the hydrolysis of ester bonds of insoluble triacylglycerols, releasing free fatty acids, mono-or diacylglycerolin the oil-water interface (Linko et al, 1998; Treichel et al, 2010)
The results of submerged fermentation expressed as enzymatic activity revealed that the genera of microorganisms significantly influenced the enzymatic reaction, and lipase obtained from Burkholderia cepacia was the most promising, with activity of 0.0058 U.mL-1
NRRL 41094, P. lanosum NRRL 3442 and C. glutamil. These results showed that there was a variation of 23.1% in the hydrolysis halos, where strain Burkholderia cepacia strain ATCC 25416 (BC25416) was the one showing the highest R/r ratio, and this difference in intensity between halos is due to the amount of extracellular lipase secreted by microorganism (Cardenas et al, 2001)
Summary
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 the oil-water interface (Linko et al, 1998; Treichel et al, 2010). Lipases may be of animal, microbial or plant origin, with variations in their catalytic properties, and can be obtained by solidstate fermentation or by submerged fermentation (Annibale et al, 2006; Rigo et al, 2010; Papagora et al, 2013). These enzymes catalyze a wide range of reactions such as hydrolysis, esterification, trans-esterification, alcoholysis, acidolysis and aminolysis (Joseph et al, 2008). The high cost of commercial enzymes makes treatment costly in the production of enzymes and in the search for new microorganisms. Some studies (Nascimento et al, 2007; Kona et al, 2001) reported the
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