A novel reverse micellar purification strategy for histidine tagged human interferon gamma (hIFN-γ) protein from Pichia pastoris

Mixed food waste valorization using a thermostable glucoamylase enzyme produced by a newly isolated filamentous fungus: A sustainable biorefinery approach

Food waste is a lucrative source of complex nutrients, which can be transformed into a multitude of bioproducts by the aid of microbial cell factories. The current study emphasizes isolating Glucoamylase enzyme (GA) producing strains that can effectively break down mixed food waste (MW), which serves as a substrate for biomanufacturing. The screening procedure relied heavily on the growth of isolated fungi on starch agar media, to specifically identify the microbes with the highest starch hydrolysis potential. A strain displayed the highest GA activity of 2.9 ± 0.14 U/ml which was selected and identified as Aspergillus fumigatus via molecular methods of identification. Exposure of the A. fumigatus with 200 mM Ethyl methanesulphonate (EMS) led to a 23.79% increase compared to the wild-type GA. The growth conditions like cultivation temperature or the number of spores in the inoculum were investigated. Further, maximum GA activity was exhibited at pH 5, 55 °C, and at 5 mM Ca2+ concentration. The GA showed thermostability, retaining activity even after long periods of exposure to temperatures as high as 95 °C. The improvement of hydrolysis of MW was achieved by Taguchi design where a maximum yield of 0.57 g g-1 glucose was obtained in the hydrolysate. This study puts forth the possibility that mixed food waste, despite containing spices and other microbial growth-inhibitory substances, can be efficiently hydrolyzed to release glucose units, by robust fungal cell factories. The glucose released can then be utilized as a carbon source for the production of value-added products.

Advanced Insights into Walnut Protein: Structure, Physiochemical Properties and Applications

Facing extreme pressure from an increasing population and climate degeneration, it is important to explore a green, safe and environmentally sustainable food source, especially for protein-enriched diets. Plant proteins have gained much attention in recent years, ascribing to their high nutritional value and environmental friendliness. In this review, we summarized recent advances in walnut protein with respect to its geographical distribution, structural and physiochemical properties and functional attributes. As a worldwide cultivated and largely consumptive crop, allergies and some physicochemical limitations have also led to a few concerns about walnut protein. Through comprehensive analysis and discussion, some strategies may be useful for future research, extraction and processing of walnut protein.

Walnut Protein: A Rising Source of High-Quality Protein and Its Updated Comprehensive Review

Recently, plant protein as a necessary nutrient source for human beings, a common ingredient of traditional processed food, and an important element of new functional food has gained prominence due to the increasing demand for healthy food. Walnut protein (WP) is obtained from walnut kernels and walnut oil-pressing waste and has better nutritional, functional, and essential amino acids in comparison with other vegetable and grain proteins. WP can be conveniently obtained by various extraction techniques, including alkali-soluble acid precipitation, salting-out, and ultrasonic-assisted extraction, among others. The functional properties of WP can be modified for desired purposes by using some novel methods, including free radical oxidation, enzymatic modification, high hydrostatic pressure, etc. Moreover, walnut peptides play an important biological role both in vitro and in vivo. The main activities of the walnut peptides are antihypertensive, antioxidant, learning improvement, and anticancer, among others. Furthermore, WP could be applied in the development of functional foods or dietary supplements, such as delivery systems and food additives, among others. This review summarizes recent knowledge on the nutritional, functional, and bioactive peptide aspects of WP and possible future products, providing a theoretical reference for the utilization and development of oil crop waste.

RSM-based Model to Predict Optimum Fermentation Conditions for Soluble Expression of the Antibody Fragment Derived from 4D5MOC-B Humanized Mab in SHuffle™ T7 E. coli

Overexpression of the EpCAM in epithelial-derived neoplasms makes this receptor a promising target in antibody-based therapy. Due to the lack of N-glycosylation, Escherichia coli (E. coli) seems to be the most appropriate choice for the expression of antibody fragments. However, developing a robust and cost-effective process that produces consistent therapeutic proteins from inclusion bodies is a major challenge. Undoubtedly, it can be circumvented by the soluble expression of these proteins. Utilization of numerous genetically modified hosts and optimization of cultivation conditions are two effective approaches widely used to overcome the insolubility problem. Due to the cytoplasmic expression of DsbC and the ability to the correct formation of disulfide bonds, the Shuffle™ T7 strain can be a suitable host for the soluble production of recombinant proteins. Here, Box-Behnken design (BBD)- Response surface methodology (RSM) modeling was employed to develop optimized culture conditions for 4D5MOC-B scFv fragment production in SHuffle™ T7 strain while solubility and production level were considered as responses. Although both responses were significantly influenced by post-induction temperature, cell density at induction time, and IPTG concentration, the temperature had the largest effect. The maximum experimental soluble protein obtained by adding 1 mM of IPTG into the M9 medium when the cell density reached 0.7 at 23 ᵒC was 693.56 µg/mL which was in good correlation with the predicted value of 720.742 µg/mL. Predictable total expression value was also experimentally verified. This strategy can be scaled-up for the production of large amounts of scFvs from SHuffle™ T7 E. coli to facilitate their potential applications as therapeutic and diagnostic agents.

