Purification and characterisation of Saccharomyces cerevisiae external invertase isoforms

Industrial Approach to Invertase Production from Fruit Waste for Enhanced Efficiency and Conservation

This study investigates the commercial viability of repurposing fruit waste for enzyme production, specifically focusing on the invertase enzyme derived from Saccharomyces cerevisiae. By utilizing fruit pulp that incorporates mulberry, carob, Figure, and grape pulp as a nutrient source, it is observed that the culture medium containing carob pulp exhibits the highest invertase activity. Specifically, the invertase activity in this medium is approximately 2.5 times greater (12.90 U/mg protein) than that observed in the peptone medium (5.98 U/mg protein). The extract undergoes several purification steps, including ultrafiltration, ammonium sulfate precipitation, dialysis, and ion-exchange chromatography (purification ratio: 12.11 times, yield: 26.93%). The purified enzyme is immobilized using alginate beads, improving pH and thermal stability. The immobilized enzyme exhibits optimal activity between pH 3.50 and pH 7.00, thereby broadening the enzyme's high-activity pH range. The thermal stability of the immobilized invertase enzyme is significantly improved, especially at 65 °C. Activity studies in the presence of metal ions and certain chemicals have been conducted. The immobilized enzyme's activity increases by approximately 40% in the presence of Ca2+ and Mg2+, and the immobilized enzyme maintains its activity in the presence of detergents such as SDS, Tween-20, and organic solvents like ethanol and methanol. The potential for the reuse of immobilized invertase was investigated under standard assay conditions. After 20 cycles, the immobilized enzyme was found to retain 80% of its initial activity. Overall, the study establishes the commercial potential of fruit pulp, typically discarded in fruit juice production, as a valuable source for obtaining an invertase enzyme. Furthermore, this study also aims to develop a suitable purification process for invertase in the fruit juice industry. By harnessing fruit waste and implementing innovative enzyme production strategies, industries can enhance their efficiency, reduce their environmental footprint, and optimize resource utilization.

A monolithic stationary phase with dendritic nanostructures for the separation of PEGylated proteins

Separation of PEGylated protein mixtures into individual species is a challenging procedure, and many efforts have been focused on creating novel chromatographic supports for this purpose. In this study, a new monolithic stationary phase with hyperbranched nanostructures was chemically synthesized. For this, monoliths with a support matrix of poly (glycidyl methacrylate-co-ethylene dimethacrylate) and ethylenediamine chemistry were modified with third-generation dendrons with butyl-end groups. The new monolith was analyzed by infrared spectroscopy, confirming the dendron with butyl ligands and exhibited low mass transfer resistance as observed by breakthrough frontal analysis. This support was able to separate mono-PEG ribonuclease A from the PEGylation mixture, indicated by a single band (∼30 kDa) in the electrophoretic analysis. Moreover, the separation of mono-PEGylated positional isomers was probably observed, as the protein with ∼30 kDa was found in two separate peaks. Interestingly, the dendronized monolith allowed the separation of the reaction mixture into individual PEGylated species when using high ammonium sulfate concentrations (2 M). A correlation between the PEGylation degree and the strength of the hydrophobic interactions on the monolith was observed. This chromatographic approach combines the natural branched architecture of dendrons and the higher capabilities of the monoliths enhancing the hydrophobic surface area, and therefore the interaction between the PEGylated proteins and ligands. Thus, the novel support represents a novel platform for the purification of PEGylated from non-PEGylated proteins with biotechnological applications.

