β-Galactosidase from Kluyveromyces lactis cell disruption and enzyme immobilization using a cellulose–gelatin carrier system

Magnetic core-shell cellulose system for the oriented immobilization of a recombinant β-galactosidase with a protein tag

The objective of this study was to immobilize a recombinant β-galactosidase (Gal) tagged with a cellulose-binding domain (CBD) onto a magnetic core-shell (CS) cellulose system. After 30 min of reaction, 4 U/capsule were immobilized (CS@Gal), resulting in levels of yield and efficiency exceeding 80 %. The optimal temperature for β-galactosidase-CBD activity increased from 40 to 50 °C following oriented immobilization. The inhibitory effect of galactose decreased in the enzyme reactions catalyzed by CS@Gal, and Mg2+ increased the immobilized enzyme activity by 40 % in the magnetic CS cellulose system. The relative enzyme activity of the CS@Gal was 20 % higher than that of the soluble enzyme activity after 20 min at 50 °C. The CS support and CS@Gal capsules exhibited an average size of 8 ± 1 mm, with the structure of the shell (alginate-pectin-cellulose) enveloping and isolating the magnetic core. The immobilized β-galactosidase-CBD within the magnetic CS cellulose system retained ∼80 % of its capacity to hydrolyze lactose from skim milk after 10 reuse cycles. This study unveils a novel and promising support for the oriented immobilization of recombinant β-galactosidase using a magnetic CS system and a CBD tag. This support facilitates β-galactosidase reuse and efficient separation, consequently enhancing the catalytic properties of the enzyme.

Porungo cheese whey: a new substrate to produce β-galactosidase

The bioconversion of porungo cheese whey to produce β-galactosidase in batch system was studied. The whey released after curd cutting and precipitation during porungo cheese production was collected in borosilicate flasks. Two strains of Kluyveromyces marxianus, CCT 4086 and CBS 6556, and whey supplementation with different nitrogen sources were evaluated. Different temperatures (30 °C and 37 °C) and pH values (5.0 to 7.0) were investigated to establish the best conditions for enzyme production. The highest enzymatic activity was obtained by K. marxianus CCT 4086 in porungo cheese whey supplemented with yeast extract (16.73 U mL-1). K. marxianus CCT 4086 produced superior β-galactosidase activity when compared to CBS 6556 for all media tested (ranging from 11.69 to 14.40 U mL-1). Highest β-galactosidase activity was reached under conditions of pH 7.0 and 30 °C using K. marxianus CCT 4086 in the better media composition. The lowest enzymatic activity was observed at 37 °C for all pH values tested (10.69 U mL-1 to 13.94 U mL-1) and a highest β-galactosidase activity was reached in pH 7.0 for both two temperatures (11.42 to 15.93 U mL-1). Porungo cheese whey shows potential for industrial β-galactosidase production by microbial fermentation.

β-Galactosidase from Kluyveromyces lactis: Characterization, production, immobilization and applications - A review

A review on the enzyme β-galactosidase from Kluyveromyces lactis is presented, from the perspective of its structure and mechanisms of action, the main catalyzed reactions, the key factors influencing its activity, and selectivity, as well as the main techniques used for improving the biocatalyst functionality. Particular attention was given to the discussion of hydrolysis, transglycosylation, and galactosylation reactions, which are commonly mediated by this enzyme. In addition, the products generated from these processes were highlighted. Finally, biocatalyst improvement techniques are also discussed, such as enzyme immobilization and protein engineering. On these topics, the most recent immobilization strategies are presented, emphasizing processes that not only allow the recovery of the biocatalyst but also deliver enzymes that show better resistance to high temperatures, chemicals, and inhibitors. In addition, genetic engineering techniques to improve the catalytic properties of the β-galactosidases were reported. This review gathers information to allow the development of biocatalysts based on the β-galactosidase enzyme from K. lactis, aiming to improve existing bioprocesses or develop new ones.

