Genomic analysis revealed conserved acid tolerance mechanisms from native micro-organisms in fermented feed.

AIMS: Fermented feed is an agricultural practice used in many regions of the world to improve the growth performance of farm animals. This study aimed to identify and evaluate the lactic acid bacteria and yeast involved in the production of fermented feed. METHODS AND RESULTS: We isolated and described two micro-organisms from autochthonous microbiota origin present in a regional feed product, Lactobacillus paracasei IBR07 (Lacticaseibacillus paracasei) and Kazachstania unispora IBR014 (Saccharomyces unisporum). Genome sequence analyses were performed to characterize both micro-organisms. Potential pathways involved in the acid response, tolerance and persistence were predicted in both genomes. Although L. paracasei and K. unispora are considered safe for animal feed, we analysed the presence of virulence factors, antibiotic resistance and pathogenicity islands. Furthermore, the Galleria mellonella model was used to support the safety of both isolates. CONCLUSIONS: We conclude that IBR07 and IBR014 strains are good candidates to be used as starter cultures for feed fermentation. SIGNIFICANCE AND IMPACT OF THE STUDY: The data presented here will be helpful to explore other biotechnological aspects and constitute a starting point for further studies to establish the consumption benefit of fermented feed in farm animal production.

An integrated approach to the sustainable production of xylanolytic enzymes from Aspergillus niger using agro-industrial by-products.

Xylanolytic enzymes were produced by Aspergillus niger NRRL3 grown on agro-industrial by-products obtained from the processing of wheat flour without pretreatment. Significant parameters for xylanase production were screened and optimized. The xylanolytic activity obtained in the optimized extract was 138.3 ± 2.6 U/mL, higher than the activity obtained in an unoptimized medium (14.5 ± 0.3 U/mL) in previous work. The optimized fermentation process was performed in a successful 40-fold scale-up. The optimized enzymatic extract obtained was characterized by LC-MS. Nine enzymes were identified as constituents of the xylanolytic complex. Moreover, the xylanolytic enzymes were stable until 60 °C and over a broad range of pH. Sodium, calcium, cobalt and manganese had no inhibitory effect, meanwhile 1% w/v polyvinylpyrrolidone and 1% w/v dextran increased the xylanolytic activity. The saccharification efficiency was evaluated and the surface morphology of the lignocellulosic substrate was monitored by using scanning electron microscopy (SEM). The synergistic combination of the extracted (o purified) xylanolytic enzymes permitted a higher xylan conversion beneficial for diverse applications, such as bioethanol production. Thus, these agroindustrial by-products can be used within the framework of a circular economy, rendering an added value bioproduct, which is reused in the industry.

Interaction between trypsin and alginate: An ITC and DLS approach to the formation of insoluble complexes.

Trypsin is a protease widely used in several industrial areas for leather and meat softening and to produce enzymatic detergents, among others applications. The high demand for this enzyme has motivated the development of purification, stabilization and immobilization methods Formation of insoluble complexes between proteins and polyelectrolytes is a methodology that may include these features. The aim of this paper is to give evidence for a novel methodology that combines precipitation of the insoluble trypsin-alginate complex and hydrophobic interaction chromatography. This methodology allows the interaction between trypsin and alginate and their separation when necessary. It could be applied to isolation, stabilization and/or immobilization of trypsin. Isothermal titration calorimetry experiments showed that 232µmol of trypsin interacts electrostatically with 1g of alginate to form an insoluble complex that can be separated from soluble contaminants by decantation. Dynamic light scattering experiments confirmed the calorimetric results and allowed measuring the Rh of the soluble complex at pH 3.5 (185nm). When the optimal conditions were applied to precipitate commercially available trypsin, the recovery of the precipitation was around 92%. Finally, hydrophobic interaction chromatography allowed separating alginate from trypsin in order to obtain a polymer-free enzyme.

Partitioning of xylanase from Thermomyces lanuginosus in PEG/NaCit aqueous two-phase systems: Structural and functional approach.

The structure and catalytic activity of xylanase from Thermomyces lanuginosus were studied in different media (containing polyethylene glycol -PEG- or salt) at different temperatures. The aim was to study how the native structure of the enzyme is affected to understand the partitioning behavior of xylanase in PEG/sodium citrate (PEG/NaCit) aqueous two-phase systems. The presence of PEGs of different molar masses slightly altered the native structure of xylanase, although its catalytic activity was not affected. All the polymers assayed protect the native structure (and catalytic activity) of xylanase against temperature, except for PEG1000. Surface hydrophobicity experiments showed that xylanase favorable interacts with PEGs. Partitioning experiments confirmed this result and demonstrated that PEG1000/NaCit is the best system to partition xylanase from Thermomyces lanuginosus, since the Kp was 17.7 ± 0.3.

Characterization of the Interaction Between Pancreatic Trypsin and an Enteric Copolymer as a Tool for Several Biotechnological Applications.

