Abstract
Pick an organism, and consider what strategy it takes to wait out unfavorable conditions in some sort of quiescent state. Which genes are regulated? When? What are the signals? How are they transduced? These questions have been answered numerous times by nature, and one solution, in bacteria, is the subject of this book.
The Bacterial Spore: From Molecules to Systems provides a technical and densely referenced overview of endospores in Firmicute bacteria. This compendium is organized into 5 sections: (1) an overview of the main spore-forming genera Bacillaceae and Clostridium, (2) Bacillus subtilis as the exemplar species, (3) Bacillus anthracis, (4) the Clostridia, and (5) practical technological applications for spore surface display and soil remediation. While the authors focus on the most well-studied species of Bacillus and Clostridium, the trove of biological curiosities found in the phylum are mentioned throughout the book: extremophiles in evolution, unusual nonmodel spore formers, spores that are millions of years old, and even the relationship between high pressure and the potential for spore survival on Mars. The chapter “Spore Resistance Properties” covers the variety of areas of applied interest, including the increasing human health hazards posed by endospores.
This is an excellent book for those who want an in-depth genetic analysis of spore biology. Contributors closely associate properties about the spore system with the molecular and biochemical methodologies used to elucidate them, and this treatment will be invaluable to investigators. The chapters have a common emphasis on the genes and operons that form the basis for classification and that are integral to spore formation. The contributors furnish a foundation for future investigation by providing numerous genome databases and resources for classification.
This text provides a valuable inventory of scientific contributions describing bacterial spore biology. Written and edited by leading experts, The Bacterial Spore is as appropriate for the layperson as any other comprehensive review paper published in Microbiology Spectrum, and some background knowledge is assumed. The intended audience for the book is scholars from a variety of scientific disciplines who are seeking a comprehensive primer on spore formation and biology that goes beyond the basic textbook approach. A variety of visuals support and depict the information, from microscopy images to full color schematics. Commonly, the presence or absence of genes or operons jumps out by way of encyclopedic tables and phylogenetic trees. Each chapter is a self-contained unit of information, and one can take a more targeted approach and choose which chapters to read. The more casual reader can count on popular science tidbits that are noted throughout and typically toward the beginning of each chapter, as the main authors summarize the background for a given chapter’s topic.
I enjoyed how contributors cited and described early discoveries and the pioneering work to frame the state of the art. For example, chapters laying the foundation on spore-forming biology have references that span >100 years. In contrast, the chapter on the phylogeny of Bacillus cereus sensu lato spans 20 years to cover what was learned with the advent of more sensitive genome-mapping techniques. (Spoiler alert: the newer techniques confirmed the initial 16s rRNA analyses.)
I found it very interesting to read this review of spore systems as they pertain to the classification of B cereus sensu lato. The distinct phenotypic niches of the 3 main species—a human pathogen (B anthracis), a biopesticide (B thuringiensis), and a common soil inhabitant (B cereus)—have driven somewhat arbitrary taxonomic designations. The main point of the chapter on the phylogeny of B cereus sensu lato is that group members are genetically more similar than their phenotypes would indicate, and some are but a few plasmids apart. As a biosafety professional and sometime spectator of the Select Agent Program, I find this timely: the Department of Human Health Services, as of April 12, 2017, has designated Bacillus cereus Biovar athracis a Tier 1 Select Agent, it is now regulated like B anthracis, and the goal is to prevent its misuse. Results of the analyses of isolates with newer and higher-resolution techniques converged to support the idea that the phylogeny of Bacillus cereus sensu lato has a clonal structure. The findings indicate that B cereus isolates have a similar basal genomic structure and size and suggests that the movement of pathogenic elements remains an ongoing phenomenon in the species. These notions support the idea that the B cereus sensu lato group can be transformed into new pathogenic lineages under the right set of circumstances. The contributors note as an example the B cereus isolates that have acquired pXO1 and/or pXO2.