Transgenic soybean expressing a thermostable phytase as substitution for feed additive phytase

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.

Advances in Soybean Genetic Improvement

The soybean (Glycine max) is a globally important crop due to its high protein and oil content, which serves as a key resource for human and animal nutrition, as well as bioenergy production. This review assesses recent advancements in soybean genetic improvement by conducting an extensive literature analysis focusing on enhancing resistance to biotic and abiotic stresses, improving nutritional profiles, and optimizing yield. We also describe the progress in breeding techniques, including traditional approaches, marker-assisted selection, and biotechnological innovations such as genetic engineering and genome editing. The development of transgenic soybean cultivars through Agrobacterium-mediated transformation and biolistic methods aims to introduce traits such as herbicide resistance, pest tolerance, and improved oil composition. However, challenges remain, particularly with respect to genotype recalcitrance to transformation, plant regeneration, and regulatory hurdles. In addition, we examined how wild soybean germplasm and polyploidy contribute to expanding genetic diversity as well as the influence of epigenetic processes and microbiome on stress tolerance. These genetic innovations are crucial for addressing the increasing global demand for soybeans, while mitigating the effects of climate change and environmental stressors. The integration of molecular breeding strategies with sustainable agricultural practices offers a pathway for developing more resilient and productive soybean varieties, thereby contributing to global food security and agricultural sustainability.

Insight into phytase-producing microorganisms for phytate solubilization and soil sustainability

The increasing demand for food has increased dependence on chemical fertilizers that promote rapid growth and yield as well as produce toxicity and negatively affect nutritional value. Therefore, researchers are focusing on alternatives that are safe for consumption, non-toxic, cost-effective production process, and high yielding, and that require readily available substrates for mass production. The potential industrial applications of microbial enzymes have grown significantly and are still rising in the 21st century to fulfill the needs of a population that is expanding quickly and to deal with the depletion of natural resources. Due to the high demand for such enzymes, phytases have undergone extensive research to lower the amount of phytate in human food and animal feed. They constitute efficient enzymatic groups that can solubilize phytate and thus provide plants with an enriched environment. Phytases can be extracted from a variety of sources such as plants, animals, and microorganisms. Compared to plant and animal-based phytases, microbial phytases have been identified as competent, stable, and promising bioinoculants. Many reports suggest that microbial phytase can undergo mass production procedures with the use of readily available substrates. Phytases neither involve the use of any toxic chemicals during the extraction nor release any such chemicals; thus, they qualify as bioinoculants and support soil sustainability. In addition, phytase genes are now inserted into new plants/crops to enhance transgenic plants reducing the need for supplemental inorganic phosphates and phosphate accumulation in the environment. The current review covers the significance of phytase in the agriculture system, emphasizing its source, action mechanism, and vast applications.

Progress in Soybean Genetic Transformation Over the Last Decade

Soybean is one of the important food, feed, and biofuel crops in the world. Soybean genome modification by genetic transformation has been carried out for trait improvement for more than 4 decades. However, compared to other major crops such as rice, soybean is still recalcitrant to genetic transformation, and transgenic soybean production has been hampered by limitations such as low transformation efficiency and genotype specificity, and prolonged and tedious protocols. The primary goal in soybean transformation over the last decade is to achieve high efficiency and genotype flexibility. Soybean transformation has been improved by modifying tissue culture conditions such as selection of explant types, adjustment of culture medium components and choice of selection reagents, as well as better understanding the transformation mechanisms of specific approaches such as Agrobacterium infection. Transgenesis-based breeding of soybean varieties with new traits is now possible by development of improved protocols. In this review, we summarize the developments in soybean genetic transformation to date, especially focusing on the progress made using Agrobacterium-mediated methods and biolistic methods over the past decade. We also discuss current challenges and future directions.

