A bioprocess for the production of phytase from Schizophyllum commune: studies of its optimization, profile of fermentation parameters, characterization and stability

Review on Desirable Microbial Phytases as a Poultry Feed Additive: Their Sources, Production, Enzymatic Evaluation, Market Size, and Regulation

Poultry's digestive tract lacks hydrolytic phytase enzymes, which results in chelation of dietary minerals, vital amino acids, proteins, and carbohydrates, phytate-phosphate unavailability, and contamination of the environment due to phosphorus. Therefore, it is necessary to use exogenous microbial phytases as feed additive to chicken feed to catalyze the hydrolysis of dietary phytate. Potential sources of microbial isolates that produce desired phytases for chicken feed supplementation have been isolated from agricultural croplands. It is achievable to isolate phytase-producing bacteria isolates using both broth and agar phytase screening media. Potential substrates for submerged fermentation (SmF) for bacterial phytase production and solid-state fermentation (SSF) for fungal phytase production include rice and wheat bran. Following fermentation, saturated ammonium sulphate precipitation is typically used to partially purify microbial culture filtrate. The precipitate is then desalted. Measurements of the pH optimum and stability, temperature optimum and stability, metal ions stability, specificity and affinity to target substrate, proteolysis resistance, storage stability, and in vitro feed dephosphorylation are used to perform an enzymatic evaluation of phytase as an additive for poultry feed. The growth of the feed phytase market is primarily due to the expansion of chicken farms to meet the demand for meat and eggs from humans. The Food and Drug Administration in the USA and the European Food and Safety Authority are primarily in charge of putting rules pertaining to feed phytase use in chicken feed into effect. Conclusively, important components of the production of phytase additives for poultry feed include identifying a reliable source for potential microbe isolation, selecting an economical method of phytase production, thoroughly characterizing the biochemical properties of phytase, and comprehending the size and regulation of the current feed phytase market.

Bioinformatic Studies, Experimental Validation of Phytase Production and Optimization of Fermentation Conditions for Enhancing Phytase Enzyme Production by Different Microorganisms under Solid-State Fermentation

Background:

Phytase is an essential enzyme necessary for the digestive process. It is a natural enzyme found in plant materials. It prevents bad effect of phytic acid on protein and energy utilization. Phytase frees the bound minerals such as phosphorus, calcium, zinc, iron, magnesium and manganese from the phytic acid molecule providing essential minerals available for healthy nutrition. This study depends on converting food processing waste into highly valuable products. Optimizing the fermentation conditions for enhancing high phytase production with low cost was the objective of this research.

Methods:

A bibliographical survey was carried out to select the most fungul producers of phytase from fungal species deposited in NCBI database. Phytases of the selected organisms were analyzed in the UNIPROT database and their protein sequences were submitted to multiple sequence alignments using Clustal Omega and visualized using Jalview program. Experimental studies using five fungal strains of Aspergillus.ssp on wheat bran under Solid-State Fermentation carried out. Comparisons were made for phytase production. A. awamori NRC- F18 as the best phytase producer-strain cultured on different types of treated wastes followed by optimizing the fermentation conditions for enhancing phytase production using rice straw as the best substrate, which provides the highest phytase production. Thermostability of crude enzyme was studied. Statistical analyses were performed using SPSS at P < 0.05 or P < 0.01.

Results:

Bioinformatic studies predicted the most producer species and explained the difference in activity of phytases produced from different species, although they have the same function. All phytases of the selected fungal species from the database NCBI have highly conserved amino acid sequences; there are 88 identical positions; 135 similar positions, but the identity percentage was 16.858%. Experimental studies using five fungal strains of Aspergillus ssp. on wheat bran revealed optimum conditions for phytase production by A. awamori NRC- F18, which cultured on different types of treated wastes. A considerably higher phytase production was obtained using rice straw as substrate 424.66± 2.92 IU /g at pH 6 (371.883± 0.822 IU /g), after 144 hrs of incubation at 30°C. The maximum enzyme activity observed when solid: moisture was 1:4; Inoculum concentration 2mg/5g (418.363± 16.709 IU /g) and substrate concentration 4.5% (277.39± 12.05 IU /g). Glucose and Ammonium acetate were the best carbon and nitrogen sources that enhanced phytase production from A. awamori NRC- F18. The obtained phytase was found to be thermostable and the maximum temperature at which phytase still active was 80°C.

Conclusion:

Bioinformatic studies predicted the most producer species. Experimental study revealed that A.awamori NRC- F18 was the best Phytase -producer strain. Solid state fermentation was a good method; pretreatment of agriculture residues as rice straw was useful for less expensive phytase production, which was thermostable. A. awamori NRC- F18 can be used in the industrial production of phytase.

