Immobilization of Candida antarctica lipase B onto Purolite® MN102 and its application in solvent-free and organic media esterification.

The aim of this study was to develop simple and efficient method for immobilization of Candida antarctica lipase B onto hydrophobic anion exchange resin Purolite® MN102 and to apply immobilized catalyst for the enzymatic synthesis of two valuable esters-isoamyl acetate and L-ascorbyl oleate. At optimized conditions (1 M phosphate buffer pH = 7, 7 h at 25 °C, and 18.75 mg of offered proteins g-1 of support), immobilized lipase with hydrolytic activity of 888.4 p-nitrophenyl butyrate units g-1 was obtained. Afterwards, preparation was applied for the solvent-free synthesis of isoamyl acetate from triacetin and isoamyl alcohol. At 75 °C, 1 M of isoamyl alcohol, and 6 mg ml-1 of enzyme 100 % yield was achieved in 6 h, while at prolonged reaction times, complete conversion was enabled even at lower temperatures, lower lipase loadings, and higher substrate concentrations. After 15 consecutive reuses (60 h), activity of catalyst dropped to 50 % of its initial value and total amount of 1.31 mol (170.55 g) of ester with 1 g of biocatalyst was produced. Even higher operational stability of lipase (25 % loss of activity in 200 h) was observed in the synthesis of L-ascorbyl oleate performed in organic solvent (t-butanol). Multiple use of one batch of immobilized biocatalyst in both cases led to a significant process cost reduction and substantial increment of corresponding productivities.

Influence of fatty acid on lipase-catalyzed synthesis of ascorbyl esters and their free radical scavenging capacity.

Fatty acid (FA) ascorbyl esters are recently emerging food, cosmetic, and pharmaceutical additives, which can be prepared in an eco-friendly way by using lipases as catalysts. Because they are amphiphilic molecules, which possess high free radical scavenging capacity, they can be applied as liposoluble antioxidants as well as emulsifiers and biosurfactants. In this study, the influence of a wide range of acyl donors on ester yield in lipase-catalyzed synthesis and ester antioxidant activity was examined. Among saturated acyl donors, higher yields and antioxidant activities of esters were achieved when short-chain FAs were used. Oleic acid gave the highest yield overall and its ester exhibited a high antioxidant activity. Optimization of experimental factors showed that the highest conversion (60.5%) in acetone was achieved with 5 g L(-1) of lipase, 50 mM of vitamin C, 10-fold molar excess of oleic acid, and 0.7 mL L(-1) of initial water. Obtained results showed that even short- and medium-chain ascorbyl esters could be synthesized with high yields and retained (or even exceeded) free radical scavenging capacity of l-ascorbic acid, indicating prospects of broadening their application in emulsions and liposomes.

Postindustrial Jute Waste as a Support for Nano-Carbon Nitride Photocatalyst: Influence of Chemical Pretreatment.

Non-woven jute (NWJ) produced from carpet industry waste was oxidized by H2O2 or alkali-treated by NaOH and compared with water-washed samples. Changes in the structure of the NWJ, tracked by X-ray diffraction (XRD), showed that both chemical treatments disrupt hydrogen bond networks between cellulose Iß chains of the NWJ fibers. Thereafter, nano-carbon nitride (nCN) was impregnated, using a layer-by-layer technique, onto water-washed jute samples (nCN-Jw), NaOH-treated samples (nCN-Ja) and-H2O2 treated samples (nCN-Jo). Analysis of the Fourier transform infrared spectroscopy (FTIR) spectra of the impregnated samples revealed that nCN anchors to the water-washed NWJ surface through hemicellulose and secondary hydroxyl groups of the cellulose. In the case of chemically treated samples, nCN is preferentially bonded to the hydroxymethyl groups of cellulose. The stability and reusability of prepared nCN-jute (nCN-J) samples were assessed by tracking the photocatalytic degradation of Acid Orange 7 (AO7) dye under simulated solar light irradiation. Results from up to ten consecutive photocatalytic cycles demonstrated varying degrees of effectiveness across different samples. nCN-Jo and nCN-Ja samples exhibited declining effectiveness over cycles, attributed to bond instability between nCN and jute. In contrast, the nCN-Jw sample consistently maintained high degradation rates over ten cycles, with a dye removal percentage constantly above 90%.