Protein-polyelectrolyte complexes are very interesting systems since they can be applied in many long-established and emerging areas of biotechnology. From nanotechnology to industrial processing, these complexes are used for many purposes: to build multilayer particles for biosensors; to entrap and deliver proteins for pharmaceutical applications; to isolate and immobilize proteins. The enteric copolymer poly(methacrylic acid-co-methyl methacrylate) 1:2 (MMA) has been designed for drug delivery although its chemical properties allow to use it for other applications. Understanding the interaction between trypsin and this polymer is very important in order to optimize the mechanism of formation of this complex for different biotechnological applications.The formation of the trypsin-MMA complex was studied by spectroscopy and isothermal titration calorimetry. Structural analysis of trypsin was carried out by catalytic activity assays, circular dichroism and differential scanning calorimetry. Isothermal titration calorimetry experiments showed that the insoluble complex contains 12 trypsin molecules per MMA molecule at pH 5 and they interact with high affinity to form insoluble complexes. Both electrostatic and hydrophobic forces are involved in the formation of the complex. The structure of trypsin is not affected by the presence of MMA, although it interacts with some domains of trypsin affecting its thermal denaturation as seen in the differential scanning calorimetry experiments. Its catalytic activity is not altered. Dynamic light scattering demonstrated the presence of a soluble trypsin-copolymer complex at pH 5 and 8. Turbidimetric assays show that the insoluble complex can be dissolved by low ionic strength and/or pH in order to obtain free native trypsin.

Optimization of pancreatic trypsin extraction in PEG/citrate aqueous two-phase systems.

Enzyme extraction using aqueous two-phase systems (ATPS) has been increasingly used as a primary recovery technique which integrates the clarification, concentration and partial purification of important biomolecules from their natural source in a single step. The goal of this work was to optimize the extraction of trypsin from pancreas homogenate with polyethylene glycol and sodium citrate (PEG/NaCit) ATPS by using the tools of experimental design. The variables NaCl concentration - added inert salt -, the top/bottom phase volume ratio - Vr - and the biomass loaded into the system - in percentage - were selected as the main factors in the trypsin extraction. The yield (%) and the purification factor of trypsin were considered the responses to be optimized. The central composite design and the response surface analysis proved to be suitable tools for a quick and efficient study. As a result, the optimal extraction conditions in PEG3350/NaCit system were 3.34% wt/wt for NaCl concentration, a biomass load which represented 9.30% wt/wt of the total ATPS mass and 6.37 top/bottom volume ratio giving a purification factor of 2.55 and a yield of 99.7% in top phase.

Bioseparation of papain from Carica papaya latex by precipitation of papain-poly (vinyl sulfonate) complexes.

The formation of insoluble complexes between enzymes and polyelectrolytes is a suitable technique for isolating these biomolecules from natural sources, because it is a simple and rapid technique that allows the concentration of the protein. This technique can be used in most purification protocols at the beginning of the downstream process. The aim of this investigation is to isolate papain from Carica papaya latex by precipitation of insoluble complexes between this enzyme and poly (vinyl sulfonate). The papain-poly (vinyl sulfonate) complex was insoluble at pH lower than 6, with a PVS/PAP stoichiometric ratio of 1:279. Ionic strength affected the complex formation. The presence of the polymer increased the enzymatic activity and protected the enzyme from autodegradation. The optimal conditions for the formation of insoluble papain-polyelectrolyte complex formation were applied to C. papaya latex and a high recovery was obtained (around 86%) and a purification factor around 2. This method can be applied as an isolation method of papain from C. papaya latex or as a first step in a larger purification strategy.

Pancreatic serine protease extraction by affinity partition using a free triazine dye.

Affinity partitioning combines the partitioning behavior of biological macromolecules in aqueous two-phase systems with the principle of biorecognition. Among the numerous substances that have been evaluated as ligands, the reactive dyes constitute a group of low cost textile dyes which have proved to act as biomimetic ligands for many enzymes. The ability of reactive yellow 2 (RY2) to interact with trypsin (TRP) and chymotrypsin (ChTRP) and its behavior in aqueous two-phase systems formed by polyethylene glycol (PEG) and sodium citrate (NaCit) - were investigated. Different variables such as PEG molecular weight, tie line length and dye concentration were analyzed. RY2 showed to bind specifically to both TRP and ChTRP with affinity constants near to 10(3)M(-1). Its partition equilibrium is practically displaced to the top phase in systems formed by PEG of different molecular weight. Addition of this dye to PEG 8000/NaCit systems until a final concentration of 0.196% (w/w) induced an increase in TRP and ChTRP partition coefficients of at least 2 times over that in the absence of the ligand. These findings demonstrate that RY2 fulfils all the requirements to be considered as an affinity ligand in aqueous two-phase partitioning of TRP and ChTRP.

Analysis of the interactions between Eudragit® L100 and porcine pancreatic trypsin by calorimetric techniques.

