Microbial phytase: Impact of advances in genetic engineering in revolutionizing its properties and applications

Myceliophthora thermophila as promising fungal cell factories for industrial bioproduction: From rational design to industrial applications

Myceliophthora thermophila stands out as a prominent fungal cell factory, garnering growing interest due to its distinctive traits advantageous. Currently, M. thermophila has been developed as an efficient cell factory, producing a variety of products from various raw materials. In this review, we firstly discuss the potential advantages of M. thermophila as a platform for metabolic engineering and industrial applications, with special emphasis on its physiological characteristics, the development of genetic modification techniques and tools, gene expression and regulation strategies. Then, the latest progress in industrial application of M. thermophila as microbial cell factory was systematically summarized, including biochemical synthesis platform, enzyme expression platform, antibody protein and vaccine production platform, bio-organic fertilizer production platform, and efficient enzyme element library. Finally, the current challenges of M. thermophila as a cell factory and its corresponding strategies are proposed, aiming to achieve green biomanufacturing of multiple products with higher efficiency.

Structural and Functional Characterization of Obesumbacterium proteus Phytase: A Comprehensive In-Silico Study

Phytate, also known as myoinositol hexakisphosphate, exhibits anti-nutritional properties and possesses a negative environmental impact. Phytase enzymes break down phytate, showing potential in various industries, necessitating thorough biochemical and computational characterizations. The present study focuses on Obesumbacterium proteus phytase (OPP), indicating its similarities with known phytases and its potential through computational analyses. Structure, functional, and docking results shed light on OPP's features, structural stability, strong and stable interaction, and dynamic conformation, with flexible sidechains that could adapt to different temperatures or specific functions. Root Mean Square fluctuation (RMSF) highlighted fluctuating regions in OPP, indicating potential sites for stability enhancement through mutagenesis. The systematic approach developed here could aid in enhancing enzyme properties via a rational engineering approach. Computational analysis expedites enzyme discovery and engineering, complementing the traditional biochemical methods to accelerate the quest for superior enzymes for industrial applications.

Recent advances in phytase thermostability engineering towards potential application in the food and feed sectors

This review comprehensively examines the advancements in engineering thermostable phytase through genetic modification and immobilization techniques, focusing on developments from the last seven years. Genetic modifications, especially protein engineering, have enhanced enzyme's thermostability and functionality. Immobilization on various supports has further increased thermostability, with 50-60 % activity retention at higher temperature (more than 50 °C). In the food industry, phytase is used in flour processing and bread making, reducing phytate content by around 70 %, thereby improving nutritional value and mineral bioavailability. In the feed industry, it serves as a poultry feed additive, breaking down phytates to enhance nutrient availability and feed efficiency. The enzyme's robustness at high temperatures makes it valuable in feed processing. The integration of microbial production of phytase with genetically engineered strains followed by carrier free immobilization represents a synergistic approach to fortify enzyme structure and improve thermal stability. These advancement in the development of phytase enzyme capable of withstanding high temperatures, thereby pivotal for industrial utilization.

Quinoa sourdough fermented with Lactiplantibacillus plantarum CRL 1964, a powerful tool to enhance the nutritional features of quinoa snacks

The remarkable nutritional attributes and potential health advantages of quinoa make it an important candidate for developing innovative ready-to-eat food products. This work aimed to develop a functional ready-to-eat snack based on quinoa sourdough fermented by Lactiplantibacillus (L.) plantarum CRL 1964. Phytate, phosphates, and soluble mineral content (Fe, Mn, Zn, Mg, Ca, and P) were determined in snacks formulated with sourdough and control doughs. An in vitro digestion model was performed on quinoa snacks to assess their mineral bioaccessibility and dialyzability. Phytate content was significantly lower (ca. 42.3%) while phosphates were higher (ca. eightfold) in quinoa-based sourdough and sourdough-based snacks (S1964) than in controls. Soluble minerals were higher (10.2%-32.0%) in S1964 than in controls. Mineral bioaccessibility and mineral dialyzability were also higher (ca. 24.5%) among S1964 and control snacks. The developed quinoa snack made from sourdough fermented by L. plantarum CRL 1964 had less phytate concentration and high bioaccessibility of minerals. These findings underscore the relevance of this innovative technology in creating food products that are not only highly nutritious but also represent a valuable contribution to the market of healthy foods. PRACTICAL APPLICATION: In this study, a novel snack based on quinoa sourdough with improved nutritional properties was developed. The addition of quinoa sourdough fermented by Lactiplantibacillus plantarum CRL 1964 to the preparation of quinoa snacks resulted in a product with a lower concentration of phytate and a higher content of phosphates and minerals (soluble, bioaccessible, and dialyzable). These results underline the efficacy of the new snack as a promising alternative to conventional mineral fortification methods. This innovative approach holds promise for addressing nutritional deficiencies and the demand for healthy snack options in today's market.

