Actinobacteria are well-known producers of a vast array of secondary metabolites. Compared with actinobacteria from temperate habitats, the community structure, diversity, biological activities and mechanisms of environmental adaptation of those actinobacteria in special and extreme environments are relatively unstudied and unclear, and their functions and utilization are even less reported. These actinobacteria are potential new sources of novel natural products and functions for exploitation in medicine, agriculture, and industry. Recent advances in cultivation, DNA sequencing technologies and -omics methods have greatly contributed to the rapid advancement of our understanding of microbial diversity, taxonomy, function and they interactions with environment. Following the success of the Research Topic “Actinobacteria in special and extreme habitats: diversity, functional roles and environmental adaptations” organized in 2015, we are happy to launch a second edition. This Research Topic second edition, comprising reviews and original articles, highlights recent discoveries on rare actinobacterial diversity, phylogenomics, biological compounds, ecological function and environmental adaptations of actinobacteria in special and extreme habitats; and broadens our knowledge of actinobacterial diversity and their ecophysiological function.

Actinobacteria are highly diverse prokaryotes that are ubiquitous in soil, freshwater and marine ecosystems. Although various studies have focused on the ecology of this phylum, data are still scant on the diversity, abundance and ecology of actinobacteria endemic to special and extreme environments, such as gut, plant, alkaline saline soil, deep sea sediments, hot springs and other habitats. Actinobacteria are well-known producers of a vast array of secondary metabolites, many of which have useful applications in medicine and agriculture. Furthermore, actinobacteria also have diverse functions in different environments apart from antibiotic production. For example, actinobacteria are reported to contribute to the break-down and recycling of organic compounds. They play a significant role in fixation of nitrogen, improvement plant growth, biodegradation, bioremediation and environmental protection. Therefore, understanding the actinobacterial diversity and distribution in such special environments is important in deciphering the ecological roles of these microorganisms and for biotechnological bioprospecting. Recent advances in cultivation, DNA sequencing technologies and -omics (metagenomics, metaproteomics etc) methods have greatly contributed to the rapid advancement of our understanding of microbial diversity, function and they interactions with environment. Furthermore, comparative genomic studies can provide overall information about actinobacterial speciation, evolution, metabolism and environment adaptation mechanisms. This research topic comprising reviews and original articles highlights the recent advances regarding the unexpectedly diverse/rare group of actinobacteria with special selective isolation methods or culture-independent methods, as well as their biological activities, ecophysiologica function and mechanisms from diverse special and extreme environments.

Green Synthesis of Silver Nanomaterials illustrates how to biologically scale up silver nanoparticle synthesis. This book covers green synthesis of silver nanomaterials, via plants, agricultural waste, fungi, and microorganisms. Sections cover the synthesis and characterization of chemical and green synthesis, various types of silver nanomaterialism, the ability of different fungal species, such as filamentous fungi, to produce silver nanoparticles, the microbial synthesis of silver NMs, biosynthesis mechanisms, toxicity, fate and commercialization. As examples, greener pathways and mechanisms, toxicity of silver nanoparticles in aquatic life and in natural eco-systems, and strategies for the scaling up of green-synthesized nanomaterials are discussed. With the extended work in enhancing nanomaterials synthesis performance, and discovering their biomedical, environmental, and agricultural applications, it is hoped that the execution of these methods on a large scale and their industrial applications in different fields will take place in the near future. - Assesses the impact of a large variety of silver-based nanostructures in the biomedical, environmental and agri-food sectors - Discusses the major synthesis methods used for effectively processing plant-based silver nanoparticles - Outlines the potential and major challenges for adopting green synthesis methods on a mass scale

This new book analyzes the exploration and sustainable valorization of natural resources from the arid zones, putting special emphasis on the challenges that the industry faces in an era of sustainable development and ecological conservation programs. The volume describes the geographic and climatic characteristics as well as the natural resources from arid zones, divided into three main groups: a) microbiological resources as biotechnological tools and change agents to produce and/or obtain compounds with industrial or medicinal applications; b) plants as an important source of principal compounds or subproducts produced by natural adaptation to the extreme environmental conditions; and c) animal resources, which includes insects, animal residues, products or subproducts derived from animal sources, as well as poisons. The authors focus on the processes or bioprocesses used in the valorization and transformation of these three main groups for research purposes as well as for biotechnological processing to obtain important compounds for use in various industries. The information provided in this volume, Exploration and Valorization of Natural Resources from Arid Zones, can be used as reference for investigation, training, and education, and also as main tool in under- and postgraduate university education on the sustainable uses of resources from arid zones.