Production and characterization of a novel, thermotolerant fungal phytase from agro-industrial byproducts for cattle feed

OBJECTIVE

The application of phytases helps in releasing bound phosphorus and other nutrients in cattle feed eventually reducing the need for supplementations. However, high production cost owing to the unavailability of cheaper sources of phytases has limited their usage in developing countries. Herein, firstly isolation, identification of a phytase from fungal isolate, Aspergillus niger NT7 was carried out followed by optimizing of all production parameters, through solid-state fermentation (SSF). Secondly, crude phytase was characterized and potential applicability of crude phytase was evaluated for dephytinization of wheat bran.

RESULTS

The highest phytase production (208.30 ± 0.22 U/gds) was achieved using wheat bran as cheap agro-industrial substrate for SSF. The various physiological parameters were optimized including inoculum age and level (3-day old inoculum and 15 × 10⁷ spores/ml), temperature (35 °C), a moistening agent (distilled water), medium pH (5), and supplementation of various biochemicals like sugar (Mannitol), nitrogen (ammonium sulphate) and detergent (Tween 80). Process optimization through one variable at a time (OVAT) approach increased the difference in productivity to more than 200%. The crude phytase of A. niger NT7 was thermostable, with optimal activity at 60 °C and also displayed optimal activity over a broad range of acidic pH. Further, enhancement in phytase activity was found specifically in the presence of Ca²⁺, Zn²⁺, and Co²⁺ ions, while other metal ions including Fe²⁺, Fe³⁺, Mn²⁺, Mg²⁺and Cu²⁺ inhibited its activity. Finally, the phytase showed efficient and sustained release of inorganic phosphate, proteins, and reducing sugars (> 60 h) from livestock feed.

CONCLUSION

Overall, our report highlights the production of an efficient and thermotolerant phytase with potential as a low-cost animal feed supplement.

Bioprocessing of Agricultural Residues as Substrates and Optimal Conditions for Phytase Production of Chestnut Mushroom, Pholiota adiposa, in Solid State Fermentation

Phytase is an enzyme that breaks down phytates to release phosphorus in an available form. This enzyme plays an important role in animals, especially monogastric animals. It serves to improve phytate digestion along with phosphorus absorption, which are required for optimal growth performance and health. In this study, five mushroom species (Amauroderma rugosum SDBR-CMU-A83, Ganoderma mastoporum SDBR-CMU-NK0244, Marusmius sp.1 SDBR-CMU-NK0215, Pholiota adiposa SDBR-CMU-R32 and Piptoporellus triqueter SDBR-CMU-P234) out of 27 mushroom species displayed positive phytase production by agar plate assay. Consequently, these five mushroom species were selected for determination of their potential ability to produce phytase under solid-state fermentation using five agricultural residues (coffee parchment, oil palm empty fruit bunches, rice bran, sawdust, and water hyacinth) as substrates. The highest yield of phytase production (17.02 ± 0.92 units/gram dry substrate) was obtained after one week of fermentation. Optimization for phytase production was determined by statistical approaches using a Plackett-Burman design to screen ten parameters of relevant substrate components. Two significant parameters, the amount of water hyacinth and the moisture content, were found to affect the production process of phytase. Furthermore, the optimal temperature, pH value, and fermentation period were evaluated. The results indicated that the highest degree of phytase production at 53.66 ± 1.68 units/gram dry substrate (3.15-fold increase) was obtained in water hyacinth containing 85% moisture content by addition with a suitable basal liquid medium at a pH value of 6.5 after being incubated at 30 °C for seven days. The crude phytase of P. adiposa was precipitated and the precipitated extract was then used to determine partial characterizations. The precipitated extract displayed high activities after exposure to conditions of 42 °C and pH 5.0. Furthermore, Fe²⁺ enhanced phytase activity and precipitated extract displayed the best stability at a pH value of 8.0 and a temperature of 4 °C.

