Strain improvement and up scaling of phytase production by Aspergillus niger NCIM 563 under submerged fermentation conditions

Komagataella phaffii as a Platform for Heterologous Expression of Enzymes Used for Industry

In the 1980s, Escherichia coli was the preferred host for heterologous protein expression owing to its capacity for rapid growth in complex media; well-studied genetics; rapid and direct transformation with foreign DNA; and easily scalable fermentation. Despite the relative ease of use of E. coli for achieving the high expression of many recombinant proteins, for some proteins, e.g., membrane proteins or proteins of eukaryotic origin, this approach can be rather ineffective. Another microorganism long-used and popular as an expression system is baker's yeast, Saccharomyces cerevisiae. In spite of a number of obvious advantages of these yeasts as host cells, there are some limitations on their use as expression systems, for example, inefficient secretion, misfolding, hyperglycosylation, and aberrant proteolytic processing of proteins. Over the past decade, nontraditional yeast species have been adapted to the role of alternative hosts for the production of recombinant proteins, e.g., Komagataella phaffii, Yarrowia lipolytica, and Schizosaccharomyces pombe. These yeast species' several physiological characteristics (that are different from those of S. cerevisiae), such as faster growth on cheap carbon sources and higher secretion capacity, make them practical alternative hosts for biotechnological purposes. Currently, the K. phaffii-based expression system is one of the most popular for the production of heterologous proteins. Along with the low secretion of endogenous proteins, K. phaffii efficiently produces and secretes heterologous proteins in high yields, thereby reducing the cost of purifying the latter. This review will discuss practical approaches and technological solutions for the efficient expression of recombinant proteins in K. phaffii, mainly based on the example of enzymes used for the feed industry.

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.

Phytase production by Aspergillus niger NCIM 563 for a novel application to degrade organophosphorus pesticides

The production of phytase using Aspergillus niger NCIM 563 under submerged fermentation conditions was studied using protein rich chickpea flour as substrate. Employing a hybrid statistical media optimization strategy of Plackett-Burman and Box-Behnken experimental designs in shake-flasks gave an increased phytase activity from an initial 66 IU/mL in 216 h to 160 IU/mL in a reduced time of 132 h. Productivity, thus increased by 3.97 times from 7.3 to 29 IU/mL/day. Using the optimized media, the production was successfully scaled-up further and improved up to 164 IU/mL in 96 h by studies carried out employing 2 and 10-L fermenters. The enzyme supernatant was recovered using centrifugal separation of biomass and the stability of the produced phytase was tested for animal feed applications under gastric conditions. In vitro degradation studies of water soluble monocrotophos, methyl parathion and water insoluble chlorpyrifos, pesticides used extensively in agriculture was carried out. It was observed by HPLC analysis that phytase could degrade 72% of chlorpyrifos at pH 7.0, 35 °C. Comparable results were obtained with monocrotophos and methyl parathion. With chlorpyrifos at higher temperature 50 °C as much as 91% degradation could be obtained. The degradation of chlorpyrifos was further validated by spraying phytase on harvested green chilli (Capsicum annuum L) under normal conditions of pH 7.0, 35 °C and the degradation products obtained analyzed by LCMS. Thus, the present study brings out a potentially novel application of phytase for biodegradation of organophosphorus pesticides.

Enhanced Aspergillus ficuum phytase production in fed-batch and continuous fermentations in the presence of talcum microparticles

This study aimed to enhance Aspergillus ficuum phytase production in fed-batch and continuous fermentations with addition of talcum microparticles. Phytase activity almost doubled in fed-batch and continuous fermentations by addition of 15 g/l of talcum compared to the control. Effect of talcum on fungal morphology was also shown that addition of talcum provided smaller fungal pellets and more homogenized fermentation broth compared to the control. Average fungal pellet radius decreased from 500 to 100 µm by addition of 15 g/l of talcum in the bioreactors. Also, 15 g/l talcum addition increased phytase productivity and optimum dilution rate in the continuous fermentations from 0.293 to 0.621 U/ml/h and from 0.09 to 0.1/h, respectively, compared to control.

Microparticle-enhanced Aspergillus ficuum phytase production and evaluation of fungal morphology in submerged fermentation

Phytase can be used in animal's diets to increase the absorption of several divalent ions, amino acids and proteins and to decrease the excessive phosphorus release in manure to prevent negative effects on the environment. This study aimed to enhance the current submerged fungal phytase productions with a novel fermentation technique by evaluating the effect of the various microparticles on Aspergillus ficuum phytase production. It was observed that microparticles prevented bulk fungal pellet growth, decreased average fungal pellet size and significantly increased phytase activity in the submerged fermentation. Microbial structure imaging results showed that the average fungal pellet radius decreased from 800 to 500 and 200 µm by addition of 15 g/L aluminum oxide and talcum, respectively, in shake-flask fermentation. Also, addition of 15 g/L of talcum and aluminum oxide increased phytase activity to 2.01 and 2.93 U/ml, respectively, compared to control (1.02 U/ml) in shake-flask fermentation. Additionally, phytase activity reached 6.49 U/ml within 96 h of fermentation with the addition of 15 g/L of talcum, whereas the maximum phytase activity was only 3.45 U/ml at 120 h of fermentation for the control in the 1-L working volume bioreactors. In conclusion, microparticles significantly increased fungal phytase activity and production yield compared to control fermentation.

