Meeting report ‘Microbiology 2023: from single cell to microbiome and host’, an international interacademy conference in Würzburg

Abstract On September 20–22 September 2023, the international conference ‘Microbiology 2023: from single cell to microbiome and host’ convened microbiologists from across the globe for a very successful symposium, showcasing cutting-edge research in the field. Invited lecturers delivered exceptional presentations covering a wide range of topics, with a major emphasis on phages and microbiomes, on the relevant bacteria within these ecosystems, and their multifaceted roles in diverse environments. Discussions also spanned the intricate analysis of fundamental bacterial processes, such as cell division, stress resistance, and interactions with phages. Organized by four renowned Academies, the German Leopoldina, the French Académie des sciences, the Royal Society UK, and the Royal Swedish Academy of Sciences, the symposium provided a dynamic platform for experts to share insights and discoveries, leaving participants inspired and eager to integrate new knowledge into their respective projects. The success of Microbiology 2023 prompted the decision to host the next quadrennial academic meeting in Sweden. This choice underscores the commitment to fostering international collaboration and advancing the frontiers of microbiological knowledge. The transition to Sweden promises to be an exciting step in the ongoing global dialogue and specific collaborations on microbiology, a field where researchers will continue to push the boundaries of knowledge, understanding, and innovation not only in health and disease but also in ecology.


Introduction
Learned societies play important roles in disseminating the latest discov eries and de v elopments in their r espectiv e scientific discipline and in organizing a community of scientifically like-minded people .T his is also true for national academies of sciences, which strive to amplify the impact and visibility of the many different disciplines they cover.One instrument for ac hie ving this is or ganizing international meetings in order to bring together thought leaders from a field of interest and enable scientific exchange betw een students, y oung faculty, and established resear chers in that community.On 20-22 September 2023, the national academies of four European countries joined forces to put the spotlight on micr obiology, whic h is one of the most thriving areas of the life sciences and remains a source of unexpected findings and new principles that later find application in biomedicine, biotechnology , and ecology , to name just a few.
The four academies inv olved w ere the German National Academy of Sciences Leopoldina, r epr esented by Jör g Hac ker and Jörg Vogel; the Académie des sciences de l'Institut de France, r epr esented by P ascale Cossart; the British Ro y al Society, represented by David Holden; and the Swedish Kungl.Vetenskapsakademien, r epr esented by Staffan Normark.It was the first time for these four countries to run a joint interacademy conference but not the first time for them to collaborate in the organization of microbiology-centric meetings.In fact, Jörg Hacker and Pascale Cossart organized a FEMS/Leopoldina Symposium 'Emerging Topics in Microbial Pathogenesis' at the Juliusspital in Würzburg in April 2010.This then turned into a meeting series, with the next conference entitled 'The new microbiology' taking place at the Institut de Fr ance, P arison 14-16 May 2012.While the Académie des sciences took the lead, both the Leopoldina and The Ro y al Society w ere inv olved, too (Radoshevich et al. 2012 ).Next, these three academies partnered to organize a conference called 'The New Bacteriology' at the Ro y al Society in London on January 28-19 January 2016 (Cossart et al. 2016 ).Common to all these conferences was that thy aimed to highlight new concepts and approaches that fueled the recent renaissance of microbes as exciting organisms to study.Plans w ere underw ay to hold the next meeting, for which the pr esent or ganizers originall y met in Berlin in April 2019 (Fig. 1 ), to a gr ee on speakers and pr epar e the conference schedule for the y ear after.Ho w e v er, the COVID-19 pandemic starting in spring 2020 thwarted their plans and made it liter all y impossible to firmly fix a date for the next 2 years; while it was the organizers' ambition to secure a list of high-profile international speakers, sometimes unpr edictable tr av el r estrictions made planning very difficult.Yet, as the skies started clearing up in early 2023, they wer e pleasantl y sur prised by the unabated commitment of the invited speakers to come and speak in September that year.This time called 'Microbiology 2023: From single cell to microbiome and host', the conference built on the successful format of previous meetings: starting on Wednesday afternoon and finishing Friday noon, with half-hour speaking slots for a total of 22 invited speakers .T here was plenty of time and opportunity for early car eer r esearc hers to pr esent their work as part of a poster session and to mingle with the speakers as well as attending established scientist.
Before we provide an ov ervie w of the scientific pr ogr amme, we would like to mention that there was more than one reason for the conference to return to Würzburg after Paris and London, and these ultimately relate to the person of Jörg Hacker (Fig. 2 ).To begin with, Hacker served the Leopoldina as President for 10 years, from 2010 to 2020.With Microbiology 2023 the Leopoldina wished to recognize its outgoing President's many contributions in the fields of microbiology, infectious diseases research, and beyond.Mor eov er, Würzbur g boasts a vibr ant comm unity of microbiologists and infectious disease r esearc hers with a critical mass that hardl y matc hed by other places in German y.Hac ker was one of the founding fathers of this comm unity, thr ough both his own re-search into pathogenicity island and genomic and extr ac hr omosomal elements of bacterial pathogens and his visionary activities as the founding director of the Institute of Molecular Infection Biology (IMIB) of the University of Würzburg (1993Würzburg ( -2006)).He also cofounded and led for many years the Würzburg Research Center for Infectious Diseases (ZINF), whose pioneering young investigator pr ogr amme facilitated the early independence of dozens of young scientists fr om bacteriology, par asitology, and fungal biology.Although he left Würzburg almost 20 years ago to serve as the President of the federal Robert Koch Institute, before taking the helm at the Leopoldina, he continued to provide support to the Würzbur g r esearc h comm unity.His advice was crucial in a national competition for ne w r esearc h institutes in 2016, which resulted in the founding the Helmholtz Institute for RNA-based Infection Research (HIRI), Würzburg's first federally funded research institute in the life sciences .Moreo ver, while still in Würzburg, he helped to secure the funds for a new research building which now hosts the IMIB and provided the venue for Microbiology 2023 and its ∼300 participants (Fig. 3 ).