A biorefinery approach for the production of ferulic acid from agroresidues through ferulic acid esterase of lactic acid bacteria

Ferulic acid is a known precursor for vanillin production but the significance of agro waste as substrates for its extraction, in combination with microbes is a less explored option. Various lactic acid bacteria were screened for the production of ferulic acid esterase (FAE) and Enterococcus lactis SR1 was found to produce maximum FAE (7.54 ± 0.15 IU/ml) in the synthetic medium under submerged fermentation. To make the process cost effective, various lignocellulosic agroresidues were evaluated for the production of FAE from the bacterium. It was found that wheat bran serves as the best substrate for FAE production (4.18 ± 0.12 IU/ml) from E. lactis SR1. Further, optimization of fermentation conditions for FAE production from E. lactis SR1 using wheat bran as carbon source led to an increase in the enzyme production (7.09 ± 0.21 IU/ml) by 1.5 fold. The FAE produced was used alone or in combination with commercial holocellulase for biological release of FA from the tested agroresidues. The highest release of FA (mg/g) by enzymatic extraction occurred in sugarbeet pulp (2.56), followed by maize bran (1.45), wheat bran (1.39) and rice bran (0.87), when both the enzymes (FAE and holocellulase) were used together. Alkaline extraction and purification of ferulic acid (FA) from these agro residues also showed that sugarbeet pulp contains the highest amount of FA (5.5 mg/g) followed by maize bran (3.0 mg/g), wheat bran (2.8 mg/g) and rice bran (1.9 mg/g), similar to the trend obtained in biological/enzymatic extraction of FA from these residues. Furthermore, the substrates were found to release higher reducing sugars when both commercial holocellulase and FAE were used in combination than by the use of holocellulase alone. Thus, FAEs not only release FA but also enabled hemicellulase and cellulase to release more sugars from plant material.

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.

A Sight to Wheat Bran: High Value-Added Products

Recently more consideration has been given to the use of renewable materials and agricultural residues. Wheat production is increasing yearly and correspondingly, the volume of by-products from the wheat process is increasing, as well. It is important to find the use of the residuals for higher value-added products, and not just for the food industry or animal feed purposes as it is happening now. Agricultural residue of the roller milled wheat grain is a wheat bran description. The low-cost of wheat bran and its composition assortment provides a good source of substrate for various enzymes and organic acids production and other biotechnological applications. The main purpose of this review article is to look into recent trends, developments, and applications of wheat bran.

Production of Fungal Phytases from Agroindustrial Byproducts for Pig Diets

The application of phytases for animal feed in developing countries is limited due to the high cost of these enzymes, determined by the importation fees and the expensive substrates used for their production. In this work, we have used agroindustrial byproducts for the production of extracts containing phytases, which were accessed for their stability focusing on the conditions found in the gastrointestinal tract of pigs. The fungus Acremonim zeae presented higher phytase production in medium containing cornmeal, while the yeast Kluyveromyces marxianus produced 10-fold more phytase when cultivated on rice bran. Process optimization increased the difference in productivity to more than 300 fold. The phytase from A. zeae was thermostable, with higher activity at neutral pH and 50 °C, but was inhibited at pH 2.5 and by various ions. The phytase activity in the K. marxianus extract was stable at a wide range of conditions, which indicates the presence of at least two enzymes. As far as we know, this manuscript describes for the first time the phytase production and the characteristics of the extracts produced by both these microbial species. These enzymes could be produced at low cost and have potential to replace enzymes currently imported for this purpose.

Schizophyllum commune: An unexploited source for lignocellulose degrading enzymes

Lignocellulose represents the most abundant source of carbon in the Earth. Thus, fraction technology of the biomass turns up as an emerging technology for the development of biorefineries. Saccharification and fermentation processes require the formulation of enzymatic cocktails or the development of microorganisms (naturally or genetically modified) with the appropriate toolbox to produce a cost‐effective fermentation technology. Therefore, the search for microorganisms capable of developing effective cellulose hydrolysis represents one of the main challenges in this era. Schizophyllum commune is an edible agarical with a great capability to secrete a myriad of hydrolytic enzymes such as xylanases and endoglucanases that are expressed in a high range of substrates. In addition, a large number of protein‐coding genes for glycoside hydrolases, oxidoreductases like laccases (Lacs; EC 1.10.3.2), as well as some sequences encoding for lytic polysaccharide monooxygenases (LPMOs) and expansins‐like proteins demonstrate the potential of this fungus to be applied in different biotechnological process. In this review, we focus on the enzymatic toolbox of S. commune at the genetic, transcriptomic, and proteomic level, as well as the requirements to be employed for fermentable sugars production in biorefineries. At the end the trend of its use in patent registration is also reviewed.

