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An enzymatic process using a packed bed bioreactor with recirculation was developed for the scale-up synthesis of 2-ethylhexyl palmitate with a lipase fromCandidasp. 99–125 immobilized on a fabric membrane by natural attachment to the membrane surface. Esterification was effectively performed by circulating the reaction mixture between a packed bed column and a substrate container. A maximum esterification yield of 98% was obtained. Adding molecular sieves and drying the immobilized lipase both decreased the water content at the reactor outlet and around the enzyme, which led to an increase in the rate of esterification. The long-term stability of the reactor was tested by continuing the reaction for 30 batches (over 300 h) with an average esterification yield of about 95%. This immobilized lipase bioreactor is scalable and is thus suitable for industrial production of 2-ethylhexyl palmitate. [ABSTRACT FROM AUTHOR]

Abstract: Nonwoven fabrics of polypropylene (PP), polyethylene terephthalate (PET) and viscose fiber were used as novel and inexpensive support membranes for the immobilization of lipase. The use of a co-solvent during the immobilization process improved the activity of the coupled protein and the operational stability of PP and PET membranes. Covalent methods of immobilization caused the support membranes to become fragile and the lipase was easily deactivated. A hydrophobic treatment improved the protein-coupled content of silk cotton, viscose and PET surfaces more than threefold. Viscose prepared with the hydrophobic treatment could be reused up to 44 times and retained a static water contact angle of 131.8°. The initial rate of esterification remained high even when the amount of added water was increased to 10%. In a model application reaction of oleic acid and ethanol with 8% (v/v) added water, the acid conversion rate of post-hydrophobic treated immobilized lipase improved by at least 10% in each of five batches. These results suggest that a hydrophobic surface results in a lower amount of adsorbed water on the support membrane and provides a more suitable microenvironment for the enzymes. Nonwoven viscose could be a potential enzyme immobilization matrix for industrial processes. [Copyright &y& Elsevier]

In this work, the acetone-butanol-ethanol (ABE) fermentation was upgraded in order to improve its economy. Fed-batch fermentation was integrated with two-stage gas stripping-pervaporation unit. The permeated ABE condensate was used as substrate for oleates production. Candida sp. 99–125 cells, being rich in lipase activity, were used as full-cell catalyst. Different ABE feeding strategies in the esterification process were compared. As results, 10.1%, 68.6% and 72.5% of butyl oleate were obtained in the one-step added scenario, the stepwise-added scenario, and the simultaneous fed-batch scenario, respectively. The novel hybrid process was energy-saving, environmentally friendly and profitable, showing promise in future industrialization. [ABSTRACT FROM AUTHOR]

Finishing of silk fabric was achieved by using amino-functional polydimethylsiloxane (PDMS) and lipase from Candida sp. 99-125 was immobilized on the treated silk fabrics. Hydrophobic fabrics were obtained by dipping the native fabric in 0.125-0.25% (w/v) PDMS solution and dried at 70°C. The direct adsorption on PDMS-treated fabric was verified to be a better strategy for lipase immobilization than that by covalent binding. Compared to unfinished fabrics, the hydrolytic activity of immobilized enzyme on the finished fabric was improved by 1.6 times. Moreover, the activity of immobilized enzymes on hydrophobic fabrics was significantly improved in different concentrations of strong polar solvents such as methanol and ethanol, and in common organic solvents with different octanol-water partition coefficients (LogP). Enzymatic activity and stability in 15% water content system (added water accounted for the total reaction mixtures, v/v) showed more than 30% improvement in each batch. The amino-silicone finished fabric surface was investigated by scanning electron microscopy and X-ray photoelectron spectroscopy. The hydrophobic fabric immobilized enzyme could be recycled for more than 80 times with no significant decrease in esterification activity. PDMS-treated woven silk fabrics could be a potential support for lipase immobilization in catalytic esterification processes. [ABSTRACT FROM AUTHOR]

Highlights: [•] Lipase was absorbed on surface hydrophobic modified silk fibers. [•] Immobilized lipase and feeding methods improve synthesis of tri-TMP esters. [•] Immobilized lipas showed increase esterification activity and decrease hydrolysis activity. [•] TMP-feeding methods kept a high molar ratio of fatty acid to TMP during process. [Copyright &y& Elsevier]

Highlights: [•] A simple, efficient immobilization protocol on polyurethane foam was developed. [•] Polyethyleneimine (PEI) was used to regulate the micro-environment. [•] Immobilized lipase exhibited a long operational stability in esterification system. [Copyright &y& Elsevier]