Production of Lipase from Geotrichum candidum Using Corn Steep Liquor in Different Bioreactors

Abstract

The production of an extracellular lipase using corn steep liquor (CSL) as the nitrogen source in the cultivation of Geotrichum candidum NRRLY‐552 was evaluated. The optimized conditions in shake flasks were CSL, 8.0 % w/v, soybean oil, 0.6 % w/v, pH 7.0, 30 °C, 250 rpm, and 48 h, resulting in a maximum lipase productivity of 0.438 U mL−1 h−1(U = the amount of enzyme required to liberate 1 μmol of fatty acid per minute). Scale‐up was evaluated with airlift and stirred tank reactors; the best conditions, respectively, were 1 vvm(volume of gas per volume of medium per minute) of aeration which resulted in 0.535 U mL−1 h−1 (32 h) and 1 vvm and 300 rpm resulting in 0.563 U mL−1 h−1 (16 h). To facilitate downstream processes, lipase production was also evaluated using CSL previously clarified with activated charcoal resulting in 0.275 U mL−1 h−1 (24 h) using 12 % (w/v) of clarified CSL in shake flasks. The obtained results showed that CSL leads to similar productivity compared to peptone using the same microorganism under similar conditions. In addition the cost of fermentation medium using CSL is much lower because it is a very inexpensive by‐product from corn processing.

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.…”

“…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). 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 . Studies in stirred tank bioreactor indicated that aeration of 1.0 vvm or lower are the best conditions for lipase production from Geotrichum candidum [51][52][53]60 . The low level of oxygen is also efficient in shaken flasks; several studies have indicated agitation conditions below 200 rpm for lipase production from Geotrichum, which reduces the quantity of dissolved oxygen 46,47,54,56,[62][63][64] .…”