Scientific pr ogr amme
The conference commenced with an opening presentation by Jörg Vogel in his capacity of the local host and director of the IMIB and the HIRI.He introduced his fellow organizers as well as additional invited sessions chairs: Thomas Rudel, Chase Beisel, and Cynthia Sharma (all Würzbur g), Fr anz Narberhaus (Bochum) and Birgitta Henriques Normark (Stoc kholm).Ther e wer e four sessions in total, the first on Wednesda y, two T hursda y morning and afternoon, and the last on Friday morning.Session 1: infection biology and microbiome (Fig.

)
Internal conflicts in Salmonella per sister s Sophie Helaine (Harvard Medical School, Boston, USA) discussed bacterial persistence and how during infection, Salmonella respond to engulfment by macr opha ges by forming many persisters (Helaine et al. 2014 ).These persisters escape the combined action of the antibiotic and host immune defence by adopting a nongrowing state.Sophie presented unpublished data (Moll y Sar gen and Sophie Helaine, unpublished) sho wing ho w DNA damage occurring in persisters while within macr opha ges (Hill et al. 2021 ) induces pr opha ge r eactiv ation in these bacteria that nonetheless a void lysis .She presented that Prophage Competition Elements protect persisters and provided molecular details of activity of RemAIN, one suc h Pr opha ge Competition Element.

