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Intro -- Dedication -- Series Preface -- Volume Preface -- Contents -- Part I: Understanding the Basis of Symbiotic Associations -- Chapter 1: Symbiotic Associations: All About Chemistry -- References -- Part II: Associations Between Microbes -- Chapter 2: Phage Conversion and the Role of Bacteriophage and Host Functions in Regulation of Diphtheria Toxin Production by C... -- 2.1 Ubiquitous Bacteriophages and Their Roles in Evolution of Bacterial Genomes -- 2.2 Phage Conversion and Toxinogenicity in Medically Important Bacterial Pathogens -- 2.3 A Brief History of Corynebacterium diphtheriae -- 2.4 Phage Conversion and Toxinogenicity in C. diphtheriae -- 2.5 Establishment and Maintenance of Lysogeny by beta- and Related Corynephages -- 2.6 Phage Conversion and Toxinogenicity in Other Corynebacterium spp. -- 2.7 Biosynthesis, Structure, and Mode of Action of Diphtheria Toxin -- 2.8 Regulation of Diphtheria Toxin Production -- 2.9 Recent Advancements in the Development of Genetic Tools for Corynebacterium spp. -- 2.10 Summary -- References -- Chapter 3: Syntrophic Growth of Symbiobacterium in Association with Free-Living Bacteria -- 3.1 Introduction -- 3.2 Unique Properties of S. thermophilum -- 3.2.1 Invisibility -- 3.2.2 Taxonomic Ambiguity -- 3.2.3 Easy Accessibility -- 3.3 Complexity of Growth Requirements -- 3.3.1 Need for Sensitive Growth Measurement -- 3.3.2 Positive Factors -- 3.3.3 Negative Factors -- 3.4 Insights from CO2 Requirements -- 3.4.1 Dispensability of Carbonic Anhydrase -- 3.4.2 CO2 Sensing -- 3.5 Future Perspectives -- References -- Part III: Associations Between Microbes and Plants -- Chapter 4: The Mechanism of Symbiotic Nitrogen Fixation -- 4.1 Nitrogen Fixation -- 4.2 Agricultural Fertilization -- 4.3 Rhizobia -- 4.4 Sinorhizobium meliloti Rm1021 -- 4.5 Rhizobium-Legume Symbiosis -- 4.6 Signal Exchange in the Rhizosphere.

Inherited endosymbiotic bacteria from the genera Rickettsia, Wolbachia and Spiroplasma cause the death of male offspring in ladybirds (Coleoptera, Coccinellidae). As a rule, bacteria are transmitted through the cytoplasm of the mother's egg to offspring – vertically. In addition to vertical transfer, there is increasing evidence of horizontal transfer of symbionts between unrelated insect taxa. Insect parasites such as mites can be potential vectors of endosymbiotic bacteria. The parasitic mite Coccipolipus hippodamiae (McDaniel Morrill, 1969) (Acarina: Podapolipidae) occurs in natural populations of Coccinellidae. In this work, the ability of C. hippodamiae to become infected with Wolbachia and Spiroplasma from hosts and to spread bacteria among coccinellid beetles was proven for the first time.

11 páginas, 3 figuras, 2 tablas. ; In temperate seas, both bacterioplankton communities and invertebrate lifecycles follow a seasonal pattern. To investigate whether the bacterial community associated with the Mediterranean ascidian Didemnum fulgens exhibited similar variations, we monitored its bacterial community structure monthly for over a year using terminal restriction fragment length polymorphism and clone library analyses based on a nearly full length fragment of the 16SrRNA gene. D. fulgens harbored a bacterial consortium typical of ascidians, including numerous members of the phylum Proteobacteria, and a few members of the phyla Cyanobacteria and Acidobacteria. The overall bacterial community in D. fulgens had a distinct signature from the surrounding seawater and was stable overtime and across seasonal fluctuations in temperature. Bacterial symbionts were also observed around animal cells in the tunic of adult individuals and in the inner tunic of D. fulgens larvae by transmission electron microscopy. Our results suggest that, as seen for sponges and corals, some species of ascidians host stable and unique bacterial communities that are at least partially inherited by their progeny by vertical transmission. ; This research was funded by the Marie Curie International Reintegration Grant FP7-PEOPLE-2010-RG277038 within the 7th European Community Framework Program, the Spanish Government projects: MARSYMBIOMICSC TM2013-43287- P and CHALLENGENCTM 2013-48163; and the Catalan Government grant 2014SGR-336 for Consolidated Research Groups. ; Peer reviewed