Safety assessment of phytase transgenic maize 11TPY050 in Sprague-Dawley rats by 90-day feeding study

The present study aimed to evaluate the subchronic toxicity of feeding with phytase-transgenic maize line 11TPY050 in Sprague-Dawley (SD) rats. Rats (n = 10/sex/group) were fed with 12.5%, 25% or 50% (w/w) transgenic maize diet, 12.5%, 25% or 50% (w/w) non-transgenic isoline OSL940 maize diet, or 50% (w/w) commercially available Zhengdan958 maize diet for 90 days. Daily clinical observations and weekly measurements of body weights and food consumption were conducted. Blood samples were collected on day 46 and day 91 for hematology and clinical chemistry evaluations. At the end of the study, macroscopic and microscopic examinations were performed. No effects on body weight and food consumption were observed. The results of hematology, clinical chemistry, and absolute and relative organ weights in the transgenic maize group were comparable to those in the parental maize group. Several statistical differences were not dose-related and were not considered to be biologically significant. Furthermore, the terminal necropsy and histopathological examination showed no treatment-related changes among the groups. The results from the present 90-day feeding study of phytase-transgenic maize 11TPY050 indicated no unexpected adverse effects in SD rats. The phytase transgenic maize 11TPY050 has substantial equivalence with non-transgenic maize.

Snapshots during the catalytic cycle of a histidine acid phytase reveal an induced-fit structural mechanism

Highly engineered phytases, which sequentially hydrolyze the hexakisphosphate ester of inositol known as phytic acid, are routinely added to the feeds of monogastric animals to improve phosphate bioavailability. New phytases are sought as starting points to further optimize the rate and extent of dephosphorylation of phytate in the animal digestive tract. Multiple inositol polyphosphate phosphatases (MINPPs) are clade 2 histidine phosphatases (HP2P) able to carry out the stepwise hydrolysis of phytate. MINPPs are not restricted by a strong positional specificity making them attractive targets for development as feed enzymes. Here, we describe the characterization of a MINPP from the Gram-positive bacterium Bifidobacterium longum (BlMINPP). BlMINPP has a typical HP2P-fold but, unusually, possesses a large α-domain polypeptide insertion relative to other MINPPs. This insertion, termed the U-loop, spans the active site and contributes to substrate specificity pockets underpopulated in other HP2Ps. Mutagenesis of U-loop residues reveals its contribution to enzyme kinetics and thermostability. Moreover, four crystal structures of the protein along the catalytic cycle capture, for the first time in an HP2P, a large ligand-driven α-domain motion essential to allow substrate access to the active site. This motion recruits residues both downstream of a molecular hinge and on the U-loop to participate in specificity subsites, and mutagenesis identified a mobile lysine residue as a key determinant of positional specificity of the enzyme. Taken together, these data provide important new insights to the factors determining stability, substrate recognition, and the structural mechanism of hydrolysis in this industrially important group of enzymes.

Probiotic properties of a phytase producing Pediococcus acidilactici strain SMVDUDB2 isolated from traditional fermented cheese product, Kalarei

The nutritional challenge faced by the monogastric animals due to the chelation effects of phytic acid, fuel the research on bioprospecting of probiotics for phytase production. Pediococcus acidilactici SMVDUDB2 isolated from Kalarei, exhibited extracellular phytase activity of 5.583 U/mL after statistical optimization of fermentation conditions viz. peptone (1.27%); temperature (37 °C); pH (6.26) and maltose (1.43%). The phytase enzyme possessed optimum pH and temperature of 5.5 and 37 °C, respectively and was thermostable at 60 °C. The enzyme was purified 6.42 fold with a specific activity of 245.12 U/mg with hydrophobic interaction chromatography. The purified enzyme had K_m and V_max values of 0.385 mM and 4.965 μmol/min respectively, with sodium phytate as substrate. The strain depicted more than 80% survival rate at low pH (pH 2.0, 3.0), high bile salt concentration (0.3 and 0.5%), after gastrointestinal transit, highest hydrophobicity affinity with ethyl acetate (33.33 ± 0%), autoaggregation (77.68 ± 0.68%) as well as coaggregation (73.57 ± 0.47%) with Staphylococcus aureus (MTCC 3160). The strain exhibited antimicrobial activity against Bacillus subtilis (MTCC 121), Mycobacterium smegmatis (MTCC 994), Staphylococcus aureus (MTCC 3160), Proteus vulgaris (MTCC 426), Escherichia coli (MTCC 1652) and Lactobacillus rhamnosus (MTCC 1408). The amount of exopolysaccharide produced by the strain was 2 g/L. This strain having the capability of phytate degradation and possessing probiotic traits could find application in food and feed sectors.