Flexible-chain polymers with charge (polyelectrolytes) can interact with globular proteins with a net charge opposite to the charge of the polymers forming insoluble complexes polymer-protein. In this work, the interaction between the basic protein trypsin and the anionic polyelectrolyte Eudragit(®) L100 was studied by using isothermal calorimetric titrations and differential scanning calorimetry. Turbidimetric assays allowed determining that protein-polymer complex was insoluble at pH below 5 and the trypsin and Eudragit(®) L100 concentrations required forming the insoluble complex. DSC measurements showed that the T(m) and denaturalization heat of trypsin increased in the polymer presence and the complex unfolded according to a two-state model. ΔH° and ΔS° binding parameters obtained by ITC were positives agree with hydrophobic interaction between trypsin and polymer. However, ionic strength of 1.0M modified the insoluble complex formation. We propose a mechanism of interaction between Eudragit(®) L100 and trypsin molecules that involves both hydrophobic and electrostatic interactions. Kinetic studies of complex formation showed that the interaction requires less than 1 min achieving the maximum quantity of complex. Finally, a high percentage of active trypsin was precipitated (approximately 76% of the total mass of protein). These findings could be useful in different protocols such as a protein isolation strategy, immobilization or purification of a target protein.

Extraction of trypsin from bovine pancreas by applying polyethyleneglycol/sodium citrate aqueous two-phase systems.

The goal of this work was to determine the optimal conditions for separating trypsin (TRP) from alpha-chymotrypsin (ChTRP) and to apply them for trypsin purification from bovine pancreas by liquid-liquid extraction with polyethyleneglycol/sodium citrate (PEG/NaCit) aqueous two-phase systems. Partitioning behaviours of TRP and ChTRP are demonstrated to be very sensitive to variables such as PEG molecular weight, pH and tie line length. Aqueous two-phase systems (ATPSs) formed by PEG of MW 3350 and NaCit pH 5.20 showed the best separation capability. The addition of NaCl up to a final concentration of 7% (w/w) and the decrease of top/bottom volume ratio to 0.1 led to the recovery of 60% of pancreatic TRP in a concentrated form in the top phase with a 3-fold purification. Biomass presence up to 25% (w/w) of the total system mass did not affect significantly yield and purification parameters.

Partition features and renaturation enhancement of chymosin in aqueous two-phase systems.

Aqueous two-phase systems of polyethylene glycol (molecular mass 1450, 3350 and 6000)-phosphate and polyethylene-polypropylene oxide (molecular mass 8400)-maltodextrin systems were used in order to study the partition features of recombinant chymosin from inclusion bodies. These systems in the presence of 8M urea were used for the solubilization of inclusion bodies containing recombinant chymosin and for the oxidative renaturation of this protein. Recombinant chymosin showed to be partitioned in favour of the top phase in all studied systems with a partition coefficient between 4 and 6. The recovery of the chymosin biological activity was 32% in the polyethylene-polypropylene oxide, while in the polyethylene glycol-phosphate the recovery was 50-59%. The results indicate that the liquid-liquid extraction would be an adequate tool able to isolate and concentrate chymosin from inclusion bodies with a yield of biological activity higher than that obtained from the standard method (43%).

Partitioning features of bovine trypsin and alpha-chymotrypsin in polyethyleneglycol-sodium citrate aqueous two-phase systems.

The partitioning of bovine trypsin and alpha-chymotrypsin--proteases of similar physico-chemical properties--in different polyethyleneglycol/sodium citrate aqueous two-phase systems was investigated. The effect of different factors such as polyethyleneglycol molecular weight, pH, tie line length, temperature and the presence of an inorganic salt on the protein partition coefficient were analysed. Both a decrease in PEG molecular weight and an increase in pH led to a higher partition coefficient for both enzymes. Aqueous two-phase systems formed by PEG of molecular weight 3350 and citrate pH 5.2 showed the best separation capability which was enhanced in presence of sodium chloride 3%. The transfer of both proteins to the top phase was associated with negative enthalpic and entropic changes.

Relationship between the protein surface hydrophobicity and its partitioning behaviour in aqueous two-phase systems of polyethyleneglycol-dextran.

In order to develop possible correlations to predict partioning behaviour of proteins, five mammalian albumins (goat, bovine, equine, human and pig ones) with similar physico-chemical properties (molecular mass and isoelectrical point) were chosen. Evaluation of the relationship between hydrophobicity and partitioning coefficient (Kr) in polyethylenglycol-dextran (PEG-DxT500) systems formed by polyethyleneglycols of different molecular mass (3350, 6000 and 10,000) was investigated by estimating relative surface hydrophobicity (So) with a fluorescent probe, 1 anilino-8-naphthalene sulfonate. No relationship between Kr and So was found for systems formed by PEG3350, while aqueous two-phase systems with PEG6000 and PEG10,000 gave better correlations. The results obtained may be explained on the basis of an increase in the interaction between the latter PEGs and the protein due to their higher hydrophobic character which increases as the PEG molecular mass does so. In this way, systems with PEGs of higher molecular mass give the highest resolution to exploit hydrophobicity in partitioning.