Optimized extraction of polygalacturonase from Aspergillus aculeatus URM4953 by aqueous two-phase systems PEG/Citrate

Extraction of collagenolytic proteases from Aspergillus heteromorphus URM 0269 in an aqueous two-phase system for application in collagen hydrolysis

Collagenolytic proteases produced by Aspergillus heteromorphus URM0269 were extracted using a PEG/sulfate aqueous two-phase system (ATPS). A 23 factorial design was performed to analyze the independent variables: PEG molar mass (MPEG), PEG concentration (CPEG), and sulfate concentration (Csulf). The extracted proteases were also evaluated for their optimum pH and stability at different pH levels (4.0 - 11.0) after 20 h of incubation. Collagen was extracted from mutton snapper (Lutjanus analis) skin using acetic acid (0.5 mol L-1). The enzyme was preferentially partitioned to the PEG-rich phase (K > 1), whose highest purification factor and recovery (PF = 6.256 and Y = 404.432%) were obtained under specific conditions: MPEG 8000 g.mol-1, CPEG 30%, Csulf 10%. The ATPS extraction provided an enzymatic activity range of pH 7.0 - 11.0, exhibiting greater stability compared to the crude extract. Approximately 80% of protease activity was maintained after 20 hours of incubation at all analyzed pH levels, except pH 11.0. Collagen extraction from L. analis skin yielded 8.056%, and both crude extract samples and ATPS-derived samples successfully hydrolyzed the extracted collagen, reaching peak hydrolysis after 36 hours of treatment. These findings demonstrate the feasibility of extracting highly purified and active proteases capable of hydrolyzing L. analis collagen.

Purification and characterization of fibrinolytic protease from Streptomyces parvulus by polyethylene glycol-phosphate aqueous two-phase system

Fibrinolytic proteases are a promising alternative in the pharmaceutical industry, they are used in the treatment of cardiovascular diseases, especially thrombosis. Microorganisms are the most interesting source of fibrinolytic proteases. The aim of this study was the production of fibrinolytic protease from Streptomyces parvulus DPUA 1573, the recovery of the protease by aqueous two-phase system and partial biochemical characterization of the enzyme. The aqueous two-phase system was performed according to a 24-full factorial design using polyethylene glycol molar mass, polyethylene glycol concentration, citrate concentration and pH as independent variables. It was analyzed the effect of different ions, surfactants, inhibitors, pH and temperature on enzyme activity. The best conditions for purifying the enzyme were 17.5% polyethylene glycol 8,000, 15% Phosphate and pH 8.0, it was obtained a partition coefficient of 7.33, a yield of 57.49% and a purification factor of 2.10-fold. There was an increase in enzyme activity in the presence of Fe2+ and a decrease in the presence of $\beta$-Mercaptoethanol, phenylmethylsulfonyl fluoride and Iodoacetic acid. The optimum pH was 7.0 and the optimum temperature was 40 ºC. The purified protease exhibited a molecular mass of 41 kDa. The fibrinolytic protease from Streptomyces parvulus proved to be a viable option for the development of a possible drug with fibrinolytic action.

Valorisation of food agro-industrial by-products: From the past to the present and perspectives

Food agro-industrial by-products mainly include peels, seeds, stems, bagasse, kernels, and husk, derived during food processing. Due to their overproduction and the lack of sustainable management, such by-products have been conventionally rejected and wasted in landfills, being the principal strategy for their treatment, but nowadays, this strategy has been associated with several environmental, social and economic issues. Hence, we focused on the use of different consolidated biotechnological processes and methodologies as suitable strategies for food by-products management and valorisation, highlighting them as potential bioresources because they still gather high compositional and nutritional value, owing to their richness in functional and bioactive molecules with human health benefits. Food by-products could be utilised for the development of new food ingredients or products for human consumption, promoting their integral valorisation and reincorporation to the food supply chain within the circular bioeconomy concept, creating revenue streams, business and job opportunities. In this review, the main goal was to provide a general overview of the food agro-industrial by-products utilised throughout the years, improving global sustainability and human nutrition, emphasising the importance of biowaste valorisation as well as the methodologies employed for the recovery of value-added molecules.