Evaluation of ß-galactosidase from Lactobacillus acidophilus as biocatalyst for galacto-oligosaccharides synthesis: Product structural characterization and enzyme immobilization.

ß-Galactosidase is an important industrial enzyme that catalyzes reaction of lactose hydrolysis and recently more interesting reaction of transgalactosylation, yielding a highly valuable group of prebiotic compounds named galacto-oligosaccharides (GOS). In this paper, parameters for achieving high yields of tailor-made GOS using crude ß-galactosidase obtained from Lactobacillus acidophilus ATCC 4356, probiotic bacteria regarded as safe for human consumption, were optimized. At the same time, detailed structural elucidation of obtained GOS was conducted, and it was concluded that ß-galactosidase from L. acidophilus shows a particular specificity towards the formation of ß-(1→6) glycosidic bonds. In order to develop more stable and economically cost-effective preparation, crude enzyme was successfully immobilized on a methacrylic polymer carrier Lifetech ECR8409, leading to its simultaneous 2-fold purification. This immobilized preparation showed unchanged specificity towards the transgalactosylation reaction, thus yielding 86 g/l GOS under the previously optimized conditions (lactose concentration 400 g/l in 0.1 M sodium phosphate buffer, pH 6.8 and temperature 50°C).

Structural Elucidation of Enzymatically Synthesized Galacto-oligosaccharides Using Ion-Mobility Spectrometry-Tandem Mass Spectrometry.

Galacto-oligosaccharides (GOS) represent a diverse group of well-characterized prebiotic ingredients derived from lactose in a reaction catalyzed with ß-galactosidases. Enzymatic transgalactosylation results in a mixture of compounds of various degrees of polymerization and types of linkages. Because structure plays an important role in terms of prebiotic activity, it is of crucial importance to provide an insight into the mechanism of transgalactosylation reaction and occurrence of different types of ß-linkages during GOS synthesis. Our study proved that a novel one-step method, based on ion-mobility spectrometry-tandem mass spectrometry (IMS-MS/MS), enables complete elucidation of GOS structure. It has been shown that ß-galactosidase from Aspergillus oryzae has the highest affinity toward formation of ß-(1→3) or ß-(1→6) linkages. Additionally, it was observed that the occurrence of different linkages varies during the reaction course, indicating that tailoring favorable GOS structures with improved prebiotic activity can be achieved by adequate control of enzymatic synthesis.

Sugar Beet Pulp as Leuconostoc mesenteroides T3 Support for Enhanced Dextransucrase Production on Molasses.

Sugar beet pulp (SBP) and molasses, as an agro industrial waste material, are produced in large amounts annually. Thus, a major challenge nowadays is to develop procedures that could increase the value of the generated waste. In this study, SBP as a support for cell immobilization and molasses as a source of nutrients were used for a dextransucrase (DS) production by Leuconostoc mesenteroides T3. The influence of SBP in native form (SBP-N) and after treatment with NaOH (SBP-NaOH) on DS production was investigated. The optimal medium composition for the maximum DS production was determined by varying the concentration of molasses, SBP, and sucrose. The maximum DS yield of 2.02 U/ml was obtained in the medium with 2.5 % of molasses, 2.5 % SBP-NaOH, and 4 % of sucrose concentration. Scanning electron microscopy (SEM) showed immobilization of Lc. mesenteroides T3 cells onto SBP-NaOH. According to the obtained results, the production of DS on molasses could be improved by using NaOH-treated SBP as a carrier for whole-cell immobilization. Our study reveals the basis for the development of process for DS production with additional reduction of expenses by using waste materials for obtaining the valuable biotechnological product.