This Research Topic is the second volume of the 'Community series-Extremophiles: Microbial Genomics and Taxogenomics'. Please see the first volume here. Extreme habitats exist across the globe and span over three quarters of our planet. They can be widely different from a physical-chemical perspective as they include diverse types of extreme, such as temperature, pH, salinity, radiation, pressure, low water activity, low nutrient availability, etc. Organisms capable of adjusting, surviving, or thriving in those habitats, which are so hostile that they were previously thought to be adverse or lethal for life, are called “extremophiles”.

The great diversity of microbial life is the remaining major reservoir of unknown biological diversity on earth. To understand this vast, but largely unperceived diversity with its untapped genetic, enzymatic and industrial potential, microbial systematics is undergoing a revolutionary change in its approach to describe novel taxa based on genomic/envirogenomic information. The characterization of an organism is no longer bounded by methodological barriers, and it is now possible to fully sequence the whole genome of a strain to study individual genes, or to examine the genetic information by using different techniques. In fact, application of genomics is helping not only to provide a better understanding of the boundaries of genera and higher levels of classification, but also to refine our definition of the species concept. In addition, increased understanding of phylogeny is allowing to predict the genetic potential of microorganisms for biotechnological applications and adaptation to environmental changes. The present Research Topic on “Microbial Taxonomy, Phylogeny and Biodiversity” compiles a collection of papers covering the use of genomic sequence data in microbial taxonomy and systematics, including evolutionary relatedness of microorganisms; application of comparative genomics in systematic studies; or metagenomic approaches for biodiversity studies. We hope that this eBook incentives and encourages researchers for future discussions on microbial taxonomy and phylogenetics.

Various groups of microorganisms - bacteria, archaea, algae and even fungi - have adapted to a life in a hypersaline environment. Halophilic Microorganisms explores the many-fold aspects of life under these extreme conditions. Several contributions analyze the microbial communities in different hypersaline environments such as salterns, soda lakes, and the Dead Sea or salt sediments. Reviews of their biodiversity, phylogeny, and genetics are given as well as of the diverse adaptation strategies of salt-tolerant or salt-requiring microorganisms. Microorganisms that have adapted to moderate salt concentrations or to habitats with drastic fluctuations are also treated in addition to the extreme halophiles. Their physiological, biochemical and molecular mechanisms developed in response to salinity and high osmotic pressure as well as current and future biotechnological applications are presented.

This informative and up-to-date book is an invaluable review on current research in astrobiology and is an essential acquisition for anyone involved in this cross-disciplinary field.

In this book, the latest tools available for functional metagenomics research are described.This research enables scientists to directly access the genomes from diverse microbial genomes at one time and study these “metagenomes”. Using the modern tools of genome sequencing and cloning, researchers have now been able to harness this astounding metagenomic diversity to understand and exploit the diverse functions of microorganisms. Leading scientists from around the world demonstrate how these approaches have been applied in many different settings, including aquatic and terrestrial habitats, microbiomes, and many more environments. This is a highly informative and carefully presented book, providing microbiologists with a summary of the latest functional metagenomics literature on all specific habitats.

Volume 41 of Methods in Microbiology is a methods book designed to highlight procedures that will revitalize the purposes and practices of prokaryotic systematics. This volume will notably show that genomics and computational biology are pivotal to the new direction of travel and will emphasise that new developments need to be built upon historical good practices, notably the continued use of the nomenclatural type concept and the requirement to deposit type strains in at least two service culture collections in different countries.