Biscuits Prepared with Enzymatically-Processed Soybean Meal Are Rich in Isoflavone Aglycones, Sensorially Well-Accepted and Stable during Storage for Six Months

Soybean meal (SBM) is a co-product of the soybean oil industry that is rich in bioactive compounds, such as isoflavones. We aimed to study the effects of processing SBM by fermentation (Saccharomyces cerevisiae) (FSBM) and enzymatic hydrolysis (CelluMax C, a commercial cellulase) (ESBM) on its chemical composition, with emphasis on isoflavones. Fermentation increased protein content by 9%, ash content by 7%, dietary fiber by 11% and minerals by up to 38%, except for iron, which decreased by 26%. Fermentation completely removed oligosaccharides from SBM, while enzymatic processing decreased oligosaccharides by 45% in SBM. Both processes converted glycosylated isoflavones into the corresponding aglycones, the content of which increased by up to 7.7-fold. Biscuits containing SBM, FSBM and ESBM could be labeled as dietary sources of dietary fibers, potassium, phosphorous, calcium and zinc, as well as high in proteins, copper, iron, manganese and magnesium. While FSBM biscuits had lower sensory scores compared to SBM biscuits, ESBM biscuits had equivalent scores. During storage for 180 days at room temperature, the isoflavone profile of all biscuits remained stable. Moreover, storage did not impair microbiological and sensory qualities of any biscuits. Altogether, ESBM biscuits show great marketing potential.

The Influence of Yarrowia lipolytica Glycosylation on the Biochemical Properties and Oligomerization of Heterologous Invertase

Invertases are important enzymes used in the food industry. Despite many studies on the invertase-encoding SUC2 gene expression in the industrial yeast Yarrowia lipolytica, no biochemical characteristics of this enzyme expressed as heterologous protein have been provided. Here, two isoforms of extracellular invertase produced by Y. lipolytica were detected using ion-exchange chromatography. Specific activities of 226.45 and 432.66 U/mg for the first and second isoform, respectively, were determined. Basic characteristics of this enzyme were similar to the one isolated from Saccharomyces cerevisiae (optimum pH and temperature, metal ions inhibition, substrate specificity and fructooligosaccharides (FOS) biosynthesis). The apparent differences were higher KM for sucrose (67 mM) and lower molecular mass (66 kDa) resulting from lower N-glycosylation level (9.1% of mass). The N-glycan structures determined by MALDI-TOF and HPLC represented high mannose structures, though with much shorter chains than hypermannosylated glycans from S. cerevisiae. Furthermore, galactose was detected as the modifying sugar in the glycan structures of invertase expressed in Y. lipolytica. N-glycans did not affect invertase activity but were important for its oligomerization. The expressed enzyme aggregated into dimers, tetramers, hexamers, and octamers, as well as structures of higher molecular mass, which might be decamers, which have not been described so far in the literature.

Invertase adsorption with polymers functionalized by aspartic acid

Today, the separation and purification processes are highly preferred over the affinity interactions in the scientific world. Among the materials used for this purpose, magnetic particles and cryogels are very popular. Both polymeric structures have their advantages and disadvantages. In this study, poly(2-Hydroxyethyl methacrylate-N-methacryloyl-L-aspartic acid), poly(HEMA-MAsp), magnetic microparticles, and cryogels were synthesized, and adsorption performances of both polymeric structures were investigated by using invertase from aqueous systems. Invertase (β-fructofuranoside fructohydrolase, EC 3.2.1.26) is a commercially important enzyme used in the food industry to obtain the product called invert sugar, which consists of a mixture of equivalent amounts of glucose and fructose. Therefore, it was preferred as a model enzyme in adsorption studies of polymeric structures. According to the results, 104.1 mg g−1 and 135.5 mg g−1 of adsorption capacity values were obtained for cryogel and magnetic microparticle forms, respectively. Increasing temperature slightly reduced the adsorption capacity of both polymeric structures. In the adsorption/desorption cycle studies performed five times with poly(HEMA-MAsp) polymers, both forms were found to have high reusable properties. It was determined that the activity of invertase immobilized on polymeric structures was preserved at a rate of 83.6% for the particle form and 89.2% for the cryogel form.