Achieving thermostability of a phytase with resistance up to 100 °C

The development of enzymes with high-temperature resistance up to 100 °C is of significant and practical value in advancing the sustainability of industrial production. Phytase, a crucial enzyme in feed industrial applications, encounters challenges due to its limited heat resistance. Herein, we employed rational design strategies involving the introduction of disulfide bonds, free energy calculation, and B-factor analysis based on the crystal structure of phytase APPAmut4 (1.90 Å), a variant with enhanced expression levels derived from Yersinia intermedia, to improve its thermostability. Among the 144 variants experimentally verified, 29 exhibited significantly improved thermostability with higher t1/2 values at 65 °C. Further combination and superposition led to APPAmut9 with an accumulation of five additional pairs of disulfide bonds and six single-point mutation sites, leading to an enhancement in its thermostability with a t1/2 value of 256.7 min at 65 °C, which was more than 75-fold higher than that of APPAmut4 (3.4 min). APPAmut9 exhibited a T50 value of 96 °C, representing a substantial increase of 40.9 °C compared to APPAmut4. Notably, approximately 70% of enzyme activity remained intact after exposure to boiling water at 100 °C for a holding period of 5 min. Significantly, these advantageous modifications were strategically positioned away from the catalytic pocket where enzymatic reactions occur to ensure minimal compromise on catalytic efficiency between APPAmut9 (11,500 ± 1100/mM/s) and APPAmut4 (12,300 ± 1600/mM/s). This study demonstrates the feasibility of engineering phytases with resistance to boiling using rational design strategies.

Statistical optimized production of Phytase from Hanseniaspora guilliermondii S1 and studies on purification, homology modelling and growth promotion effect

This investigation was performed to obtain a promising phytase enzyme producing yeast. In this regard, the PSM was used to isolate the phytase-producing Hanseniaspora guilliermondii S1 (MG663578) from sugarcane juice. The SSF optimum conditions for phytase generation were optimized using (OVAT) one-variable-at-a-time strategy using both Box-Behnken design and shake flask method (g/100 ml: 0.05 yeast extract, 0.15 Peptone, 0.05 malt extract 0.50 dextrose, pH 5.8 and 28ᵒC). The protein model developed was shown to be adequate for phytase production (91% accuracy), with the greatest phytase productivity in shake flask with substrate jack fruit seed powder being 395 ± 0.43 U/ml compared to 365U/ml for the BBD projected value. Crude Phytase was partially purified with a protein recovery of 43%, revealing a molecular weight of 120 kDa. It had an enzyme kinetic value of Km 3.3 mM and a Vmax of 19.1 mol/min. The 3D structure of PhyS1 amino acid sequences (PhyS1. B99990002) was simulated using Modeler 9.23, and the validated result revealed that 86.7% were in the favored region by Ramachandran plot. The SAVES server verified the 3D PDB file as satisfactory, and the model (in.pdb format) was uploaded in the PMDB database with the accession number ID: PM0082974. At the lab level, Hanseniaspora guilliermondii S1 (MG663578) producing phytase exhibited successful plant growth promotion activity in Ragi - CO 19 (Eleusine coracana L.) and Rice -Navarai - IR 64 (Oryza sativa L.). As a result, a phytase-based formulation for sustainable agriculture must be developed and tested on a large scale in diverse geographical areas of agricultural lands to determine its effect and potential on plant development.