Recent advances on protein separation and purification methods

Protein, as the material basis of vita, is the crucial undertaker of life activities, which constitutes the framework and main substance of human tissues and organs, and takes part in various forms of life activities in organisms. Separating proteins from biomaterials and studying their structures and functions are of great significance for understanding the law of life activities and clarifying the essence of life phenomena. Therefore, scientists have proposed the new concept of proteomics, in which protein separation technology plays a momentous role. It has been diffusely used in the food industry, agricultural biological research, drug development, disease mechanism, plant stress mechanism, and marine environment research. In this paper, combined with the recent research situation, the progress of protein separation technology was reviewed from the aspects of extraction, precipitation, membrane separation, chromatography, electrophoresis, molecular imprinting, microfluidic chip and so on.

Biovalorisation of crude glycerol and xylose into xylitol by oleaginous yeast Yarrowia lipolytica

Background

Xylitol is a commercially important chemical with multiple applications in the food and pharmaceutical industries. According to the US Department of Energy, xylitol is one of the top twelve platform chemicals that can be produced from biomass. The chemical method for xylitol synthesis is however, expensive and energy intensive. In contrast, the biological route using microbial cell factories offers a potential cost-effective alternative process. The bioprocess occurs under ambient conditions and makes use of biocatalysts and biomass which can be sourced from renewable carbon originating from a variety of cheap waste feedstocks.

Result

In this study, biotransformation of xylose to xylitol was investigated using Yarrowia lipolytica, an oleaginous yeast which was firstly grown on a glycerol/glucose for screening of co-substrate, followed by media optimisation in shake flask, scale up in bioreactor and downstream processing of xylitol. A two-step medium optimization was employed using central composite design and artificial neural network coupled with genetic algorithm. The yeast amassed a concentration of 53.2 g/L xylitol using pure glycerol (PG) and xylose with a bioconversion yield of 0.97 g/g. Similar results were obtained when PG was substituted with crude glycerol (CG) from the biodiesel industry (titer: 50.5 g/L; yield: 0.92 g/g). Even when xylose from sugarcane bagasse hydrolysate was used as opposed to pure xylose, a xylitol yield of 0.54 g/g was achieved. Xylitol was successfully crystallized from PG/xylose and CG/xylose fermentation broths with a recovery of 39.5 and 35.3%, respectively.

Conclusion

To the best of the author’s knowledge, this study demonstrates for the first time the potential of using Y. lipolytica as a microbial cell factory for xylitol synthesis from inexpensive feedstocks. The results obtained are competitive with other xylitol producing organisms.

Application of experimental designs and response surface methods in screening and optimization of reverse micellar extraction

Reverse micellar extraction (RME) has emerged as a versatile and efficient tool for downstream processing (DSP) of various biomolecules, including structural proteins and enzymes, due to the substantial advantages over conventional DSP methods. However, the RME system is a complex dependency of several parameters that influences the overall selectivity and performance of the RME system, hence this justifies the need for optimization to obtain higher possible extraction results. For the last two decades, many experimental design strategies for screening and optimization of RME have been described in literature. The objective of this article is to review the use of different experimental designs and response surface methodologies that are currently used to screen and optimize the RME system for various types of biomolecules. Overall, this review provides the rationale for the selection of appropriate screening or optimization techniques for the parameters associated with both forward and backward extraction during the RME of biomolecules.

Glucose-methanol-based fed-batch fermentation for the production of recombinant human interferon gamma (rhIFN-γ) and evaluation of its antitumor potential

Squamous cell carcinoma (SCC) is nonmelanoma skin cancer, which is very common in patients having T-cell immunosuppressant drugs. Anticancerous agents such as cytokines showed effective response on SCC. Human interferon-gamma (hIFN-γ), a type II cytokines, are having potent antiproliferative and immunomodulatory effects. In the current study, the fed-batch cultivation of recombinant Pichia pastoris was carried out, and its effect on cell biomass production, recombinant human interferon-gamma (rhIFN-γ) production, and the overflow metabolites was estimated. P. pastoris GS115 strain coexpressed with 6-phosphogluconolactonase (SOL3) and ribulose-phosphate 3-epimerase (RPE1) gene (GS115/rhIFN-γ/SR) resulted in 60 mg L^-1 of rhIFN-γ production, which was twofold higher as compared with the production from GS115/rhIFN-γ strain. The antiproliferative potential of rhIFN-γ was examined on the human squamous carcinoma (A431) cell lines. Cells treated with 80 ng mL^-1 of rhIFN-γ exhibited 50% growth inhibition by enhancing the production of intracellular reactive oxygen species levels and disrupting membrane integrity. Our findings highlight a state of art process development strategy for the high-level production of rhIFN-γ and its potential application as a therapeutic drug in SCC therapy.