Purification and characterization of a novel neutral and heat-tolerant phytase from a newly isolated strain Bacillus nealsonii ZJ0702

Background

Phytic acid and phytates can interact with biomolecules, such as proteins and carbohydrates, and are anti-nutritional factors found in food and feed. Therefore, it is necessary to remove these compounds in food and feed processing. Phytase can hydrolyze phytic acid and phytates to release a series of lower phosphate esters of myoinositol and orthophosphate. Thus, the purification and characterization of novel phytases that can be used in food and feed processing is of particular interest to the food and feed industries.

Results

A novel neutral and heat-tolerant phytase from a newly isolated strain Bacillus nealsonii ZJ0702 was purified to homogeneity with a yield of 5.7% and a purification fold of 44. The molecular weight of the purified phytase obtained by SDS-PAGE was 43 kDa. The homology analysis based on N-terminal amino acid and DNA sequencing indicated that the purified phytase was different from other known phytases. The optimal thermal and pH activity of the phytase was observed at 55°C and 7.5, respectively. Seventy-three percent of the original activity of the phytase was maintained following incubation at 90°C for 10 min. The phytase was stable within a pH range of 6.0 − 8.0 and showed high substrate specificity for sodium phytate. Cu²⁺, Co²⁺, Zn²⁺, Mn²⁺, Ba²⁺ and Ni²⁺ ions were found to inhibit the activity of the phytase.

Conclusions

A novel phytase purified from B. nealsonii ZJ0702 was identified. The phytase was found to be thermally stable over a wide temperature range at neutral pH. These properties suggest that this phytase is a suitable alternative to fungal phytases for the hydrolysis of phytic acid and phytates in food and feed processing industries.

Improved production of protease-resistant phytase by Aspergillus oryzae and its applicability in the hydrolysis of insoluble phytates

Among three hundred isolates of filamentous fungi, Aspergillus oryzae SBS50 secreted higher phytase activity at pH 5.0, 35 °C and 200 rpm after 96 h of fermentation. Starch and beef extract supported the highest phytase production than other carbon and nitrogen sources. A nine-fold improvement in phytase production was achieved due to optimization. Supplementation of the medium with inorganic phosphate repressed the enzyme synthesis. Among surfactants tested, Tween 80 increased fungal growth and phytase production, which further resulted in 5.4-fold enhancement in phytase production. The phytase activity was not much affected by proteases treatment. The enzyme resulted in the efficient hydrolysis of insoluble phytate complexes (metal- and protein–phytates) in a time dependent manner. Furthermore, the hydrolysis of insoluble phytates was also supported by scanning electron microscopy. The enzyme, being resistant to trypsin and pepsin, and able to hydrolyze insoluble phytates, can find an application in the animal food/feed industry for improving nutritional quality and also in combating environmental phosphorus pollution and plant growth promotion.

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.

Purification and characterization of two distinct acidic phytases with broad pH stability from Aspergillus niger NCIM 563

Aspergillus niger NCIM 563 produced two different extracellular phytases (Phy I and Phy II) under submerged fermentation conditions at 30°C in medium containing dextrin-glucose-sodium nitrate-salts. Both the enzymes were purified to homogeneity using Rotavapor concentration, Phenyl-Sepharose column chromatography and Sephacryl S-200 gel filtration. The molecular mass of Phy I and II as determined by SDS-PAGE and gel filtration were 66, 264, 150 and 148 kDa respectively, indicating that Phy I consists of four identical subunits and Phy II is a monomer. The pI values of Phy I and II were 3.55 and 3.91, respectively. Phy I was highly acidic with optimum pH of 2.5 and was stable over a broad pH range (1.5-9.0) while Phy II showed a pH optimum of 5.0 with stability in the range of pH 3.5-9.0. Phy I exhibited very broad substrate specificity while Phy II was more specific for sodium phytate. Similarly Phy II was strongly inhibited by Ag(+), Hg(2+) (1 mM) metal ions and Phy I was partially inhibited. Peptide analysis by Mass Spectrometry (MS) MALDI-TOF also indicated that both the proteins were totally different. The K(m) for Phy I and II for sodium phytate was 2.01 and 0.145 mM while V(max) was 5,018 and 1,671 μmol min(-1) mg(-1), respectively. The N-terminal amino acid sequences of Phy I and Phy II were FSYGAAIPQQ and GVDERFPYTG, respectively. Phy II showed no homology with Phy I and any other known phytases from the literature suggesting its unique nature. This, according to us, is the first report of two distinct novel phytases from Aspergillus niger.