Publisher’s note: This is a 2nd edition due to an article retraction.

This book ‘Extremophiles: Wastewater and Algal Biorefinery’ explores the potential of extremophiles/extremotolerant organisms in wastewater treatment, biorefining of algal biomass and in the treatment of industrial waste effluent. The book provides a holistic overview about the current status of extremophiles in waste water treatment and various industrial processes. The chapters comprehensively cover the scientific and research findings on various industrial applications of extremophiles such as biofuels, extremozymes, electricity generation, biofilms, microbial corrosion and waste water treatment etc. This book is an integrated source of literature for the scientists, engineers, academicians, and students working in the area of extremophiles, microbial technology and biorefinery.

Development in Wastewater Treatment Research and Processes: Microbial Degradation of Xenobiotics through Bacterial and Fungal Approach covers the active and applicable role that bacteria and fungi play in the degradation of xenobiotic compounds from the environment. The book gives up-to-date information on recent advancements in the field of environmental xenobiotics and how they disturb a plant's metabolism. The book also gives information on aerobic and anaerobic degradation of xenobiotic compounds through bacteria or fungi and/or a combined approach. Finally, the book covers the characteristics of environmental microbiology, biochemical engineering, agricultural microbiology, environmental engineering, and soil bioremediation. - Emphasizes up-to-date research on the microbial degradation of xenobiotic compounds through a bacterial-fungal approach - Covers multidisciplinary features of environmental microbiology, biochemical engineering, agriculture microbiology, environmental engineering and soil bioremediation - Includes sections on aerobic and anaerobic degradation - Presents the significance of the bacterial-fungal role and their metabolic activities in the digestion of xenobiotic compounds - Focuses on the most recent developments in environmental biotechnology to enhance the action of the bacterial-fungal systems in the remediation of xenobiotic compounds

The world of halophiles is quite diverse and their representatives in three domains of life i.e. archaea, bacteria and eukarya. They are found all over the small subunit rRNA based tree of life and these micro-organisms are adapted to salt concentration up to saturation hence able to grow at >300g/l Nacl concentration. Their metabolic diversity is high as well encompassing oxygenic and anoxygenic phototrophs, aerobic heterotrophs, denitrifiers, sulphate reducers, fermenters and methanogens. The proteins of halophiles are magnificently engineered to function in a milieu containing 2-5M salt that encodes genes represent a valuable repository and resource for reconstruction and visualizing processes of habitat selection and adaptive evolution. Search for new enzymes endowed with novel activities and enhanced stability continues to be desirable purpose for important commercial production of biotechnological significance. These poly extremophiles proved excellent source of enzymes and metabolites possessing inherent ability to function in extreme conditions of high salt, alkaline pH and facilitating catalysis for industrial application in food processing, industrial bioconversion, bioremediation etc. In fact, it has just begun to realize the great potential and true extent of diversity and suitable applications if explored them judiciously. This book highlights current applications and research on halophiles to provide a timely overview. Chapters are written by expert authors from around the world and include topics of varied importance which include their role to play in enzyme production, restoration of soil fertility and plant growth , antimicrobial and biocatalytic potential, biomolecules in nanotechnology and aspects of quorum sensing. The book is divided into three sections, dealing with biodiversity, biotechnology and sustainable exploitation of halophiles. This major new work represents a valuable source of information to all those scientists interested in microorganisms in general and extremophiles in particular with respect to their innovative products and applications.