Novel Insights Into the Sulfated Glucuronic Acid-Based Anti-SARS-CoV-2 Mechanism of Exopolysaccharides From Halophilic Archaeon Haloarcula hispanica.

The pandemic caused by SARS-CoV-2 is the most widely spread disease in the 21st century. Due to the continuous emergence of variants across the world, it is necessary to expand our understanding of host-virus interactions and explore new agents against SARS-CoV-2. In this study, it was found exopolysaccharides (EPSs) from halophilic archaeon Haloarcula hispanica ATCC33960 can bind to the spike protein of SARS-CoV-2 with the binding constant KD of 2.23 nM, block the binding of spike protein to Vero E6 and bronchial epithelial BEAS-2B cells, and inhibit pseudovirus infection. However, EPSs from the gene deletion mutant △HAH_1206 almost completely lost the antiviral activity against SARS-CoV-2. A significant reduction of glucuronic acid (GlcA) and the sulfation level in EPSs of △HAH_1206 was clearly observed. Our results indicated that sulfated GlcA in EPSs is possible for a main structural unit in their inhibition of binding of SARS-CoV-2 to host cells, which would provide a novel antiviral mechanism and a guide for designing new agents against SARS-CoV-2.

Emerging Trends in Pullulan-Based Antimicrobial Systems for Various Applications.

Global reports on multidrug resistance (MDR) and life-threatening pathogens such as SARS-CoV-2 and Candida cruris have stimulated researchers to explore new antimicrobials that are eco-friendly and economically viable. In this context, biodegradable polymers such as nisin, chitin, and pullulan play an important role in solving the problem. Pullulan is an important edible, biocompatible, water-soluble polymer secreted by Aureobasidium pullulans that occurs ubiquitously. It consists of maltotriose units linked with α-1,6 glycosidic bonds and is classed as Generally Regarded as Safe (GRAS) by the Food and Drug Administration (FDA) in the USA. Pullulan is known for its antibacterial, antifungal, antiviral, and antitumor activities when incorporated with other additives such as antibiotics, drugs, nanoparticles, and so on. Considering the importance of its antimicrobial activities, this polymer can be used as a potential antimicrobial agent against various pathogenic microorganisms including the multidrug-resistant (MDR) pathogens. Moreover, pullulan has ability to synthesize biogenic silver nanoparticles (AgNPs), which are remarkably efficacious against pathogenic microbes. The pullulan-based nanocomposites can be applied for wound healing, food packaging, and also enhancing the shelf-life of fruits and vegetables. In this review, we have discussed biosynthesis of pullulan and its role as antibacterial, antiviral, and antifungal agent. Pullulan-based films impregnated with different antimicrobials such as AgNPs, chitosan, essential oils, and so on, forming nanocomposites have also been discussed as natural alternatives to combat the problems posed by pathogens.

Occurrence, fates and potential treatment approaches for removal of viruses from wastewater: A review with emphasis on SARS-CoV-2.

The world is combating the emergence of Coronavirus disease 2019 (COVID-19) caused by novel coronavirus; severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Further, due to the presence of SARS-CoV-2 in sewage and stool samples, its transmission through water routes cannot be neglected. Thus, the efficient treatment of wastewater is a matter of utmost importance. The conventional wastewater treatment processes demonstrate a wide variability in absolute removal of viruses from wastewater, thereby posing a severe threat to human health and environment. The fate of SARS-CoV-2 in the wastewater treatment plants and its removal during various treatment stages remains unexplored and demands immediate attention; particularly, where treated effluent is utilised as reclaimed water. Consequently, understanding the prevalence of pathogenic viruses in untreated/treated waters and their removal techniques has become the topical issue of the scientific community. The key objective of the present study is to provide an insight into the distribution of viruses in wastewater, as well as the prevalence of SARS-CoV-2, and its possible transmission by the faecal-oral route. The review also gives a detailed account of the major waterborne and non-waterborne viruses, and environmental factors governing the survival of viruses. Furthermore, a comprehensive description of the potential methods (physical, chemical, and biological) for removal of viruses from wastewater has been presented. The present study also intends to analyse the research trends in microalgae-mediated virus removal and, inactivation. The review also addresses the UN SDG 'Clean Water and Sanitation' as it is aimed at providing pathogenically safe water for recycling purposes.