Host-microbe interactions underlying colonization resistance
Andreas Bäumler (UC Da vis , USA) described that antibiotic prophylaxis sets the stage for an intestinal Candida albicans bloom (P a ppas et al. 2018 ), but that the resources driving this expansion are incompletely understood.Butyrate-producing Clostridia species maintain epithelial hypoxia but are depleted by antibiotic treatment (Byndloss et al. 2017 ).Notably, increased epithelial oxygenation after Clostridia depletion dr ov e a postantibiotic C. albicans expansion.Commensal Clostridia species could be replaced functionally with 5-aminosalicylic acid (5-ASA), which activ ated mitoc hondrial oxygen consumption to r estor e epithelial hypoxia and reinstate colonization r esistance a gainst C. albicans (Sav a ge et al. 2023 ).T hus , 5-ASA treatment is a nonbiotic intervention that restores colonization resistance against C. albicans .

Micr obiome d ynamics during infection
Andr e w Goodman (Yale School of Medicine, USA) presented recent work c har acterizing interbacterial interactions in the gut microbiome .T he seminar focused on contact-dependent antagonism, highlighting examples in vitro, in animal models, and inferences from human metagenomic data that each illustr ate the r ole of these inter actions in sha ping gut micr o-biome composition (Wexler et al. 2016, Verster et al. 2017 ).Andy then presented ongoing studies aimed at dissecting the mechanism and impact of specific antibacterial toxins produced by commensal microbes during health and disease .T hese experiments combine gnotobiotics, synthetic biology (Lim et al. 2017 ), bioc hemical, and structur al a ppr oac hes to understand the mechanisms of interbacterial antagonism in the gut microbiome.

Deciphering the immune system of bacteria
Rotem Sorek (Weizmann Institute , Reho vot, Israel) presented data on mechanisms of bacterial defence against phages.He sho w ed how such systems can be identified by systematic analysis of av ailable micr obial genomes, an a ppr oac h that r ecentl y led to the discovery of many dozens of new defence systems (Doron et al. 2018 ).These anal yses curr entl y tr ansform our understanding of bacterial immunity, and surprisingly show that k e y components of the human innate immune system evolved from bacterial defence against phages (Wein and Sorek 2022 ).Sorek sho w ed ho w studying bacterial immune system can r e v eal ne w concepts in animal and plant innate immunity (Rousset et al. 2023 ).

What to do when CRISPR fails? Back-up plans for phage defence
Jose ph Bond y-Denom y (Uni v ersity of California San Fr ancisco, USA) described how bacteriophages antagonize the c yclicoligonucleotide b ased a ntiphage s ignaling s ystem (CBASS) using an anti-CBASS protein (Acb2).Acb2 sequesters or 'sponges' up the signaling nucleotides that cyclase enzymes generate in response to phage infection (Huiting et al. 2023 ).Acb2 acts as a hexamer, whic h gener ates thr ee cyclic dinucleotide (CDN) binding sites.Acb2 is encoded by man y pha ges and pr opha ges acr oss Gr amnegative bacteria and recent work has revealed a second binding site that is distal from the CDN binding site, which binds with high affinity to cAAA and cAAG CBASS signalling trinucleotides (Cao et al. 2024 ).Together, the ∼90 amino acid Acb2 protein likely inactiv ates nearl y all CBASS systems.

Inhibition of virion assembly in antiviral defence
Karen Maxwell (University of T oronto, T oronto, Canada) described a new antiphage defence system encoded by a Pseudomonas aeruginosa pr opha ge .This pr otein inhibits virion assembl y of superinfecting pha ges thr ough an inter action with the ta pe measur e pr otein, a critical component of long-tailed pha ges.Pr opha ges that have this defence encode a counter-defence protein that is expressed during the lytic cycle that allows them to e v ade the assembly inhibition.As prophage survival depends on survival of the bacterial host, they fr equentl y encode defence systems to protect the cell in which they reside (Bond y-Denom y et al. 2016 , Rocha and Bikard 2022 , Patel and Maxwell 2023 ); understanding these defences and how they protect their bacterial host will provide critical insight into the phage-host evolutionary arms race.

