Physical and Chemical Lipase Adsorption on SBA‐15: Effect of Different Interactions on Enzyme Loading and Catalytic Performance

Abstract

Immobilization of Pseudomonas fluorescens lipase (Pfl) on the chemically modified, or unmodified, surface of SBA‐15 mesoporous silica has been achieved. X‐ray diffraction (XRD), transmission electron microscopy (TEM), and N2 physisorption are used to monitor the effect of surface functionalization on the structural and textural features of the SBA‐15 silica support. The enzyme loading strongly depends on the type of enzyme–support interaction, the maximal loading of the chemisorbed lipase being about twice that of the physisorbed (502 and 256 mgprotein ${{\rm g}{{- 1\hfill \atop {\rm support}\hfill}}}$ respectively). The resulting biocatalysts, regardless of the different loading, are tested with a hydrolytic catalytic assay. Despite the lower loading, the physically immobilized Pfl is more active than that which is chemically immobilized. Both biocatalysts are also active in a green process for biodiesel production, leading to almost full conversion of sunflower oil and ethanol into the corresponding ethyl esters after about 7 h at 30 °C, atmospheric pressure, and in solvent‐free conditions. Recycling experiments showed that the chemically immobilized Pfl was still active after twenty reaction cycles whereas the physically immobilized Pfl lost its activity after the tenth cycle.

Enzyme immobilization by adsorption: a review

“…Silicas of different dispersive-morphological parameters and porous structures have been proposed. A representative silica used for the enzyme immobilization on a large scale is mesoporous silica SBA-15 (Santa Barbara Amorphous) with hexagonal array of pores (Salis et al 2010;Thorn et al 2011). It is characterized by small pores, from 5 to about 30 nm in diameter and a hexagonal array of pores (Grudzień et al, 2006;2007;Hartmann and Kostrov 2013).…”

“…Lipases catalyse the hydrolysis of esters formed by short-and long-chain alcohols, mono-and multi-hydroxides, and saturated and unsaturated carboxylic acids of short and long chains. The catalysts based on lipases are used in the reactions of esterification or transesterification of different substrates (Brem et al 2011;Liu et al 2013;Yu and Fang 2013), and in the process of biodiesel production (Salis et al 2010;Mendes et al 2011;Tran et al 2012). A wide use of this group of proteins and their affinity to many carriers permit their immobilization on many organic and inorganic carriers.…”

Effect of electrolytes on proteins physisorption on ordered mesoporous silica materials

“…Therefore intense research efforts to use OMS as carriers for enzymes and therapeutic proteins to obtain either stable biocatalysts or efficient drug delivery systems are expanding [13][14][15][16][17][18]. For example we found that the biocatalysts obtained using Pseudomonas Page 6 of 39 A c c e p t e d M a n u s c r i p t 5 fluorescens lipase adsorbed on mesoporous silica (SBA-15 and MSE) have a very good performance in terms of transesterification activity and recycling towards sunflower oil for the production of biodiesel [19,20]. On the other hand, silica based ordered mesoporous materials can also be considered for the physical adsorption of therapeutic biomolecules as a consequence of the relatively good biocompatibility of silica materials [21].…”

“…Indeed, a covalently attached therapeutic protein will not be easily released from the support. On the contrary, chemical binding may be an important option for biocatalysis since covalently attached enzymes are usually more stable than those physically adsorbed [20] Remarkably, during the covalent binding a structural distortion of the enzyme may occur with the partial loss of the biological activity. This is the reason why physical adsorption is also important in biocatalytic purposes (only a minimal loss of enzyme activity generally occurs), and becomes particularly competitive for the use of immobilized enzymes in non conventional (organic) media [46,47].…”

Improved Performance of Pseudomonas fluorescens lipase by covalent immobilization onto Amberzyme

“…The lipase from Pseudomonas fluorescens is a very interesting heat-resistant biocatalyst that is currently employed in many esterification and transesterification reactions [8]. The methods already used for the immobilization of Pseudomonas fluorescens lipase include physical adsorption [9], chemical adsorption [10], entrapment [11], sol-gel encapsulation [12] and covalent attachment [13]. Although the activity of covalently-immobilized enzymes is generally lower than the activity of the soluble enzymes, it was for instance reported that covalent immobilization onto Eupergit C resulted in a higher activity than the activity of soluble enzymes [14].…”