Application of Yeast Hydrolysate in Extracellular Lipase Production by Geotrichum candidum in Shaken Flasks, Stirred Tank, and Airlift Reactors

Abstract

Lipase production by Geotrichum candidum NRRL Y-552 was studied using an alternative nitrogen source, yeast hydrolysate (Prodex-lac 1 ), and soybean oil as the carbon source and inducer of lipase production. Factorial design and response surface methodologies were applied to obtain optimized conditions for lipase production in shaken flasks, defined as: 3.5 g/100 mL of yeast hydrolysate and 0.7 g/100 mL of soybean oil with an initial pH of 7.0 at 30 8C and 250 rpm. The resulting lipase activity after 48 h was 24.3 U/mL (0.506 U/mL . h), 52 % higher than with peptone under the same conditions (U ¼ the amount of enzyme required to liberate 1 mmol of fatty acid per minute). Lipase production with the optimized medium was conducted in a stirred tank reactor and in an airlift bioreactor, both at 30 8C and 300 rpm; the best results obtained were 15.4 U/mL after 32 h of fermentation (0.481 U/mL.h) and 19.24 U/mL after 32 h of fermentation (0.601 U/mL . h) at 1 vvm, respectively. The results presented here from both bioreactors showed similar results to a previous study with the same microorganism under the same conditions using peptone as a nitrogen source. In addition, yeast hydrolysate is a cheaper nitrogen source than peptone and yeast extract, which permits a cost reduction above 90 % under similar conditions.

A Review on Geotrichum Lipases: Production, Purification, Immobilization and Applications

“…The reduction in size of the inoculum by 10 to 2 % v/v also increased the maximum lipase activity 59 . This technique was applied with success in other studies with G. candidum and G. sp [52][53][54][60][61][62] and it was verified that the lower quantity of solid inoculum increases the lipase activity. The reduction in the quantity of inoculum probably reduced the crowding effect (a typical mycological phenomenon that causes self-inhibition in spore fungus germination under crowded conditions).…”

“…They have been used to replace the traditional nitrogen sources, maintaining or increasing lipase activity from Geotrichum. The used quantity of these sources varies greatly (3.0 -15.0 % w/w) according to the substrate and fermentation conditions 53,54,56,60,62,64 . These agro-industrial residues present a certain quantity of salts and their use eliminated the necessity of supplementing the medium with inorganic salts.…”

“…Soybean oil also shows similar results due to its similar composition to olive oil, and its low cost is a strong appeal for its application. Concentrations of 1.0 % w/w are frequently utilized, but optimized studies showed that lower concentrations (0.5 to 0.7 % w/w) are enough to induce the lipase production, and concentrations above 1.0 % w/w do not have significant effects on the increase in lipase activity [52][53][54]56,[60][61][62] . Glucose is the most used carbon source for the growth of G. candidum and the utilized concentration is usually 1.0 % w/w.…”

“…A similar technique for sampling solid cultures of G. candidum and P. camembertii was applied by Aldarf et al 50 In relation to the bioreactor choice, several studies have been conducted in shaken flasks (Table 1), but other types of bioreactors have also been applied successfully for Geotrichum cultivation; in general, the scale up from shaken flasks to a bioreactor system requires optimized cultivation conditions that can be achieved with the factorial designs methods 49,[51][52][53][54]65 . The air lift bioreactor was successfully applied for lipase production from Geotrichum because the absence of mechanical agitation reduces the damage in the mycelium and provides better conditions for obtaining high lipase activity 52,53,60 . The use of a low rate of aeration also contributes to increasing lipase activity since G. candidum grows well with low levels of oxygen 25 .…”

Enzymatic activity of a novel halotolerant lipase from Haloarcula hispanica 2TK2

“…They hydrolyze triacylglycerides into fatty acids and glycerol on an oil-water interface. Additionally they can catalyze esterifi cation, interesterifi cation, and transesterifi cation of fatty acids 1, 2 . Therefore, lipases can be used in various industrial processes such as pharmaceutical, detergents, cosmetic, food, textile, hide and leather industries, pulp and paper industries, biodegradation of plastics, wastewater treatment, production of optically active compounds and production of biodiesel 1- 3 .…”