Highly reusable invertase biocatalyst: Biological fibrils functionalized by photocrosslinking

Here we report a novel strategy for the immobilization of invertase using amyloid-like fibrils as a support. Optimal conditions to get Tyr-Tyr covalent binding between invertase and the support were determined using a photocrosslinking approach. The biological fibrils with invertase activity turn into microstructured catalysts according to electron microscopy outcomes. Thermal and storage stability as well as optimal pH and temperature of the enzyme were conserved. Moreover, the immobilized enzyme recovered by low g-force centrifugation retained 83% of its initial enzymatic activity after 15 reuse cycles. Considering that enzyme cost is the most significant part of the overall fee of enzymatic biomass conversion, the highly efficient recovery/reuse strategy described herein becomes relevant. Besides, it can also be applied to the immobilization of other enzymes for industrial biocatalysis.

Increased yield of enzymatic synthesis by chromatographic selection of different N-glycoforms of yeast invertase

Invertases are glycosidases applied for synthesis of alkyl glycosides that are important and effective surfactants. Stability of invertases in the environment with increased content of organic solvent is crucial for increase of productivity of glycosidases. Their stability is significantly influenced by N-glycosylation. However, yeast N-glycosylation pathways may synthesize plethora of N-glycan structures. A total natural crude mixture of invertase glycoforms (EINV) extracted from Saccharomyces cerevisiae was subfractionated by anion-exchange chromatography on industrial monolithic supports to obtain different glycoforms (EINV1-EINV3). Separated glycoforms exhibited different stabilities in water-alcohol solutions that are in direct correlation with the amount of phosphate bound to N-glycans. Observed differences in stability of different invertase glycoforms were used to improve productivity of methyl β-d-fructofuranoside (MF) synthesis. The efficiency and yield of MF synthesis were improved more than 50% when the most stabile glycoform bearing the lowest amount of phosphorylated N-glycans is selected and utilized. These data underline the importance of analysis of glycan structures attached to glycoproteins, demonstrate different impact of N-glycans on the surface charge and enzyme stability in regard to particular reaction environment, and provide a platform for improvement of yield of industrial enzymatic synthesis by chromatographic selection of glycoforms on monolithic supports.

Comparative evaluation of extracellular β-d-fructofuranosidase in submerged and solid-state fermentation produced by newly identified Bacillus subtilis strain

AIMS

To screen and identify a potential extracellular β-d-fructofuranosidase or invertase-producing bacterium from soil, and comparatively evaluate the enzyme biosynthesis under submerged and solid-state fermentation (SSF).

METHODS AND RESULTS

Extracellular invertase-producing bacteria were screened from soil. Identification of the potent bacterium was performed based on microscopic examinations and 16S rDNA molecular sequencing. Bacillus subtilis LYN12 invertase secretion was surplus with wheat bran humidified with molasses medium (70%), with elevated activity at 48 h and 37°C under SSF, whereas under submerged conditions, increased activity was observed at 24 h and 45°C in the molasses medium. The study revealed a simple fermentative medium for elevated production of extracellular invertase from a fast growing Bacillus strain.

CONCLUSIONS

Bacterial invertases are scarce and limited reports are available. By far, this is the first report on the comparative analysis of optimization of extracellular invertase synthesis from B. subtilis strain by submerged and SSF. The use of agricultural residues increased yields resulting in the development of a cost-effective and stable approach.

SIGNIFICANCE AND IMPACT OF THE STUDY

Bacillus subtilis LYN12 invertase possesses excellent fermenting capability to utilize agro-industrial residues under submerged and solid-state conditions. This could be a beneficial candidate in food and beverage processing industries.