Microbial Phytases: Properties and Applications in the Food Industry

Microbial phytases are enzymes that break down phytic acid, an anti-nutritional compound found in plant-based foods. These enzymes which are derived from bacteria and fungi have diverse properties and can function under different pH and temperature conditions. Their ability to convert phytic acid into inositol and inorganic phosphate makes them valuable in food processing. The application of microbial phytases in the food industry has several advantages. Firstly, adding them to animal feedstuff improves phosphorus availability, leading to improved nutrient utilization and growth in animals. This also reduces environmental pollution by phosphorus from animal waste. Secondly, microbial phytases enhance mineral bioavailability and nutrient assimilation in plant-based food products, counteracting the negative effects of phytic acid on human health. They can also improve the taste and functional properties of food and release bioactive compounds that have beneficial health effects. To effectively use microbial phytases in the food industry, factors like enzyme production, purification, and immobilization techniques are important. Genetic engineering and protein engineering have enabled the development of phytases with improved properties such as enhanced stability, substrate specificity, and resistance to degradation. This review provides an overview of the properties and function of phytases, the microbial strains that produce them, and their industrial applications, focusing on new approaches.

Advances in immobilization of phytases and their application

The review describes the advances in the phytase immobilization for the past decade and their biotechnological applications. Different approaches for phytase immobilization are described including the process using organic and inorganic matrices and microbial cells, as well as nanostructures of various nature. Moreover, the immobilization of phytase-producing microbial cells and the use of cross-linked phytase aggregates have been under consideration. A detailed classification of various carriers for immobilization of phytases and the possibility of their applications are presented. A particular attention is drawn to a breakthrough approach of biotechnological significance to the design of microencapsulation of bacterial phytase from Obesumbacterium proteus in the recombinant extremophile of Yarrowia lipolytica.

Microbial engineering for the production and application of phytases to the treatment of the toxic pollutants: A review

Phytases are a group of digestive enzymes which are commonly used as feed enzymes. These enzymes are used exogenously in the feeds of monogastric animals thereby it improves the digestibility of phosphorous and thus reduces the negative impact of inorganic P excretion on the environment. Even though these enzymes are widely distributed in many life forms, microorganisms are the most preferred and potential source of phytase. Despite the extensive availability of the phytase-producing microbial consortia, only a few microorganisms have been known to be exploited at industrial level. The high costs of the enzyme along with the incapability to survive high temperatures followed by the poor storage stability are noted to be the bottleneck in the commercialization of enzymes. For this reason, besides the conventional fermentation approaches, the applicability of cloning, expression studies and genetic engineering has been implemented for the past few years to accomplish the abovesaid benefits. The site-directed mutagenesis as well as knocking out have also validated their prominent role in microbe-based phytase production with enhanced levels. The present review provides detailed information on recent insights on the modification of phytases through heterologous expression and protein engineering to make thermostable and protease-resistant phytases.

Conditioning of Feed Material Prior to Feeding: Approaches for a Sustainable Phosphorus Utilization

A circular phosphorus (P) bioeconomy is not only worthwhile for conserving limited mineral P reservoirs, but also for minimizing negative environmental impacts caused by human-made alterations. Although P is an essential nutrient, most of the P in concentrates based on cereals, legumes and oilseed byproducts is organically bound to phytate. The latter cannot be efficiently utilized by monogastric animals and is therefore diluted into the environment through the manure pathway. This review examines various strategies for improved P utilization in animals and reflects the respective limitations. The strategies considered include feeding of debranned feedstuffs, pre-germinated feed, co-feeding of phytase and feeding material with high native phytase activity. All these approaches contribute to an improved P bioavailability. However, about half of the organic P content continues to be excreted and therefore remains unused by the animals. Nevertheless, technologies for an efficient utilization of P from cereal-based feed already exist; however, these are not industrially established. Conditioning feed material prior to feeding fosters P-reduced feed; meanwhile, P bound to phytate can be recovered. Based on known techniques for P separation and solubilisation from cereal products and phytate conversion, potential designs for feed material conditioning processes are proposed and evaluated.