19 páginas, 6 figuras, 4 tablas. ; Microbial symbionts form abundant and diverse components of marine sponge holobionts, yet the ecological and evolutionary factors that dictate their community structure are unresolved. Here, we characterized the bacterial symbiont communities of three sympatric host species in the genus Ircinia from the NW Mediterranean Sea, using electron microscopy and replicated 16S rRNA gene sequence clone libraries. All Ircinia host species harbored abundant and phylogenetically diverse symbiont consortia, comprised primarily of sequences related to other sponge-derived microorganisms. Community-level analyses of bacterial symbionts revealed host species-specific genetic differentiation and structuring of Ircinia-associated microbiota. Phylogenetic analyses of host sponges showed a close evolutionary relationship between Ircinia fasciculata and Ircinia variabilis, the two host species exhibiting more similar symbiont communities. In addition, several bacterial operational taxonomic units were shared between I. variabilis and Ircinia oros, the two host species inhabiting semi-sciophilous communities in more cryptic benthic habitats, and absent in I. fasciculata, which occurs in exposed, high-irradiance habitats. The generalist nature of individual symbionts and host-specific structure of entire communities suggest that: (1) a 'specific mix of generalists' framework applies to bacterial symbionts in Ircinia hosts and (2) factors specific to each host species contribute to the distinct symbiont mix observed in Ircinia hosts. ; This research was supported by the Spanish Government projects CTM2010-17755 and CTM2010-22218 and by the US National Science Foundation under grant 0853089. ; Peer reviewed

Copyright © 2015 Travis et al. ACKNOWLEDGMENTS We thank Gillian Campbell, Pauline Young, Karen Garden, and Sylvia Duncan for contributing to this work, which was supported by Scottish Government RESAS (Rural and Environmental Sciences and Analytical Services). ; Peer reviewed ; Publisher PDF

11 pages, 5 figures, 1 table, supplementary information https://doi.org/10.1038/s41396-021-00900-6 ; Bacteriophages (phages) are ubiquitous elements in nature, but their ecology and role in animals remains little understood. Sponges represent the oldest known extant animal-microbe symbiosis and are associated with dense and diverse microbial consortia. Here we investigate the tripartite interaction between phages, bacterial symbionts, and the sponge host. We combined imaging and bioinformatics to tackle important questions on who the phage hosts are and what the replication mode and spatial distribution within the animal is. This approach led to the discovery of distinct phage-microbe infection networks in sponge versus seawater microbiomes. A new correlative in situ imaging approach ('PhageFISH-CLEM') localised phages within bacterial symbiont cells, but also within phagocytotically active sponge cells. We postulate that the phagocytosis of free virions by sponge cells modulates phage-bacteria ratios and ultimately controls infection dynamics. Prediction of phage replication strategies indicated a distinct pattern, where lysogeny dominates the sponge microbiome, likely fostered by sponge host-mediated virion clearance, while lysis dominates in seawater. Collectively, this work provides new insights into phage ecology within sponges, highlighting the importance of tripartite animal-phage-bacterium interplay in holobiont functioning. We anticipate that our imaging approach will be instrumental to further understanding of viral distribution and cellular association in animal hosts ; We acknowledge funding by the DFG CRC1182 to UH (TPC4.3), TL (TPC4.2). MTJ was supported by a grant of the German Excellence Initiative to the Graduate School of Life Sciences, University of Wuerzburg, and a Young Investigator Award of the CRC1182. SMM was supported by the Studienstiftung des Deutschen Volkes (German Academic Scholarship Foundation). CS was supported by the grants DFG STI700/1-1 and GRK2581 (P6). MR was supported by the Spanish Government grant (RTI2018-094187-B100) and 'Generalitat de Catalunya' research group grant (2017SGR1011). BED was supported by the Netherlands Organisation for Scientific Research (NWO) Vidi grant 864.14.004 and by the European Research Council (ERC) Consolidator grant 865694: DiversiPHI. /./ Open Access funding enabled and organized by Projekt DEA ; With the funding support of the 'Severo Ochoa Centre of Excellence' accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI) ; Peer reviewed

Acknowledgments The authors would like to thank Andrew Gewirtz (Georgia State University, Atlanta, GA, USA) and Adam Cunningham (University of Birmingham, Edgbaston, Birmingham, UK) for generously providing the germ-free and conventional TLR5KO mice, respectively. The authors also wish to acknowledge a significant contribution to the inception of the work, experimental work, interpretation of results, and writing of the manuscript by Denise Kelly, as well as the support from RESAS (Rural and Environmental Science and Analytical Services) of the Scottish Government. EM and VF were supported by the Marie Curie Initial training network Fellowships funded by the EU (grant #215532). The authors acknowledge a generous support of Prof. Harry Flint and Dr. Sylvia Duncan in the microbiological part of this work. The skilled technical support of Gillian Campbell and Pauline Young at RINH Genomics is also gratefully acknowledged. ; Peer reviewed ; Publisher PDF