Accurate and cost-effective prediction of HBsAg titer in industrial scale fermentation process of recombinant Pichia pastoris by using neural network based soft sensor

In the current work, the attempt was made to apply best-fitted artificial neural network (ANN) architecture and the respective training process for predicting final titer of hepatitis B surface antigen (HBsAg), produced intracellularly by recombinant Pichia pastoris Mut⁺ in the commercial scale. For this purpose, in large-scale fed-batch fermentation, using methanol for HBsAg induction and cell growth, three parameters of average specific growth rate, biomass yield, and dry biomass concentration-in the definite integral form with respect to fermentation time-were selected as input vectors; the final concentration of HBsAg was selected for the ANN output. Used dataset consists of 38 runs from previous batches; feed-forward ANN 3:5:1 with training algorithm of backpropagation based on a Bayesian regularization was trained and tested with a high degree of accuracy. Implementing the verified ANN for predicting the HBsAg titer of the five new fermentation runs, excluded from the dataset, in the full-scale production, the coefficient of regression and root-mean-square error were found to be 0.969299 and 2.716774, respectively. These results suggest that this verified soft sensor could be an excellent alternative for the current relatively expensive and time-intensive analytical techniques such as enzyme-linked immunosorbent assay in the biopharmaceutical industry.

Soluble expression of IGF1 fused to DsbA in SHuffle™ T7 strain: optimization of expression and purification by Box-Behnken design

Production of insulin-like growth factor 1 (IGF1) in Escherichia coli mostly results in the formation of inclusion bodies. In the present study, IGF1 was fused to disulfide bond oxidoreductase A (DsbA) and expressed in SHuffle™ T7 strain, in order to obtain correctly folded protein. Soluble expression and IMAC purification of DsbA-IGF1 were optimized by applying the Box-Behnken design of response surface methodology. The optimization greatly increased concentration of soluble protein from 317 to 2600 mg/L, and IMAC yield from 400 to 1900 mg/L. Results of ANOVA showed induction OD600 and temperature had significant effects on the soluble protein expression while isopropyl-β-d thiogalactoside, in the concentrations tested, displayed no significant effect. Moreover, the three parameters of the binding buffer including, pH, concentration of NaCl, and imidazole displayed significant effects on the IMAC yield. Then, purified DsbA-IGF1 was cleaved by human rhinovirus 3C protease, and authentic IGF1 was obtained in flow through of a subtractive IMAC. Final polishing of the protein by reversed-phase HPLC yielded IGF1 with purity of 96%. The quality attributes of purified IGF1 such as purity, identity, molecular size, molecular weight, secondary structure, and biological activity were assessed and showed to be comparable to the standard IGF1. The final yield of purified IGF1 was estimated to be 120 ± 18 mg from 1 L of the culture. Our results demonstrated a simple and easily scalable strategy for production of large amounts of bioactive IGF1 by rational designing soluble protein expression, and further optimization of expression and purification methods.

Cationic reverse micellar based purification of recombinant glutaminase free L-asparaginase II of Bacillus subtilis WB800N from fermentation media

Reverse micellar extraction (RME), a liquid-liquid based separation is a versatile tool for protein purification. A statistical approach was employed for the purification of recombinant glutaminase free anti-cancerous enzyme viz., l-asparaginase II to evaluate the effects of RME in current study. The cationic system (CTAB/iso-octane/hexanol/butanol) was used in RME to optimize both forward and backward protein extraction efficiency. By adapting Taguchi's orthogonal array (OA), maximum forward extraction efficiency (FEE) of 86.98% with 84.82% enzyme activity recovery and 1.04 times purification fold achieved with the optimized parameters. Under the optimal levels, the back extraction efficiency (BEE) was observed to be 96.97% with 93.07% enzyme activity recovery and 1.38 times purification fold. Further, mass transfer kinetic studies of RME indicated the mass transfer coefficients of forward and backward extraction to be 0.049 min^-1 and 0.036 min^-1 respectively.