Molecular gene cloning and overexpression of the phytase from Debaryomyces castellii CBS 2923

Phytase blends for enhanced phosphorous mobilization of deoiled seeds

Phytases are hydrolytic enzymes capable of a stepwise phosphate release from phytate which is the main phosphorous storage in seeds, cereals and legumes. Limitations such as low enzyme activity or incomplete phytate hydrolysis to inositol are a great challenge in phytase applications in food and feed. Herein we report a phytase blend of two enzymes with additive effects on phytate (InsP6) hydrolysis and its application in the enzymatic phosphorous recovery process. Blending the fast 6-phytase rPhyXT52 with the 3-phytase from Debaryomyces castellii, which is capable of fully hydrolyzing InsP6, we achieved rapid phosphate release with higher yields compared to the individual enzymes and a rapid disappearance of InsP6-3 intermediates, monitored by HPLC. NMR data suggest a nearly complete phytate hydrolysis to inositol and phosphate. The blend was applied for phosphate mobilization from phytate-rich biomass, such as deoiled seeds. For this emerging application, an up to 43% increased phosphate mobilization yield was achieved when using 1000 U of the blend per kg biomass compared to using only the E. coli phytase. Even so, the time of enzyme treatment was decreased by more than half (6 h instead of 16 h) when using 4000 U of blend, we reached a 78-90% reduction of the total phosphorous content in the explored deoiled seeds. In summary, the phytase blend of Dc phyt/rPhyXT52 was proven very efficient to obtain inositol phosphate depleted meal which has its potential application in animal feeding and is concomitant with the production of green phosphate from renewable resources.

Screening For Yeast Phytase Leads to the Identification of a New Cell-Bound and Secreted Activity in Cyberlindnera jadinii CJ2

Phytic acid is an anti-nutritional compound able to chelate proteins and ions. For this reason, the food industry is looking for a convenient method which allows its degradation. Phytases are a class of enzymes that catalyze the degradation of phytic acid and are used as additives in feed-related industrial processes. Due to their industrial importance, our goal was to identify new activities that exhibit best performances in terms of tolerance to high temperature and acidic pH. As a result of an initial screening on 21 yeast species, we focused our attention on phytases found in Cyberlindnera jadinii, Kluyveromyces marxianus, and Torulaspora delbrueckeii. In particular, C. jadinii showed the highest secreted and cell-bound activity, with optimum of temperature and pH at 50°C and 4.5, respectively. These characteristics suggest that this enzyme could be successfully used for feed as well as for food-related industrial applications.

Genetic transformation of tropical maize (Zea mays L.) inbred line with a phytase gene from Aspergillus niger

A full-length cDNA of phyA gene of Aspergillus niger, encoding phytase enzyme, was cloned and expressed in E. coli BL21 cells and assayed for its activity. The phyA cDNA consisted of 1404 bp, which encoded 467 amino acid residues. The phytase activity of purified phytase was 826.33 U/mL. The phyA gene under the control of endosperm-specific promoters was transformed into an Indian maize inbred line, UMI29, using particle bombardment-mediated transformation method to generate transgenic maize plants over-expressing phytase in seeds. PCR and GUS analyses demonstrated the presence of transgenes in T₀ transgenic plants and their stable inheritance in the T₁ progenies. Three transgenic events expressing detectable level of A. niger phytase were characterized by western blot analysis. Phytase activity of 463.158 U/kg of seed was observed in one of the events, JB-UMI29-Z17/2. The phytase activity of transgenic maize seeds was 5.5- to 7-fold higher than the wild-type UMI29 seeds and, consequently, the seeds had 0.6- to 5-fold higher inorganic phosphorus content.

Optimization of the fermentation and downstream processes for human enterokinase production in Pichia pastoris

Enterokinase is one of the most frequently used enzymes for the removal of affinity tags from target recombinant proteins. In this study, several fermentation strategies were assayed for the production of human enterokinase in Pichia pastoris under constitutive GAP promoter. Two of them with controlled specific growth rate during whole cultivation showed a very low enterokinase activity, under 1 U/ml, of the fermentation medium. On the contrary, the combined fermentation with a maximum specific growth rate at the initial phase of the fermentation and stationary-like phase during the rest of the fermentation showed a significant accumulation of the enterokinase in the medium, which counted up to 1400 U/ml. Lower cultivation temperature had a negative impact on the enzyme accumulation during this fermentation strategy. Downstream processes were focused on buffer environment optimization directly after cultivation, as at this time, the most amount of the activity is eliminated by endogenous proteases. Slightly positive effect on enzyme activity in the medium had an addition of liquid storage solution of EDTA and KOH to adjust pH to 8 and molarity of the EDTA to 50 mM. During the purification process, a significant amount of the enzyme was detected to be lost, which counted up to 90%. The purified enzyme, enterokinase, kept quality standard of the published enzymes.