Porungo cheese whey: β-galactosidase production, characterization and lactose hydrolysis

Abstract This study evaluated the lactose hydrolysis by immobilized β-galactosidase, which was produced by Kluyveromyces marxianus using porungo cheese whey as substrate. Initially, the yeast was cultivated in porungo cheese medium at 30 °C and 200 rpm, showing a maximal β-galactosidase production of 14.19 U mL-1. The crude extract obtained was used to evaluate the enzymatic hydrolysis in lactose solution. The optimal pH and temperature of the free and immobilized enzyme was investigated, whereas the lactose hydrolysis was carried out using two enzyme solutions (total activities of 2 U and 6 U) for both forms of the biocatalyst. Ca-alginate immobilization of β-galactosidase increased optimal temperature range to 40 °C, compared to the value for the free enzyme, which was 37 °C. The optimal pH was also increased by immobilization to 7.0, from pH 6.5 observed for the free enzyme. The highest lactose hydrolysis conversion was 15.82% using 6 U of free enzyme and 13.77% for 2 U of immobilized enzyme. Although, free enzyme showed higher conversion rates in the initial reaction time, the immobilized enzyme kept operational stability throughout reaction time, suggesting the advantage of using this technology. The use of porungo cheese whey allowed to aggregate value to this agro-industrial by-product, with the concomitant production of β-galactosidase to be used in the food industry chain itself.

Improving the catalytic performance of Pichia pastoris whole-cell biocatalysts by fermentation process

Whole-cell biocatalysts have a wide range of applications in many fields. However, the transport of substrates is tricky when applying whole-cell biocatalysts for industrial production. In this research, P. pastoris whole-cell biocatalysts were constructed for rebaudioside A synthesis. Sucrose synthase was expressed intracellularly while UDP-glycosyltransferase was displayed on the cell wall surface simultaneously. As an alternative method, a fermentation process is applied to relieve the substrate transport-limitation of P. pastoris whole-cell biocatalysts. This fermentation process was much simpler, more energy-saving, and greener than additional operating after collecting cells to improve the catalytic ability of whole-cell biocatalysts. Compared with the general fermentation process, the protein production capacity of cells did not decrease. Meanwhile, the activity of whole-cell biocatalysts was increased to 262%, which indicates that the permeability and space resistance were improved to relieve the transport-limitations. Furthermore, the induction time was reduced from 60 h to 36 h. The fermentation process offered significant advantages over traditional permeabilizing reagent treatment and ultrasonication treatment based on the high efficiency and simplicity.

Fermentation process was applied to relieve the substrate transport-limitation of P. pastoris whole-cell biocatalysts, which was much simpler, more energy-saving and greener than c traditional permeabilizing reagent and ultrasonication treatment.

Enzyme Immobilization on Nanomaterials for Biosensor and Biocatalyst in Food and Biomedical Industry

Enzymes exhibit a great catalytic activity for several physiological processes. Utilization of immobilized enzymes has a great potential in several food industries due to their excellent functional properties, simple processing and cost effectiveness during the past decades. Though they have several applications, they still exhibit some challenges. To overcome the challenges, nanoparticles with their unique physicochemical properties act as very attractive carriers for enzyme immobilization. The enzyme immobilization method is not only widely used in the food industry but is also a component methodology in the pharmaceutical industry. Compared to the free enzymes, immobilized forms are more robust and resistant to environmental changes. In this method, the mobility of enzymes is artificially restricted to changing their structure and properties. Due to their sensitive nature, the classical immobilization methods are still limited as a result of the reduction of enzyme activity. In order to improve the enzyme activity and their properties, nanomaterials are used as a carrier for enzyme immobilization. Recently, much attention has been directed towards the research on the potentiality of the immobilized enzymes in the food industry. Hence, the present review emphasizes the different types of immobilization methods that is presently used in the food industry and other applications. Various types of nanomaterials such as nanofibers, nanoflowers and magnetic nanoparticles are significantly used as a support material in the immobilization methods. However, several numbers of immobilized enzymes are used in the food industries to improve the processing methods which not only reduce the production cost but also the effluents from the industry.

A novel autolysis system controlled by magnesium and its application to poly (3-hydroxypropionate) production in engineered Escherichia coli

The release of intracellular products, especially polyhydroxyalkanoates, is still a great challenge in industry. To solve this bottleneck, a novel autolysis system strictly controlled with magnesium was constructed and applied to poly(3-hydroxypropionate) production in engineered Escherichia coli. The autolysis system was constructed by inserting the 5'untranslated region (5'UTR) behind promoter PmgtA with lysis genes (S, R, and Rz, from E. coli) overexpressed. The autolysis system functioned well (lysis efficiency of more than 90%) in the P3HP producer with double plasmids containing lysis genes and P3HP biosynthesis genes, whereas the P3HP production was reduced due to plasmid losses. After the autolysis genes and P3HP biosynthesis genes were integrated into one plasmid, the P3HP content of 72.7% (2.4 times of the control) and the plasmid stability of 79.8 ± 3.1% were achieved in strain Q2646 with promoter PmgtA-UTR. However, the strain Q2647 with promoter PmgtA could not accumulate P3HP because of rapid cell lysis. The novel autolysis system activated in Mg²⁺-depleted conditions proves to be feasible for polyhydroxyalkanoates production, which may have great application potential for other intracellular products.