Primary recovery of hyaluronic acid produced in Streptococcus equi subsp. zooepidemicus using PEG-citrate aqueous two-phase systems

Given its biocompatibility, rheological, and physiological properties, hyaluronic acid (HA) has become a biomaterial of increasing interest with multiple applications in medicine and cosmetics. In recent decades, microbial fermentations have become an important source for the industrial production of HA. However, due to its final applications, microbial HA must undergo critical and long purification processes to ensure clinical and cosmetic grade purity. Aqueous two-phase systems (ATPS) have proven to be an efficient technique for the primary recovery of high-value biomolecules. Nevertheless, their implementation in HA downstream processing has been practically unexplored. In this work, polyethylene glycol (PEG)–citrate ATPS were used for the first time for the primary recovery of HA produced with an engineered strain of Streptococcus equi subsp. zooepidemicus. The effects of PEG molecular weight (MW), tie-line length (TLL), volume ratio (V_R), and sample load on HA recovery and purity were studied with a clarified fermentation broth as feed material. HA was recovered in the salt-rich bottom phase, and its recovery increased when a PEG MW of 8000 g mol⁻¹ was used. Lower V_R values (0.38) favoured HA recovery, whereas purity was enhanced by a high V_R (3.50). Meanwhile, sample load had a negative impact on both recovery and purity. The ATPS with the best performance was PEG 8000 g mol⁻¹, TLL 43% (w/w), and V_R 3.50, showing 79.4% HA recovery and 74.5% purity. This study demonstrated for the first time the potential of PEG–citrate ATPS as an effective primary recovery strategy for the downstream process of microbial HA.

Extraction and purification of Aspergillus tamarii β-fructofuranosidase with transfructosylating activity using aqueous biphasic systems (PEG/phosphate) and magnetic field

β-fructofuranosidases (FFases) are enzymes involved in sucrose hydrolysis and fructo-oligosaccharides' production which are of great interest for the food industry. FFase from Aspergillus tamarii URM4634 was extracted using PEG/Phosphate Aqueous Biphasic Systems (ABS), and the impact of magnetic field on the extraction behavior was evaluated. A 2⁴-full experimental design was employed to study the influence of molar mass of PEG, concentrations of PEG and phosphate and pH on the selected response variables, i.e., partition coefficient (K), purification factor (PF), activity yield (Y) and selectivity (S). The influence of magnetic field during partition and NaCl concentration on the same responses was also studied. The best results of FFase extraction without magnetic field (K = 0.50, PF = 4.05, Y = 72.66% and S = 0.06) were observed at pH 8.0 using 12.5% (w/w) PEG 400 and 25% (w/w) NaH₂PO₄/K₂HPO₄. Application of the magnetic field allowed improving the performance, with the best results being obtained at the longest distance between magnets (lowest magnetic field) and absence of NaCl (K = 0.93, PF = 4.22, Y = 83.79% and S = 0.09). The outcomes obtained demonstrate that ABS combination with low intensity magnetic field can be used as an efficient FFase pre-purification method.

Smartphone-based competitive immunoassay for quantitative on-site detection of meat adulteration

Rapid, sensitive, and portable analytical methods for on-site inspection of food fraud are now an urgent requirement to ensure food quality and satisfy the ethnic considerations of consumers. Hence, for the first time, a colorimetric smartphone-based immunoassay was developed for the on-site detection of pork adulteration in meat. In detail, the immunoassay was based on a competitive strategy in which immobilized standard porcine IgG competed with the target porcine IgG extracted in a single step from meat samples. The parameters involved in each step of the immunoassay conception and the digital colorimetric detection were carefully investigated and optimized. Using polystyrene microplates as ready-to-use stable and portable immunoplatforms, TMB as chromogenic substrate, smartphone as signal readout, and Image J software for image processing; the developed immunoassay was able to detect as low as 0.01% of pork in meat mixtures in a total assay time of 30 min. The selectivity of the immunoassay was evaluated for different meat species, and it was shown to selectively respond only to pork. Furthermore, excellent stability of the prepared immunological platform was demonstrated under extreme temperature conditions (50 °C), which confirms its high portability potential for in situ quantification of pork, while being relatively cost effective and non-laborious. The developed method also provides great precision (RSD < 6%) and accuracy (relative error< 6%). Given the universal use of smartphones as portable and affordable devices, such format of immunoassay could be a promising approach for rapid and sensitive real-time monitoring of food fraud.