Dietary Phosphorus and Calcium Utilization in Growing Pigs: Requirements and Improvements

The sustainability of animal production relies on the judicious use of phosphorus (P). Phosphate, the mined source of agricultural phosphorus supplements, is a non-renewable resource, but phosphorus is essential for animal growth, health, and well-being. P must be provided by efficient and sustainable means that minimize the phosphorus footprint of livestock production by developing precise assessment of the bioavailability of dietary P using robust models. About 60% of the phosphorus in an animal's body occurs in bone at a fixed ratio with calcium (Ca) and the rest is found in muscle. The P and Ca requirements must be estimated together; they cannot be dissociated. While precise assessment of P and Ca requirements is important for animal well-being, it can also help to mitigate the environmental effects of pig farming. These strategies refer to multicriteria approaches of modeling, efficient use of the new generations of phytase, depletion and repletion strategies to prime the animal to be more efficient, and finally combining these strategies into a precision feeding model that provides daily tailored diets for individuals. The industry will need to use strategies such as these to ensure a sustainable plant-animal-soil system and an efficient P cycle.

A novel phytase from Citrobactergillenii: characterization and expression in Pichia pastoris (Komagataella pastoris)

The phyCg gene encoding a new phytase from Citrobacter gillenii was optimized, synthesized, cloned and expressed in Pichia pastoris. Analysis of the amino acid sequence of the enzyme showed that it belongs to the histidine acid phosphatase family. The amino acid sequence of the PhyCg phytase has the highest homology (73.49%) with a phytase sequence from Citrobacter braakii. The main characteristics for the purified recombinant phytase were established. The optimum pH and temperature were 4.5 and 50°C, respectively. The specific activity of the enzyme was 1577 U/mg. The Michaelis constant (Km) and the maximum reaction rate (Vmax) for sodium phytate were 0.185 mM and 2185 U/mg, respectively. The enzyme showed the pH and trypsin stability and had a high activity over a wide pH range.

Improved sensitivity, accuracy and prediction provided by a high-performance liquid chromatography screen for the isolation of phytase-harbouring organisms from environmental samples

HPLC methods are shown to be of predictive value for classification of phytase activity of aggregate microbial communities and pure cultures. Applied in initial screens, they obviate the problems of 'false-positive' detection arising from impurity of substrate and imprecision of methodologies that rely on phytate-specific media. In doing so, they simplify selection of candidates for biotechnological applications. Combined with 16S sequencing and simple bioinformatics, they reveal diversity of the histidine phosphatase class of phytases most commonly exploited for biotechnological use. They reveal contribution of multiple inositol-polyphosphate phosphatase (MINPP) activity to aggregate soil phytase activity, and they identity Acinetobacter spp. as harbouring this prevalent soil phytase activity. Previously, among bacteria MINPP was described exclusively as an activity of gut commensals. HPLC methods have also identified, in a facile manner, a known commercially successful histidine (acid) phosphatase enzyme. The methods described afford opportunity for isolation of phytases for biotechnological use from other environments. They reveal the position of attack on phytate by diverse histidine phosphatases, something that other methods lack.

Improved thermal stability of phytase from Yersinia intermedia by physical adsorption immobilization on amino-multiwalled carbon nanotubes

Phytase is used in poultry diets to hydrolyze and release of phytate-bound phosphorus. Immobilization on nanomaterials optimizes enzyme's thermal stability and reusability. This study aimed to immobilize the recombinant phytase from Yersinia intermedia on the surface of amino-multi-walled carbon nanotubes (amino-MWCNTs) by physical adsorption. For this, zeta potential measurement, FTIR spectroscopic analysis, scanning electron microscope (SEM), kinetic as well as thermodynamic parameters were used to characterize immobilized phytase on amino-MWCNTs. According to results, the optimum temperature of the immobilized phytase increased from 50 to 70 °C and also thermal and pH stability improved considerably. Moreover, immobilization led to an increase in the value of K_m and k_cat from 0.13 to 0.33 mM and 2220 to 2776 s^-1, respectively. In addition, the changes in activation energy of thermal inactivation (ΔE^#_{a (D)}), the free energy of thermal inactivation (ΔG^#_D) and the enthalpy of thermal inactivation (ΔH^#_D) for immobilized phytase increased by +11.05, +24.7 and +11.4 kj/mole, respectively, while the value of the change in the entropy of thermal inactivation (ΔS^#_D) decreased by - 0.04 kj/mole.K. Overall, our results showed that adsorption immobilization of phytase on amino-MWCNTs increases thermal, pH and storage stability as well as some of kinetic parameters.