Bacillus phytases: Current status and future prospects

Phytases catalyze the hydrolysis of phytic acid in a stepwise manner to lower inositol phosphates, myo-inositol (having important role in metabolism and signal transduction pathways), and inorganic phosphate. These enzymes have been widely used in animal feed in order to improve phosphorus nutrition and to decrease pollution in animal waste. Compared to previously described phytases, the phytase (PhyL) from Bacillus licheniformis ATCC 14580 has attractive biochemical properties which can increase the profitability of several biotechnological procedures (animal nutrition, humain health…etc). Due to its amino acid sequence with critical substitutions, the PhyL could be a model to enhance other phytases features, in terms of thermal stability and high activity. Otherwise, an engineered PhyL, with low pH optimum, will represent a challenge within the class of β- propeller phytases.

Phytase-producing capacity of yeasts isolated from traditional African fermented food products and PHYPk gene expression of Pichia kudriavzevii strains

Phytate is known as a strong chelate of minerals causing their reduced uptake by the human intestine. Ninety-three yeast isolates from traditional African fermented food products, belonging to nine species (Pichia kudriavzevii, Saccharomyces cerevisiae, Clavispora lusitaniae, Kluyveromyces marxianus, Millerozyma farinosa, Candida glabrata, Wickerhamomyces anomalus, Hanseniaspora guilliermondii and Debaryomyces nepalensis) were screened for phytase production on solid and liquid media. 95% were able to grow in the presence of phytate as sole phosphate source, P. kudriavzevii being the best growing species. A phytase coding gene of P. kudriavzevii (PHYPk) was identified and its expression was studied during growth by RT-qPCR. The expression level of PHYPk was significantly higher in phytate-medium, compared to phosphate-medium. In phytate-medium expression was seen in the lag phase. Significant differences in gene expression were detected among the strains as well as between the media. A correlation was found between the PHYPk expression and phytase extracellular activity.

Optimization of heterologous expression of the phytase (PPHY) of Pichia anomala in P. pastoris and its applicability in fractionating allergenic glycinin from soy protein

The phytase (PPHY) of Pichia anomala has the requisite properties of thermostability and acidstability, broad substrate spectrum, and protease insensitivity, which make it a suitable candidate as a feed and food additive. The 1,389-bp PPHY gene was amplified from P. anomala genomic DNA, cloned in pPICZαA, and expressed extracellularly in P. pastoris X33. Three copies of PPHY have been detected integrated into the chromosomal DNA of the recombinant P. pastoris. The size exclusion chromatography followed by electrophoresis of the pure rPPHY confirmed that this is a homohexameric glycoprotein of ~420 kDa with a 24.3 % portion as N-linked glycans. The temperature and pH optima of rPPHY are 60 °C and 4.0, similar to the endogenous enzyme. The kinetic characteristics K(m), V(max), K(cat), and K(cat)/K(m) of rPPHY are 0.2 ± 0.03 mM, 78.2 ± 1.43 nmol mg(-1) s(-1), 65,655 ± 10.92 s(-1), and 328.3 ± 3.12 μM(-1) s(-1), respectively. The optimization of medium components led to a 21.8-fold improvement in rPPHY production over the endogenous yeast. The rPPHY titer attained in shake flasks could also be sustained in the laboratory fermenter. The rPPHY accounts for 57.1 % of the total secreted protein into the medium. The enzyme has been found useful in fractionating allergenic protein glycinin from soya protein besides dephytinization.

Production of phytase under solid-state fermentation using Rhizopus oryzae: novel strain improvement approach and studies on purification and characterization

Present study introduces linseed oil cake as a novel substrate for phytase production by Rhizopus oryzae. Statistical approach was employed to optimize various medium components under solid state fermentation (SSF). An overall 8.41-fold increase in phytase production was achieved at the optimum concentrations (w/w, mannitol, 2.05%; ammonium sulfate, 2.84% and phosphate, 0.38%). Further enhancement by 59% was observed due to a novel strain improvement approach. Purified phytase (∼34 kDa) showed optimal temperature of 45 °C, dual pH optima at 1.5 and 5.5 and possesses high catalytic efficiency (2.38×10(6) M(-1) s(-1)). Characterization study demonstrates the phytase as highly thermostable and resistant to proteolysis, heavy metal ions, etc. Furthermore, an improved HPLC method was introduced to confirm the ability of phytase to degrade phytic acid completely and was found to be an efficient method.

A Thermostable phytase from Neosartorya spinosa BCC 41923 and its expression in Pichia pastoris

