The widespread occurrence and adverse environmental and health-related impacts of various types of emerging contaminants (ECs) have become an issue of high concern. With ever increasing scientific knowledge, socio-economic awareness, health-related problems and ecological apprehensions, people are more concerned about the widespread ECs, around the globe. Among ECs, biologically active compounds from pharmaceutical, cosmeceutical, biomedical, personal care products (PPCPs), endocrine-disrupting chemicals (EDCs), and flame-retardants are of paramount concern. The presence and persistence of ECs in water bodies are of continued and burning interest, worldwide. Various types of ECs are being discharged knowingly/unknowingly with/without partial treatments into the aquatic environments that pose serious health issues and affects the entire living ecosystem. So far, various approaches have been developed for ECs degradation and removal to diminish their adverse impact. Many previous and/or ongoing studies have focused on contaminants degradation and efficient removal via numerous treatment strategies, i.e. (1) physical, (2) chemical and (3) biological. However, the experimental evidence is lacking to enable specific predictions about ECs mechanistic degradation and removal fate across various in-practice systems. In this context, the deployment oxidoreductases such as peroxidases (lignin peroxidases, manganese-dependent peroxidases, and horseradish peroxidase), aromatic dioxygenases, various oxygenases, laccases, and tyrosinases have received considerable research attention. Immobilization is highlighted as a promising approach to improve enzyme catalytic performance and stabilization, as well as, to protect the three-dimensional structure of the enzyme against the undesirable consequences of harsh reaction environment. This work overviews the current and state-of-the-art critical aspect related to hazardous pollutants at large and ECs in particular by the immobilized oxidoreductase enzymes. The first part of the review focuses on the occurrence, physiochemical behavior, potent sources and significant routes of ECs. Following that, environmentally-related adverse impacts and health-related issues of ECs are discussed in the second part. In the third part, biodegradation and removal strategies with a comparative overview of several conventional vs. non-conventional methods are presented briefly. The fourth part majorly focuses on operational modes of different oxidoreductase enzyme-based biocatalytic processes for the biodegradation and biotransformation of a wide array of harmful environmental contaminants. Finally, the left behind research gaps, concluding remarks as well as future trends and recommendations in the use of carrier-immobilized oxidoreductases for environmental perspective are also discussed.

In the 21st century, with ever-increasing consciousness and social awareness, researchers must tackle the microbial infections that pose a major threat to human safety. For many reasons, the emergence/re-emergence of threatening pathogens has increased and poses a serious challenge to health care services. Considering the changing dynamics of 21st-century materials with medical potentialities, the integration of bioactive agents into materials to engineer antibacterial matrices has received limited attention so far. Thus, antimicrobial active conjugates are considered potential candidates to eradicate infections and reduce microbial contaminations in healthcare facilities. In this context, eco-friendly and novel conjugates with antimicrobial, antibiofilm, and anticancer potentialities were developed using biogenic silver nanoparticles (AgNPs) from Convolvulus arvensis (C. arvensis) extract and chitosan (CHI). A range of instrumental and imaging tools, i.e., UV-Vis and FTIR spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX), and X-ray diffraction (XRD), were employed to characterize the freshly extracted C. arvensis AgNPs. Biogenic AgNPs obtained after a 24-h reaction period were used to engineer CHI-based conjugates and designated as CHI‒AgNPs1 to CHI‒AgNPs5, subject to the C. arvensis AgNPs concentration. After the stipulated loading period, 92% loading efficiency (LE) was recorded for a CHI‒AgNPs3 conjugate. Gram+ and Gram- bacterial isolates, i.e., Staphylococcus aureus, and Escherichia coli, were used to test the antibacterial activities of newly developed CHI‒AgNPs conjugates. In comparison to the control sample with bacterial cell count 1.5 × 10⁸ CFU/mL, a notable reduction in the log values was recorded for the CHI‒AgNPs3 conjugate. The antibiofilm potential of CHI‒AgNPs conjugates was tested against Pseudomonas aeruginosa. Moreover, the CHI‒AgNPs3 conjugate also showed substantial cytotoxicity against the MCF-7 (breast cancer) cell line. In summary, the newly engineered CHI‒AgNPs conjugates with antibacterial, antibiofilm, and anticancer potentialities are potential candidate materials for biomedical applications.

L-tryptophan is an essential aromatic amino acid that has been widely used in medicine, food, and animal feed. Microbial biosynthesis of L-tryptophan through metabolic engineering approaches represents a sustainable, cost-effective, and environmentally friendly route compared to chemical synthesis. In particular, metabolic pathway engineering allows enhanced product titers by inactivating/blocking the competing pathways, increasing the intracellular level of essential precursors, and overexpressing rate-limiting enzymatic steps. Based on the route of the L-tryptophan biosynthesis pathway, this review presents a systematic and detailed summary of the contemporary metabolic engineering approaches employed for L-tryptophan production. In addition to the engineering of the L-tryptophan biosynthesis pathway, the metabolic engineering modification of carbon source uptake, by-product formation, key regulatory factors, and the polyhydroxybutyrate biosynthesis pathway in L-tryptophan biosynthesis are discussed. Moreover, fermentation bioprocess optimization strategies used for L-tryptophan overproduction are also delineated. Towards the end, the review is wrapped up with the concluding remarks, and future strategies are outlined for the development of a high L-tryptophan production strain.

This study was carried out to screen a potential probiotic microbe with broad-spectrum antagonistic activity against food-borne pathogens and identify the antimicrobial compounds. Based on morphological and molecular analysis, a new Bacillus strain with the ability to produce effective antimicrobial agents was isolated from the breeding soil of earthworms and identified as having a close evolutionary footprint to Bacillus amyloliquefaciens. The antimicrobial substances produced by B. amyloliquefaciens show effective inhibition of Aspergillus flavus and Fusarium oxysporum in an agar diffusion assay. Antimicrobial agents were identified as a series of fengycin and its isoforms (fengycin A and fengycin B) after being submitted to RT-HPLC and MALDI-TOF MS analyses. To evaluate the probiotic activity of the B. amyloliquefaciens, antibiotic safety and viability of the isolated strain in a simulated gastrointestinal environment were carried out. The safety test result revealed that strain LPB-18 is susceptible to multiple common antibiotics. Moreover, acidic condition and bile salts assay were carried out, and the results revealed that it couble be a potential probiotic microbe B. amyloliquefaciens LPB-18 is good choice for biological strains in agricultural commodities and animal feedstuffs.