Purification and characterization of a protease-resistant phytase of Aspergillus oryzae SBS50 whose properties make it exceptionally useful as a feed supplement

An extracellular phytase of Aspergillus oryzae SBS50 was purified to homogeneity using ammonium sulphate precipitation, ion-exchange and gel filtration chromatography. Purified phytase has a monomeric molecular mass of ∼80kDa exhibiting its optimal activity at pH 5.0 and 50°C with a T _1/2 of 300min at 50°C. Phytase of A. oryzae displayed broad substrate specificity with V_max and K_m values of 58.82μmol/ml/min and 1.14mM, respectively, for calcium phytate. Purity and homogeneity of the phytase was confirmed by high performance liquid chromatography and MALDI-TOF analysis revealed the identification of a peptide showing homology with acid phosphatase of Aspergillus oryzae RIB40. Among the inhibitors, 2,3-butanedione and sodium molybdate significantly inhibited the enzyme activity. Phytase of A. oryzae showed protease-resistance and was more stable during storage at 4°C and -20°C as compared to room temperature. Among all the feed samples, mustard oil cake was dephytinized more efficiently than other feed samples. These unique properties suggested that the phytase has the potential to be useful as an animal feed supplement.

Phytase production by solid-state fermentation of groundnut oil cake by Aspergillus niger: A bioprocess optimization study for animal feedstock applications

This investigation deals with the use of agro-industrial waste, namely groundnut oil cake (GOC), for phytase production by the fungi Aspergillus niger NCIM 563. Plackett-Burman design (PBD) was used to evaluate the effect of 11 process variables and studies here showed that phytase production was significantly influenced by glucose, dextrin, distilled water, and MgSO4 · 7H2O. The use of response surface methodology (RSM) by Box-Behnken design (BBD) of experiments further enhanced the production by a remarkable 36.67-fold from the original finding of 15 IU/gds (grams of dry substrate) to 550 IU/gds. This is the highest solid-state fermentation (SSF) phytase production reported when compared to other microorganisms and in fact betters the best known by a factor of 2. Experiments carried out using dried fermented koji for phosphorus and mineral release and also thermal stability have shown the phytase to be as efficient as the liquid enzyme extract. Also, the enzyme, while exhibiting optimal activity under acidic conditions, was found to have significant activity in a broad range of pH values (1.5-6.5). The studies suggest the suitability of the koji supplemented with phytase produced in an SSF process by the "generally regarded as safe" (GRAS) microorganism A. niger as a cost-effective value-added livestock feed when compared to that obtained by submerged fermentation (SmF).

A novel phytase characterized by thermostability and high pH tolerance from rice phyllosphere isolated Bacillus subtilis B.S.46

In this study, an extracellular alkali-thermostable phytase producing bacteria, Bacillus subtilis B.S.46, were isolated and molecularly identified using 16S rRNA sequencing. Response surface methodology was applied to study the interaction effects of assay conditions to obtain optimum value for maximizing phytase activity. The optimization resulted in 137% (4.627 U/mL) increase in phytase activity under optimum condition (56.5 °C, pH 7.30 and 2.05 mM sodium phytate). The enzyme also showed 60-73% of maximum activity at wide ranges of temperature (47-68 °C), pH (6.3-8.0) and phytate concentration (1.40-2.50 mM). The partially purified phytase demonstrated high stability over a wide range of pH (6.0-10.0) after 24 h, retaining 85% of its initial activity at pH 6 and even interestingly, the phytase activity enhanced at pH 8.0-10.0. It also exhibited thermostability, retaining about 60% of its original activity after 2 h at 60 °C. Cations such as Ca(2+) and Li(+) enhanced the phytase activity by 10-46% at 1 mM concentration. The phytase activity was completely inhibited by Cu(2+), Mg(2+), Fe(2+), Zn(2+), Hg(2+) and Mn(2+) and the inhibition was in a dose dependent manner. B. subtilis B.S.46 phytase had interesting characteristics to be considered as animal feed additive, dephytinization of food ingredients, and bioremediation of phosphorous pollution in the environment.

Phytase production by Aspergillus oryzae in solid-state fermentation and its applicability in dephytinization of wheat bran [corrected]

Aspergillus oryzae SBS50 secreted a high titre of phytase in solid-state fermentation (SSF) using wheat bran at 30 °C after 96 h at the initial substrate to moisture ratio of 1:2 and a water activity of 0.95. The production of phytase increased when wheat bran was supplemented with sucrose and beef extract. Further enhancement in enzyme production was recorded when the substrate was supplemented with the surfactant Triton X-100 (145 U/g of DMB). An overall 29-fold improvement in phytase production was achieved owing to optimization. Under optimized conditions, the mould secreted 9.3-fold higher phytase in SSF as compared to submerged fermentation (SmF). The mesophilic mould also secreted amylase, cellulase (CMCase), pectinase and xylanase along with phytase in SSF. Scanning electron microscopy revealed luxuriant growth of A. oryzae on wheat bran with abundant spores. The enzyme dephytinized wheat bran with concomitant liberation of inorganic phosphate.