Purification and biochemical characterization of an extracellular β-d-fructofuranosidase from Aspergillus sp

This study focused on the purification and characterization of an extracellular β-d-fructofuranosidase or invertase from Aspergillus sojae JU12. The protein was purified by size exclusion chromatography with 5.41 fold and 10.87% recovery. The apparent molecular mass of the enzyme was estimated to be ~ 35 kDa using SDS-PAGE and confirmed by deconvoluted mass spectrometry. The fungal β-d-fructofuranosidase was suggested to be a monomer by native PAGE and zymography, and was found to be a glycoprotein possessing 68.92% carbohydrate content. The products of enzyme hydrolysis were detected by thin layer chromatography and revealed the monosaccharide units, d-glucose and d-fructose. β-d-fructofuranosidase showed enhanced activity at broad pH 4.0-9.0 and activity at a temperature range from 30 to 70 °C, while the enzyme was stable at pH 8.0 and 40 °C, respectively. The β-d-fructofuranosidase activity was lowered by metal ion inhibitors Ag2+ and Hg2+ whereas elevated by SDS and β-ME. The fungal β-d-fructofuranosidase was capable of hydrolyzing d-sucrose and the kinetics were determined by Lineweaver-Burk plot with Km of 10.17 mM and Vmax of 0.7801 µmol min-1. Additionally, the extracellular β-d-fructofuranosidase demonstrated tolerance to high ethanol concentrations indicating its applicability in the production of alcoholic fermentation processes.

Utilization of chitosan as an antimicrobial agent for pasteurized palm sap (Borassus flabellifer Linn.) during storage

The objective of this research was to assess the potential of chitosan for improvement the quality of pasteurized palm sap during storage. First, the effect of chitosan content on sensory attributes was investigated to select suitable concentration of chitosan for further study. Fresh palm sap was enriched with chitosan at various concentrations (0-2 g/L) and pasteurized at 80 °C for 10 min, consequently evaluated by consumers. It was found that samples added chitosan in the range of 0-1.00 g/L were considered acceptable. Thus, the addition chitosan in the concentration of 0-1.00 g/L was chosen for further study. The sample without chitosan addition was used as a control sample. Each selected sample was determined for their qualities during storage at 1 week interval. It was found that lightness and transmittance values of all samples tended to increase during storage. Lower PPO and invertase activity were observed in all chitosan-treated samples compared to control sample. Chitosan could minimize the loss of sucrose and the increase in glucose and fructose content during storage. In addition, an increase in chitosan concentration resulted in the increase in DPPH radical scavenging activity. Furthermore, the addition of chitosan could retard the development of microorganism during storage as demonstrated by lower microbial loads compared to control sample. It can be concluded that a combination of pasteurization with chitosan addition (0.50 g/L) and low temperature storage could preserve palm sap for approximately 6 weeks. Thus, the incorporation of chitosan in palm sap could be used as an alternative way to extend shelf life of pasteurized palm sap.

Complete sucrose hydrolysis by heat-killed recombinant Pichia pastoris cells entrapped in calcium alginate

Background

An ideal immobilized biocatalyst for the industrial-scale production of invert sugar should stably operate at elevated temperatures (60-70°C) and high sucrose concentrations (above 60%, w/v). Commercial invertase from the yeast Saccharomyces cerevisiae is thermolabile and suffers from substrate inhibition. Thermotoga maritima β-fructosidase (BfrA) is the most thermoactive and thermostable sucrose-hydrolysing enzyme so far identified and allows complete inversion of the substrate in highly concentrated solutions.

Results

In this study, heat-killed Pichia pastoris cells bearing N-glycosylated BfrA in the periplasmic space were entrapped in calcium alginate beads. The immobilized recombinant yeast showed maximal sucrose hydrolysis at pH 5–7 and 90°C. BfrA was 65% active at 60°C and had no activity loss after incubation without the substrate at this temperature for 15 h. Complete inversion of cane sugar (2.04 M) at 60°C was achieved in batchwise and continuous operation with respective productivities of 4.37 and 0.88 gram of substrate hydrolysed per gram of dry beads per hour. The half-life values of the biocatalyst were 14 and 20 days when operated at 60°C in the stirred tank and the fixed-bed column, respectively. The reaction with non-viable cells prevented the occurrence of sucrose fermentation and the formation of by-products. Six-month storage of the biocatalyst in 1.46 M sucrose (pH 5.5) at 4°C caused no reduction of the invertase activity.