Anti-degradation gelatin films crosslinked by active ester based on cellulose

An anti-degradation gelatin film crosslinked by an active ester based on MCC was prepared for applications in the food industry, medical engineering, agriculture, etc.

Chitosanase Immobilization Using Composite Carrier of Sodium Alginate/Cellulose

Sodium alginate and cellulose were combined to use as a composite carrier forPseudomonassp. CUY8 chitosanase immobilization. For free enzyme, immobilized chitosanase within different carriers of sodium alginate and composite carrier, Km values were 1.919, 9.27, and 5.91µM, respectively. The increase of Km value of immobilized chitosanase with composite carrier was lower than that of single carrier. This indicates that the composite carrier of sodium alginate/ cellulose improves the affinity of chitosanase to the substrate. Furthermore, chitosanase immobilization using composite carrier shows improved thermal stability ranging from 65 to 80°C, and enzyme residual activities were more than 75%. The effects of ratio of enzyme to substrate on chitooligosaccharides (COS) production were determined, and COS yields with composite carrier was 68% at optimum ratio of 1:1. Since the immobilization process using composite carrier is simple and effective, this method could be used for the industrial production of COS.

Silica-carrageenan hybrids used for cell immobilization realizing high-temperature degradation of nitrile substrates

In this work the application of hybrid materials, containing TEOS as source of SiO2 and k-carrageenan in different percentage, synthesized by the sol-gel method at room temperature was studied. They were used as matrices for entrapment of whole Bacillus sp. UG-5B cells, producers of thermostable nitrilase. The effect of the surface area and size and quantity of pores in the synthesized materials on the enzyme activity was evaluated. The process of biodegradation of different concentrations of toxic, potentially carcinogenic and mutagenic substrates by the obtained biocatalysts was investigated. The enzyme reaction takes place by the nitrilase pathway, catalysing nitrile hydrolysis directly to the corresponding carboxylic acid, forming ammonia. At batch experiments the influence of the substrate concentration of different nitriles was tested and 20 mM concentration was found most suitable. A two-step biodegradation process in a laboratory-scale column bioreactor of o-, m- and p-tolunitrile as a mixture was followed. After operation of the system for nine hours for the mixture of substrates at a flow rate of 45 mL h−1 and at 60°C, the overall conversion realized was above 90%, showing a good efficiency of the investigated process.

Beta-D-galactosidase from Enterobacter cloacae: production and some physicochemical properties

A bacterial strain isolated from soil and identified as Enterobacter cloacae had been found to be capable of producing both intra and extracellular beta-D: -galactosidase.The intracellular enzyme was thermostable and its optimum temperature, pH and time for enzyme-substrate reaction were found to be 50 degrees C, 9.0 and 5 min respectively, using ONPG as substrate. The maximum beta-galactosidase production in shake flask was achieved at 30 degrees C, pH 7.0, incubation time 72 h using 50 ml medium in 250 ml Erlenmeyer flask. Only Mg(2+) stimulated the activity of enzyme. Cetyl trimethyl ammonium bromide showed stimulatory effect on catalytic activity of the enzyme whereas EDTA inhibited enzyme activity. The enzyme retained its activity upto 55 degrees C after incubating at that temperature for 1 h.The maximum activity of crude intracellular enzyme was 14.35 IU/mg of protein. The K (m) and V (max) values of beta-galactosidase using ONPG as substrate at 50 degrees C were 2.805 mM and 37.45 x 10(-3) mM/min/mg, respectively.

Development of Glucose Biosensor by Using Gelatin and Gelatin-Polyacrylamide Supporting Systems

In this work an amperometric glucose biosensor based on surface immobilization method was developed. Glutaraldehyde was used as cross-linker to establish the immobilization of glucose oxidase onto gelatin (carrier/coating reagent). In order to increase the porosity of coating material, immobilization media was further treated by polyacrylamide. Although this treatment increased the performance of biosensor to a large extent with respect to current densities obtained, it negatively affected the long-term stability. Our biosensor showed linear response in the physiological range of blood glucose (0.05 to 6 mM), had an acceptable response time (60 seconds) and was stable for 17 repeated usages in 51 days. We obtained best results with pH values very close to physiological pH and our biosensor could work efficiently in the tested temperature range 15 to 65 degrees C.