Insights into the Biosynthesis of Nanoparticles by the Genus Shewanella.

The exploitation of microorganisms for the fabrication of nanoparticles (NPs) has garnered considerable research interest globally. The microbiological transformation of metals and metal salts into respective NPs can be achieved under environmentally benign conditions, offering a more sustainable alternative to chemical synthesis methods. Species of the metal-reducing bacterial genus Shewanella are able to couple the oxidation of various electron donors, including lactate, pyruvate, and hydrogen, to the reduction of a wide range of metal species, resulting in biomineralization of a multitude of metal NPs. Single-metal-based NPs as well as composite materials with properties equivalent or even superior to physically and chemically produced NPs have been synthesized by a number of Shewanella species. A mechanistic understanding of electron transfer-mediated bioreduction of metals into respective NPs by Shewanella is crucial in maximizing NP yields and directing the synthesis to produce fine-tuned NPs with tailored properties. In addition, thorough investigations into the influence of process parameters controlling the biosynthesis is another focal point for optimizing the process of NP generation. Synthesis of metal-based NPs using Shewanella species offers a low-cost, eco-friendly alternative to current physiochemical methods. This article aims to shed light on the contribution of Shewanella as a model organism in the biosynthesis of a variety of NPs and critically reviews the current state of knowledge on factors controlling their synthesis, characterization, potential applications in different sectors, and future prospects.

The Escalating Biomedical Waste Management To Control the Environmental Transmission of COVID-19 Pandemic: A Perspective from Two South Asian Countries.

The global pandemic COVID-19 culminated in escalating biomedical waste (BMW) worldwide, and the management authorities are struggling with waste treatment. Bangladesh and India are two densely populated South Asian developing countries with limited resources. Both countries face mass community transmission of the disease, with India facing severe infections and deaths. Predictably, a large population might sum up to a large amount of COVID-19-related BMW. There is also the question of capacity, whether the existing BMW policies and regulations of the regions can manage the BMW strategically driven by the pressure of the pandemic. Here, we have shown a framework leading to further environmental and community transmission of the COVID-19 pandemic if the BMW generated at healthcare facilities and homes is not appropriately managed. The BMW, such as safety suits or personal protective equipment (PPE), masks, gloves, and shields, would likely damage the environment in the long run by creating microplastic pollution. Modification and modernization of the existing policies, plans, and guidelines on the proper management of the hospital and household infectious waste is suggested. Moreover, occupational health and safety assessments for waste management workers at the hospitals are recommended. Installing suitable capacity incinerators and related infrastructures are recommended for appropriate waste management. In the absence of incinerators, the existing industrial furnaces, cement kilns, and mobile incinerators can be used with a rapid impact assessment adhering to the appropriate implementations of the policies and guidelines.

ZnO and CuO nanoparticles: a threat to soil organisms, plants, and human health.

The progressive increase in nanoparticles (NPs) applications and their potential release into the environment because the majority of them end up in the soil without proper care have drawn considerable attention to the public health, which has become an increasingly important area of research. It is required to understand ecological threats of NPs before applications. Once NPs are released into the environment, they are subjected to translocation and go through several modifications, such as bio/geo-transformation which plays a significant role in determination of ultimate fate in the environment. The interaction between plants and NPs is an important aspect of the risk assessment. The plants growing in a contaminated medium may significantly pose a threat to human health via the food chain. Metal oxide NPs ZnO and CuO, the most important NPs, are highly toxic to a wide range of organisms. Exposure and effects of CuO and ZnO NPs on soil biota and human health are critically discussed in this study. The potential benefits and unintentional dangers of NPs to the environment and human health are essential to evaluate and expected to produce less toxic and more degradable NPs to minimize the environmental risk in the future.

Metagenomics: Concept, methodology, ecological inference and recent advances.

Microorganisms constitute two third of the Earth's biological diversity. As many as 99% of the microorganisms present in certain environments cannot be cultured by standard techniques. Culture-independent methods are required to understand the genetic diversity, population structure and ecological roles of the majority of organisms. Metagenomics is the genomic analysis of microorganisms by direct extraction and cloning of DNA from their natural environment. Protocols have been developed to capture unexplored microbial diversity to overcome the existing barriers in estimation of diversity. New screening methods have been designed to select specific functional genes within metagenomic libraries to detect novel biocatalysts as well as bioactive molecules applicable to mankind. To study the complete gene or operon clusters, various vectors including cosmid, fosmid or bacterial artificial chromosomes are being developed. Bioinformatics tools and databases have added much to the study of microbial diversity. This review describes the various methodologies and tools developed to understand the biology of uncultured microbes including bacteria, archaea and viruses through metagenomic analysis.