Effective separation of prolyl endopeptidase from Aspergillus Niger by aqueous two phase system and its characterization and application

Aspergillus niger prolyl endopeptidase (An-PEP) has become a research focus because of its advantages in specifically cleaving the C-terminal peptide bond of proline residues, especially it was an industrial food-grade acidic PEP. Aqueous two-phase system (ATPS) was first applied for separating An-PEP from fermentation broth. Via response surface method (RSM) experiment, an effectively separation of An-PEP was achieved by ATPS containing27% (w/w) ethanol and 14.5% (w/w) (NH₄)₂SO₄ at pH 6.0 with the recovery of 90.29 ± 0.23% and purification coefficient of 15.35 ± 0.30. The purified An-PEP was characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), fourier transform infrared (FTIR) and fluorescence spectrometry. The optimum temperature and pH of An-PEP were 40 °C and 4.5-5.0, respectively. An-PEP was activated and stabilized by Ca²⁺ but inhibited by Fe³⁺. The enzymatic application of purified An-PEP was evaluated by hydrolyzing egg white protein (EWP) to prepare bioactive peptides. The obtained hydrolysates had good scavenging ability of OH and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radicals, angiotensin converting enzyme (ACE) inhibitory activity and anti-gout activity. This research realized a low-cost, high-efficiency and simple separation technology of An-PEP and provided a broader idea for the preparation of bioactive peptides and the application of An-PEP.

Purification of a lectin from Cratylia mollis crude extract seed by a single step PEG/phosphate aqueous two-phase system

The partitioning and purification of lectins from the crude extract of Cratylia mollis seeds (Cramoll 1,4) was investigated in aqueous two-phase systems (ATPS). A factorial design model (2⁴) was used to evaluate the influence of polyethylene glycol (PEG) molar mass (1500-8000 g/mol), PEG concentration (12.5-17.5% w/w), phosphate (10-15% w/w) concentration, and pH (6-8) on the differential partitioning, purification factor, and yield of the lectin. Polymer and salt concentration were the most important variables affecting partition of lectin and used to find optimum purification factor by experimental Box-Behnken design together with the response surface methodology (RSM). ATPS showed best conditions composed by 13.9% PEG1500, 15.3% phosphate buffer at pH 6, which ensured purification factor of 4.70. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed a single band of protein with 26.1 kDa. Furthermore, results demonstrated a thermostable lectin presenting activity until 60 °C and lost hemagglutinating activity at 80 °C. According to the obtained data it can be inferred that the ATPS optimization using RSM approach can be applied for recovery and purification of lectins.

Management of Fruit Industrial By-Products-A Case Study on Circular Economy Approach

The management of industrial fruit by-products is important not only to decrease the volume of food waste accumulated in the landfills but also to develop strategies through reuse with the purpose to valorise and add economic value. The disposal of food waste leads to different global issues in different sectors, such as social, environmental and economical. These by-products represent a rich source of valuable compounds (polyphenols) with high antioxidant activity, which can be extracted through biotechnological methodologies for future industrial applications. In this context, the management of fruit by-products is challenged to move from a linear economy to a circular economy. Therefore, the purpose of this review is to provide a critical view of an integrated valorisation of fruit by-products to overcome a global issue, via the production of antioxidant extracts with high economic value. A case study of pineapple processing industrialization in a circular economy is explored and discussed.