A multistrategy approach for improving the expression of E. coli phytase in Pichia pastoris

Phytase is an additive in animal feed that degrades phytic acid in plant material, reducing feeding costs, and pollution from fecal phosphorus excretion. A multistrategy approach was adopted to improve the expression of E. coli phytase in Pichia pastoris. We determined that the most suitable signal peptide for phytase secretion was an α-factor secretion signal with an initial enzyme activity of 153.51 U/mL. Increasing the copy number of this gene to four increased phytase enzyme activity by 234.35%. PDI overexpression and Pep4 gene knockout increased extracellular phytase production by 35.33% and 26.64%, respectively. By combining favorable factors affecting phytase expression and secretion, the enzyme activity of the phytase-engineered strain was amplified 384.60% compared with that of the original strain. We also evaluated the potential for the industrial production of the engineered strain using a 50-L fed-batch fermenter and achieved a total activity of 30,246 U/mL after 180 h of fermentation.

Partial characterization and purification of phytase from Lactobacillus plantarum CRL1964 isolated from pseudocereals

Cereals and pseudocereals are a rich source of nutrients and trace elements, but their dietary bioavailability is low due to the presence of phytate (IP6), an antinutritional compound with the ability to chelate cations and proteins. Phytase is an enzyme that catalyzes the hydrolysis of IP6 and it is used as an additive improving the nutritional quality of grain-based foods. The aim of this study was to select lactic acid bacteria (LAB) isolated from pseudocereals with phytase activity, characterize their production and activity, and purify the enzyme. LAB strains isolated from grains and spontaneous sourdough of quinoa and amaranth were grown in the Man Rogosa and Sharpe medium where the inorganic phosphate (Pi) was replaced by 1% of IP6. Phytase activity was determined by measuring the Pi released from IP6. Phytase of Lactobacillus (L.) plantarum CRL1964 (PhyLP) showed the highest specific activity from 73 LAB evaluated. IP6 induces PhyLP production, which is at its maximum at the end of the exponential phase. PhyLP was thermostable and maintained its activity under acidic conditions. The enzymatic activity is stimulated by ethylenediaminetetraacetic acid, Co²⁺, and ascorbic acid. PhyLP was partially purified and showed a molecular mass of 55 kDa. L. plantarum CRL1964 and/or PhyLP have the potential to be included in the processing of cereal/pseudocereals based products for animal feed and/or the food industry improving its nutritional value.

A novel fungal beta-propeller phytase from nematophagous Arthrobotrys oligospora: characterization and potential application in phosphorus and mineral release for feed processing

Phytases are widely utilized in feed industry to increase the utilization of phosphorus, minerals, and amino acids for improvement of animal and human nutrition. At present, all known β-propeller phytases (BPP) have been generated from bacteria, particularly Bacillus. In this work we report for the first time a new fungal-derived BPP phytase. We identified a phytase highly differentially expressed only in the parasitic stage of a nematophagous fungus, Arhtrobotrys oliogospora, during the development of the 3D traps. We found that this phytase was homologous to the known bacterial BPP phytase, thus we referred the new phytase to Aophytase. The heterologous expression of codon-optimized Aophytase gene in Pichia pastoris was successfully investigated to yield recombinant Aophytase (r-Aophytase) with high specific enzyme activity of 74.71 U/mg, much higher than those of recombinant BPP phytases derived bacteria. The kinetic parameters of the r-Aophytase, the optimum pH and temperature, as well as the effects of surfactant, EDTA and different ions on its enzyme activity were further investigated. The potential utilization of r-Aophytase in feed processing was finally explored. We found that the optimal pH value was about 7.5, and the optimal temperature was 50 °C.; r-Aophytase significantly increased the release of inorganic phosphorus from soybean meal, and improved the release of soluble minerals from the durum wheat flour and finger millet flour. The findings indicate its potential utilization in the feed processing to ameliorate nutritional value of cereals and animal feed in the future.

