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

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.

The occurrence, role, and management strategies for phytic acid in foods

Phytic acid, a naturally occurring compound predominantly found in cereals and legumes, is the focus of this review. This review investigates its distribution across various food sources, elucidating its dual roles in foods. It also provides new insights into the change in phytic acid level during food storage and the evolving trends in phytic acid management. Although phytic acid can function as a potent color stabilizer, flavor enhancer, and preservative, its antinutritional effects in foods restrict its applications. In terms of management strategies, numerous treatments for degrading phytic acid have been reported, each with varying degradation efficacies and distinct mechanisms of action. These treatments encompass traditional methods, biological approaches, and emerging technologies. Traditional processing techniques such as soaking, milling, dehulling, heating, and germination appear to effectively reduce phytic acid levels in processed foods. Additionally, fermentation and phytase hydrolysis demonstrated significant potential for managing phytic acid in food processing. In the future, genetic modification, due to its high efficiency and minimal environmental impact, should be prioritized to downregulate the biosynthesis of phytic acid. The review also delves into the biosynthesis and metabolism of phytic acid and elaborates on the mitigation mechanism of phytic acid using biotechnology. The challenges in the application of phytic acid in the food industry were also discussed. This study contributes to a better understanding of the roles phytic acid plays in food and the sustainability and safety of the food industry.

Production of fungal phytases in solid state fermentation and potential biotechnological applications

Phytases are important enzymes used for eliminating the anti-nutritional properties of phytic acid in food and feed ingredients. Phytic acid is major form of organic phosphorus stored during seed setting. Monogastric animals cannot utilize this phytate-phosphorus due to lack of necessary enzymes. Therefore, phytic acid excretion is responsible for mineral deficiency and phosphorus pollution. Phytases have been reported from diverse microorganisms, however, fungal phytases are preferred due to their unique properties. Aspergillus species are the predominant producers of phytases and have been explored widely as compared to other fungi. Solid-state fermentation has been studied as an economical process for the production of phytases to utilize various agro-industrial residues. Mixed substrate fermentation has also been reported for the production of phytases. Physical and chemical parameters including pH, temperature, and concentrations of media components have significantly affected the production of phytases in solid state fermentation. Fungi produced high levels of phytases in solid state fermentation utilizing economical substrates. Optimization of culture conditions using different approaches has significantly improved the production of phytases. Fungal phytases are histidine acid phosphatases exhibiting broad substrate specificity, are relatively thermostable and protease-resistant. These phytases have been found effective in dephytinization of food and feed samples with concomitant liberation of minerals, sugars and soluble proteins. Additionally, they have improved the growth of plants by increasing the availability of phosphorus and other minerals. Furthermore, phytases from fungi have played an important roles in bread making, semi-synthesis of peroxidase, biofuel production, production of myo-inositol phosphates and management of environmental pollution. This review article describes the production of fungal phytases in solid state fermentation and their biotechnological applications.

Unraveling the potential of bacterial phytases for sustainable management of phosphorous

Phosphorous actively participates in numerous metabolic and regulatory activities of almost all living organisms including animals and humans. Therefore, it is considered as an essential macronutrient required supporting their proper growth. On contrary, phytic acid (PA), an antinutritional substance, is widely known for its strong affinity to chelate essential mineral ions including PO4 3- , Ca2+ , Fe2+ , Mg2+ , and Zn2+ . Being one the major reservoir of PO4 3- ions, PA has great potential to bind PO4 3- ions in diverse range of foods. Once combined with P, PA transforms into an undigested and insoluble complex namely phytate. Produced phytate leads to a notable reduction in the bioavailability of P due to negligible activity of phytases in monogastric animals and humans. This highlights the importance and consequent need of enhancement of phytase level in these life forms. Interestingly, phytases, catalyzing the breakdown of phytate complex and recycling the phosphate into ecosystem to its available form, have naturally been reported in a variety of plants and microorganisms over past few decades. In pursuit of a reliable solution, the focus of this review is to explore the keynote potential of bacterial phytases for sustainable management of phosphorous via efficient utilization of soil phytate. The core of the review covers detailed discussion on bacterial phytases along with their widely reported applications viz. biofertilizers, phosphorus acquisition, and plant growth promotion. Moreover, meticulous description on fermentation-based strategies and future trends on bacterial phytases have also been included.

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.

Current research trends on cosmetic microplastic pollution and its impacts on the ecosystem: A review

Since the advent of microplastics, it has become a vital component, directly or indirectly, in our daily lives. With advancements in their use, microplastics have become an integral part of personal care, cosmetics, and cleaning products (PCCPs) and emerged as a domestic source of environmental pollution. Over the years, researchers have ascertained the harmful effects of microplastics on the environment. In this context, the assessment and monitoring of microplastics in PCCPs require considerable attention. In addition, it raises concern regarding the need to develop innovative, sustainable, and environmentally safe technologies to combat microplastic pollution. Therefore, this review is an endeavor to uncover the fate, route and degradation mechanism of cosmetic microplastics. In addition, the major technological advancement in cosmetic microplastic removal and the steps directed toward mitigating cosmetic microplastic pollution are also discussed.