Conclusions

The features of the novel thermostable biocatalyst developed in this study are more attractive than those of immobilized S. cerevisiae cells for application in the enzymatic manufacture of inverted sugar syrup in batch and fixed-bed reactors.

Stimulation of extracellular invertase production from spent yeast when sugarcane pressmud used as substrate through solid state fermentation

Efforts were made to utilize the waste/by-product of two agro-process industries namely pressmud from sugar processing industries and spent yeast from distilleries manufacturing ethanol from cane molasses, for the production of microbial invertase. Our experimentation indicated that these two sources could be ideally utilized for the production of invertase through solid substrate fermentation (SSF). SSF with spent yeast had given highest specific activity of 430 U/mg in 72 h of fermentation. Inoculum percentage of yeast cells on pressmud was optimized as 50% (w/w) with a combination inoculum of spent yeast and fresh cultured yeast at a ratio of 7:3. Crude enzyme was characterized for optimum pH and temperature and maximum activity was recorded at pH 5.0 and at a temperature of 40°C. Impacts of metal ions and detergents on invertase action were studied in which Mn²⁺, Fe³⁺, Al³⁺ and detergents had enhanced the activity of the enzyme whereas Cu²⁺ and Zn²⁺ inhibited the enzyme activity. Purification of 9.8 folds was obtained by using three phase partition method.

Thermodynamics and structural features of the yeast Saccharomyces cerevisiae external invertase isoforms in guanidinium-chloride solutions

Recently, four external invertase isoforms (EINV1, EINV2, EINV3, and EINV4) have been isolated from S. cerevisiae. However, there is nothing known about their structural features and thermodynamics of unfolding. Since this information is essential for understanding their functioning at the molecular level as well as applicable in the food industry, we investigated guanidinium-chloride induced structural changes of the isoforms by CD and fluorescence spectroscopy. The resulting unfolding curves measured for each isoform at different temperatures were described simultaneously by a reversible two-state model to obtain the corresponding thermodynamic parameters. Here, we show that they are different for different isoforms and demonstrate that they correlate with the surface charge density of the native isoforms which follows the order EINV1 < EINV2 < EINV3 < EINV4. It appears that at physiological temperatures the thermodynamic stability of the isoforms follows the same order, while above 55 °C, the order is the opposite EINV1 > EINV2 > EINV3 ≈ EINV4. This suggests that increasing the efficiency of the food industry processes involving invertase would require the application of EINV3 and/or EINV4 at physiological temperatures and EINV1 at elevated temperatures.

Immobilization of cell wall invertase modified with glutaraldehyde for continuous production of invert sugar

Yeast cell wall invertase (CWI) was modified with dimethyl suberimidate, glutaraldehyde, formaldehyde, and sodium periodate. Retained activity after modification was 45% for CWI modified with formaldehyde, 77% for CWI modified with sodium periodate, 80% for CWI modified with glutaraldehyde, and 115% for CWI modified with dimethyl suberimidate. Chemically modified and native CWIs showed significantly broad pH stability (pH 3-11), whereas after incubations at 50, 60, and 70 °C, CWI modified with glutaraldehyde showed the highest thermostability. Optimum pH for CWI modified with glutaraldehyde was between 4 and 5, whereas optimum temperature was at 60 °C. Comparison to CWI modified with glutaraldehyde after immobilization within alginate beads showed broader pH optimum (4.0-5.5) as well as broader temperature optimum (55-70 °C). Column bed reactor packed with the immobilized CWI modified with glutaraldehyde was successfully used for the 95% inversion of 60% (w/w) sucrose at the flow rate of 3 bed volumes per hour, pH 4.9, and 45 °C. A 1 month productivity of 3844 kg of inverted sugar/kg of the immobilisate was obtained.