Bioprocess for Production, Characteristics, and Biotechnological Applications of Fungal Phytases

Phytases are a group of enzymes that hydrolyze the phospho-monoester bonds of phytates. Phytates are one of the major forms of phosphorus found in plant tissues. Fungi are mainly used for phytase production. The production of fungal phytases has been achieved under three different fermentation methods including solid-state, semi-solid-state, and submerged fermentation. Agricultural residues and other waste materials have been used as substrates for the evaluation of enzyme production in the fermentation process. Nutrients, physical conditions such as pH and temperature, and protease resistance are important factors for increasing phytase production. Fungal phytases are considered monomeric proteins and generally possess a molecular weight of between 14 and 353 kDa. Fungal phytases display a broad substrate specificity with optimal pH and temperature ranges between 1.3 and 8.0 and 37-67°C, respectively. The crystal structure of phytase has been studied in Aspergillus. Notably, thermostability engineering has been used to improve relevant enzyme properties. Furthermore, fungal phytases are widely used in food and animal feed additives to improve the efficiency of phosphorus intake and reduce the amount of phosphorus in the environment.

Lactic Fermentation as a Strategy to Improve the Nutritional and Functional Values of Pseudocereals

One of the greatest challenges is to reduce malnutrition worldwide while promoting sustainable agricultural and food systems. This is a daunting task due to the constant growth of the population and the increasing demands by consumers for functional foods with higher nutritional values. Cereal grains are the most important dietary energy source globally; wheat, rice, and maize currently provide about half of the dietary energy source of humankind. In addition, the increase of celiac patients worldwide has motivated the development of gluten-free foods using alternative flour types to wheat such as rice, corn, cassava, soybean, and pseudocereals (amaranth, quinoa, and buckwheat). Amaranth and quinoa have been cultivated since ancient times and were two of the major crops of the Pre-Colombian cultures in Latin- America. In recent years and due to their well-known high nutritional value and potential health benefits, these pseudocereals have received much attention as ideal candidates for gluten-free products. The importance of exploiting these grains for the elaboration of healthy and nutritious foods has forced food producers to develop novel adequate strategies for their processing. Fermentation is one of the most antique and economical methods of producing and preserving foods and can be easily employed for cereal processing. The nutritional and functional quality of pseudocereals can be improved by fermentation using Lactic Acid Bacteria (LAB). This review provides an overview on pseudocereal fermentation by LAB emphasizing the capacity of these bacteria to decrease antinutritional factors such as phytic acid, increase the functional value of phytochemicals such as phenolic compounds, and produce nutritional ingredients such as B-group vitamins. The numerous beneficial effects of lactic fermentation of pseudocereals can be exploited to design novel and healthier foods or grain ingredients destined to general population and especially to patients with coeliac disease.

Thermostable phytase in feed and fuel industries

Phytase with wide ranging biochemical properties has long been utilized in a multitude of industries, even so, thermostability plays a crucial factor in choosing the right phytase in a few of the sectors. Mesophilic phytases are not considered to be a viable option in the feed industry owing to its limited stability in the required feed processing temperature. In the recent past, inclusion of thermostable phytase in fuel ethanol production from starch based raw material has been demonstrated with economic benefits. Therefore, considerable emphasis has been placed on using complementary approaches such as mining of extremophilic microbial wealth, encapsulation and using enzyme engineering for obtaining stable phytase variants. This article means to give an insight on role of thermostable phytases in feed and fuel industries and methods for its development, highlighting molecular determinants of thermostability.

A novel protein tyrosine phosphatase like phytase from Lactobacillus fermentum NKN51: Cloning, characterization and application in mineral release for food technology applications

A novel protein tyrosine phosphatase like phytase (PTPLP), designated as PhyLf from probiotic bacterium Lactobacillus fermentum NKN51 was identified, cloned, expressed and characterized. The recombinant PhyLf showed specific activity of 174.5 U/mg. PhyLf exhibited strict specificity towards phytate and optimum temperature at 60 °C, pH 5.0 and ionic strength of 100 mM. K_m and K_cat of PhyLf for phytate were 0.773 mM and 84.31 s^-1, respectively. PhyLf exhibited high resistance against oxidative inactivation. PhyLf shares no homology, sans the active site with reported PTLPs, warranting classification as a new subclass. Dephytinization of durum wheat and finger millet under in vitro gastrointestinal conditions using PhyLf enhanced the bioaccessibility of mineral ions. Probiotic origin, phytate specificity, resistance to oxidative environment and gastric milieu coupled with ability to release micronutrients are unique properties of PhyLf which present a strong case for its use in ameliorating nutritional value of cereals and animal feed.