A partially purified lipase produced by the thermophile Geobacillus thermoleovorans CCR11 was immobilized by adsorption on porous polypropylene (Accurel EP-100) in the presence and absence of 0.1% Triton X-100. Lipase production was induced in a 2.5% high oleic safflower oil medium and the enzyme was partially purified by diafiltration (co. 500,000 Da). Immobilization conditions were established at 25 degrees C, pH 6, and a protein concentration of 0.9 mg/mL in the presence and absence of 0.1% Triton X-100. Immobilization increased enzyme thermostability but there was no change in neither the optimum pH nor in pH resistance irrelevant to the presence of the detergent during immobilization. Immobilization with or without Triton X-100 allowed the reuse of the lipase preparation for 11 and 8 cycles, respectively. There was a significant difference between residual activity of immobilized and soluble enzyme after 36 days of storage at 4 degrees C (P < 0.05). With respect to chain length specificity, the immobilized lipase showed less activity over short chain esters than the soluble lipase. The immobilized lipase showed good resistance to desorption with phosphate buffer and NaCl; minor loses with detergents were observed (less than 50% with Triton X-100 and Tween-80), but activity was completely lost with SDS. Immobilization of G. thermoleovorans CCR11 lipase in porous polypropylene is a simple and easy method to obtain a biocatalyst with increased stability, improved performance, with the possibility for re-use, and therefore an interesting potential use in commercial conditions.

Production of recombinant thermo-alkali-stable lipase LipMatCCR11, expressed in Escherichia coli BL21 (DE3), was investigated via response surface methodology by using a face-centered design with three levels of each factor. Additionally, improvement of the catalytic performance of expressed lipase was assessed by immobilization on microporous polypropylene. Results showed that inducer (isopropyl β-d-1-thiogalactopyranoside [IPTG]) concentration and temperature were found to be the significant factors (P < 0.05). The maximum lipase expression was obtained at IPTG 0.6 mM, 16 °C, and 18 H, with a specific lipase activity of 7.29 × 10 U/mg, which was 36.4 times higher (over 1,300-fold increase) than lipase activity measured under nonoptimized conditions. On the other hand, immobilized lipase showed a high biocatalytic activity, particularly in the synthesis of aroma esters.

The recombinant lipase LipMatCCR11 from the thermophilic strain Geobacillus thermoleovorans CCR11 was applied in the synthesis of n-butyl caproate via transesterification in hexane and xylene. The short chain flavour ester was obtained by alcoholysis from ethyl caproate and n-butyl alcohol and acidolysis from n-butyl butyrate and caproic acid. This enzyme was also used in the condensation reaction from caproic acid and n-butanol. The conversion percentages at equilibrium (Xe) were similar to those obtained with Candida antarctica lipase fraction B (CAL-B) in the same reaction conditions, while lower conversion velocities (k) were attained. LipMatCCR11 reached high conversion percentages in either hexane or xylene as organic media (> 63%); the enzyme was also able to catalyze the aminolysis reaction of ethyl caproate with benzyl amine in hexane obtaining a conversion percentage > 62%.

Lipases are the versatile biological catalysts used in a wide range of commercial synthetic applications. Microbial lipases have been widely used in the pharmaceutical, food, textile, oleochemical, paper, and bioenergy industries, in the composition of detergents, and in the production of polymers and enantiomerically pure chemical intermediates. Lipases have a unique lid opening mechanism that makes them interesting biocatalysts to catalyze reactions in hydrophobic environments. Water insoluble substrates have also been efficiently transformed by lipases in organic solvents. The use of lipases in industrial processes could be limited by the cost of their production, the difficulties in their recovery and disposal, or by the harsh conditions of some processes that could inactivate or denature the protein. The immobilization of enzymes helps overcome these physical and economical drawbacks, making the catalyst more active, stable, and reusable, resulting in the reduction of costs and of contaminating and harmful byproducts. Polypropylene has unique properties that aid in the activation of the lid opening mechanism and improve the catalytic efficiency of immobilized lipases. The aim of this review is to present an overview of the uses of polypropylene as a support for immobilization of lipolytic enzymes, the study of the immobilization procedure conditions, the characteristics of the immobilized enzymes, and the perspectives of their use in the future as a powerful tool in sustainable industry.

Immobilization of enzymes has many advantages for their application in biotechnological processes. In particular, the cross-linked enzyme aggregates (CLEAs) allow the production of solid biocatalysts with a high enzymatic loading and the advantage of obtaining derivatives with high stability at low cost. The purpose of this study was to produce cross-linked enzymatic aggregates (CLEAs) of LipMatCCR11, a 43 kDa recombinant solvent-tolerant thermoalkaliphilic lipase from Geobacillus thermoleovorans CCR11. LipMatCCR11-CLEAs were prepared using (NH4)2SO4 (40% w/v) as precipitant agent and glutaraldehyde (40 mM) as cross-linker, at pH 9, 20 °C. A U10(56) uniform design was used to optimize CLEA production, varying protein concentration, ammonium sulfate %, pH, glutaraldehyde concentration, temperature, and incubation time. The synthesized CLEAs were also analyzed using scanning electron microscopy (SEM) that showed individual particles of <1 µm grouped to form a superstructure. The cross-linked aggregates showed a maximum mass activity of 7750 U/g at 40 °C and pH 8 and retained more than 20% activity at 100 °C. Greater thermostability, resistance to alkaline conditions and the presence of organic solvents, and better durability during storage were observed for LipMatCCR11-CLEAs in comparison with the soluble enzyme. LipMatCCR11-CLEAs presented good reusability by conserving 40% of their initial activity after 9 cycles of reuse.