A phytase gene was cloned from Neosartorya spinosa BCC 41923. The gene was 1,455 bp in size, and the mature protein contained a polypeptide of 439 amino acids. The deduced amino acid sequence contains the consensus motif (RHGXRXP) which is conserved among phytases and acid phosphatases. Five possible disulfide bonds and seven potential N-glycosylation sites have been predicted. The gene was expressed in Pichia pastoris KM71 as an extracellular enzyme. The purified enzyme had specific activity of 30.95 U/mg at 37°C and 38.62 U/mg at 42°C. Molecular weight of the deglycosylated recombinant phytase, determined by SDS-PAGE, was approximately 52 kDa. The optimum pH and temperature for activity were pH 5.5 and 50°C. The residual phytase activity remained over 80% of initial activity after the enzyme was stored in pH 3.0 to 7.0 for 1 h, and at 60% of initial activity after heating at 90°C for 20 min. The enzyme exhibited broad substrate specificity, with phytic acid as the most preferred substrate. Its K (m) and V (max) for sodium phytate were 1.39 mM and 434.78 U/mg, respectively. The enzyme was highly resistant to most metal ions tested, including Fe(2+), Fe(3+), and Al(3+). When incubated with pepsin at a pepsin/phytase ratio of 0.02 (U/U) at 37°C for 2 h, 92% of its initial activity was retained. However, the enzyme was very sensitive to trypsin, as 5% of its initial activity was recovered after treating with trypsin at a trypsin/phytase ratio of 0.01 (U/U).

Cloning and characterization of a novel phytase from wastewater treatment yeast Hansenula fabianii J640 and expression in Pichia pastoris

Phosphohydrolysis of organic phosphorus compounds by acid phosphatases (EC 3.1.3.1 and EC 3.1.3.2) is an important method for efficient removal of phosphorus from high concentration organic wastewater. Another important method is supplementation of animal feed with phytase (EC 3.1.3.8 and EC 3.1.3.26), which improves the availability of phytate-phosphates (phosphate that are hydrolyzed by phytases), making it possible to add less phosphate to animal feed and resulting in the excretion of less phosphorus by the animals. In the present study, we purified a novel phytase from the wastewater treatment yeast Hansenula fabianii J640 (Hfphytase), cloned the 1456 bp open reading frame (ORF) encoding Hfphytase, and characterized Hfphytase. The molecular weight of Hfphytase after deglycosylation by PNGaseF was 49 kDa. The optimal pH and temperature for enzyme activity were 4.5 and 50 degrees C, respectively. Hfphytase exhibits 40% identity with Debaryomyces castellii phytase, 37% identity with Aspergillus niger PhyB, and 34% identity with Saccharomyces cerevisiae Pho5p. Recombinant Hfphytase was transformed and expressed in Pichia pastoris. The yield was 23 g/l by jar fermenter cultivation. The marked phosphohydrolysis activity exhibited by Hfphytase on six substrates (pNP-P, sodium phytate, glucose-1 phosphate, glucose-6 phosphate, alpha-glycerophosphate and beta-glycerophosphate) indicated that it is a non-specific acid phosphatase.

Simultaneous degradation of phytic acid and starch by an industrial strain of Saccharomyces cerevisiae producing phytase and alpha-amylase

Phytase liberates inorganic phosphate from phytic acid (myo-inositol hexakisphosphate) which is the major phosphate reserve in plant-derived foods and feeds. An industrial strain of Saccharomyces cerevisiae expressing the Debaryomyces castellii phytase gene (phytDc) and D. occidentalis alpha-amylase gene (AMY) was developed. The phytDc and AMY genes were constitutively expressed under the ADC1 promoter in S. cerevisiae by using the delta-integration system, which contains DNA derived exclusively from yeast. The recombinant industrial strain secreted both phytase and alpha-amylase for the efficient degradation of phytic acid and starch as main components of plant seeds. This new strain hydrolyzed 90% of 0.5% (w/v) sodium phytate within 5 days of growth and utilized 100% of 2% (w/v) starch within 48 h simultaneously.

Molecular cloning, characterization, and expression of the phytase gene from marine yeast Kodamaea ohmeri BG3

The extracellular phytase structural gene was isolated from the cDNA of the marine yeast, Kodamaea ohmeri BG3, using the switching mechanism at 5'-end of RNA transcript (SMART)trade mark rapid-amplification of cDNA ends (RACE) cDNA amplification kit. The gene had an open reading frame of 1389 bp and the coding region of the gene had no intron. It encoded 462 amino acid residues of a protein with a putative signal peptide of 15 amino acids. The protein sequence deduced from the extracellular phytase structural gene contained the consensus motifs (RHGXRX P and HD), which are conserved among histidine acid phosphatases, and six conserved putative N-glycosylation sites. According to the phylogenetic tree of the phytase, the phytase from K. ohmeri BG3 was closely related to Candida albicans (XP_713452) and Pichia stipitis (XP_001385108) phytase proteins and more distantly related to other phytases. The mature peptide encoding cDNA was subcloned into the pET-24a (+) expression vector. The recombinant plasmid [pET-24a (+)PHY1] was expressed in Escherichia coli BL21 (DE3). The expressed fusion protein was analysed by SDS-PAGE and Western blotting, and a specific band with a molecular mass of about 51 kDa was found. An enzyme activity assay verified the recombinant protein as a phytase. A maximum activity of 16.5 U mg(-1) was obtained from the cellular extract of E. coli BL21 (DE3) harbouring pET-24a (+)PHY1. The optimal pH and temperature of the crude recombinant lipase were 5 and 65 degrees C, respectively, and the crude recombinant phytase had hydrolytic activity towards phytate.