Biodiesel Production (FAEEs) by Heterogeneous Combi-Lipase Biocatalysts Using Wet Extracted Lipids from Microalgae

Abstract

The production of fatty acids ethyl esters (FAEEs) to be used as biodiesel from oleaginous microalgae shows great opportunities as an attractive source for the production of renewable fuels without competing with human food. To ensure the economic viability and environmental sustainability of the microbial biomass as a raw material, the integration of its production and transformation into the biorefinery concept is required. In the present work, lipids from wet Isochrysis galbana microalga were extracted with ethyl acetate with and without drying the microalgal biomass (dry and wet extraction method, respectively). Then, FAEEs were produced by lipase-catalyzed transesterification and esterification of the extracted lipids with ethanol using lipase B from Candida antarctica (CALB) and Pseudomonas cepacia (PC) lipase supported on SBA-15 mesoporous silica functionalized with amino groups. The conversion to FAEEs with CALB (97 and 85.5 mol% for dry and wet extraction, respectively) and PC (91 and 87 mol%) biocatalysts reached higher values than those obtained with commercial Novozym 435 (75 and 69.5 mol%). Due to the heterogeneous nature of the composition of microalgae lipids, mixtures with different CALB:PC biocatalyst ratio were used to improve conversion of wet-extracted lipids. The results showed that a 25:75 combi-lipase produced a significantly higher conversion to FAEEs (97.2 mol%) than those produced by each biocatalyst independently from wet-extracted lipids and similar ones than those obtained by each lipase from the dry extraction method. Therefore, that optimized combi-lipase biocatalyst, along with achieving the highest conversion to FAEEs, would allow improving viability of a biorefinery since biodiesel production could be performed without the energy-intensive step of biomass drying.

Improving the Yields and Reaction Rate in the Ethanolysis of Soybean Oil by Using Mixtures of Lipase CLEAs

“…After a 48-h reaction, TLL CLEA (6000 T/g oil) gave a FAEE yield of 87 wt.%, while the mixture of both CLEAs gave a FAEE mass yield of 94 wt.%. That is, the simultaneous use of CLEAs of TLL and PPL permitted to increase the reaction rate and final yields, even though PPL CLEA give lower yields and reaction rates than TLL CLEA, as has been described in other papers that show the advantages of a mixture of lipases in this reaction [14,15,16,17,18,19,20,21,22,23,24,25,28]. In the case of a mix of PPL and TLL, the synergistic effect could be explained because PPL may exhibit higher activity versus some glycerol-linked carboxylic acids [64] that may behave as inhibitors for TLL, contributing to higher reaction rates.…”

“…Due to the heterogeneity of oils and fats, the use of a mixture of two or more lipases with different specificities has proved to be advantageous in the production of biodiesel. Several mixtures of lipases (mainly 1,3-especific and non-specific) have been reported as biocatalysts in biodiesel production, showing higher yields than those achieved using individual lipases [14,15,16,17,18,19,20,21], such as Lipozyme TL-IM and Novozym 435 in the methanolysis of rapeseed oil [22] and lard [23], lipases from Rhizopus oryzae and Candida rugosa immobilized on silica gel to catalyze the methanolysis of soybean [24,25,26] and canola oils [27], and 1,3-specific lipases from Thermomyces lanuginosus (immobilized in Lewatit VP OC 1600) and Rhizomucor miehei (commercial immobilized form, Lipozyme RM-IM) to catalyze the ethanolysis of soybean oil [28]. Even recently, it has been shown that a mixture of the same lipase immobilized following different protocols (this may alter the lipase specificity [29]) improves the final biodiesel yields [30].…”

Lipase of Pseudomonas guariconesis as an additive in laundry detergents and transesterification biocatalysts

“…Lipase enzyme from Pseudomonas cepacia has been reported for biodiesel production via transesterification reaction . The transesterification efficiency of P. guariconesis lipase was also found to be better as compared with lipases from Pseudomonas BUP6 and comparable with other lipases from P. cepacia and Candida antarctica , which were the reported lipases with transesterification properties . The enzyme showed better stability in the presence of organic solvents like methanol and ethanol, which are the commonly used solvents for transesterification.…”

Multi-Combilipases: Co-Immobilizing Lipases with Very Different Stabilities Combining Immobilization via Interfacial Activation and Ion Exchange. The Reuse of the Most Stable Co-Immobilized Enzymes after Inactivation of the Least Stable Ones

“…Thus, the interest of combilipases is clear. Moreover, in some cases, co-immobilized lipases have been used in these processes [59][60][61][62][63][64]. However, if the objective of the lipases is a single selective or specific modification of a substrate, the mixture of different lipases, with different selectivities and specificities, will decrease the performance, in these cases a lipase as pure as possible will be recommended.…”