Enormous diversity of antir etr on pr oteins in phages
Nassos Typas (EMBL Heidelber g, German y) first discussed that Restriction-modification systems and CRISPR, tools that have propelled genetic engineering, are systems that bacteria use to defend pha ge.Yet, onl y r ecentl y hav e we started to understand the multitude of systems bacterial employ in this warfare.Among them, bacterial r etr ons, containing the first pr okaryotic r e v erse tr anscriptases discov er ed, wer e r ecentl y shown to act as phage defence systems (Gao et al. 2020, Millman et al. 2020, Bobonis et al. 2022 ).To explore on possible ways phages use to bypass retrons, Nassos Typas presented a screen his lab performed, using metagenomic pha ge DNA libr aries fr om div erse envir onments, to identify proteins that inhibit the effector of one such retron, Retron-Sen2.T his wa y, they identified dozens of small pha ge pr oteins that bloc k the effector toxicity.The majority shared no obvious sequence homology with known systems or between each other, and many inhibited div er gent r etr ons, also during pha ge infection.By combining genetics, biochemistry, and structure prediction, he presented e vidence of conv er gent e v olution in the w ay bloc kers counter act the defence system.

Molecular secrets of seventh pandemic Vibrio cholerae
Melanie Blokesch (EPFL, Switzerland) presented new findings on the defence mechanisms of Vibrio cholerae .Her focus was on the specific strains responsible for the ongoing seventh cholera pandemic, also recognized as the seventh pandemic O1 El Tor (7PET) clade (Mutreja et al. 2011 ).Within this lineage, recent research has highlighted several defence systems primarily encoded within long-known but pr e viousl y understudied pathogenicity islands/mobile genetic elements (Dziejman et al. 2002 ).These systems include two DNA defence modules (Ddm), which play a critical role in safeguarding V. cholerae from phages and/or plasmids (Jaskólska et al. 2022 ).Further investigations are needed to comprehend how these newfound defence systems contribute to the success of the 7PET clade of V. cholerae .

Dynamics of the peptidoglycan synthesis machinery during Staph ylococcus aur eus cell division
Mariana G. Pinho (ITQB, Univ ersidade Nov a de Lisboa) explored FtsZ tr eadmilling's r ole in bacterial cell wall synthesis and division, focusing on Staphylococcus aureus , a deadly antibioticr esistant pathogen.FtsZ tr eadmilling involv es asymmetric FtsZ filament polymerization at the plus end and depolymerization at the minus end, causing FtsZ polymer movement around the division site.Mariana sho w ed that FtsZ treadmilling is crucial only during early cytokinesis stages but becomes dispensable afterw ar ds (Monteiro et al. 2018 ).Initial hypotheses suggested its role in pr omoting dir ectional mov ement of se ptal pe ptidoglycan synthases around the division site (Bisson-Filho et al. 2017, Yang et al. 2017 ).Ho w e v er, single molecule tr ac king micr oscop y sho w ed that velocity of FtsW/PBP1, staphylococcal essential septal peptidogl ycan synthases, r emains unaffected upon FtsZ tr eadmilling inhibition.In contr ast, peptidogl ycan synthesis inhibition significantl y hinder ed septum constriction and FtsW/PBP1 mov ement (Sc häper et al. 2023 ), emphasizing peptidoglycan synthesis' critical role in driving cytokinesis.c heric hia coli.With the support of single-cell quantitative imaging data acr oss v arious nutrient conditions, she expanded on a recent study from her group on chromosome folding (Xiang et al. 2021 ) to suggest that excluded volume effects involved in chromosome compaction also result in effective displacement forces that contribute to the demixing and segregation of sister chromosomes.

Novel effector proteins of the S. aureus Type VII secretion system
Tr acy P almer (Biosciences Institute, Ne wcastlle Univ ersity, Ne wcastle, England) discussed targeting of antibacterial toxins to the type VII secretion system in S. aureus (Cao et al. 2016 ).She presented data showing that three small helical proteins, EsxB, EsxC, and EsxD are required for export of the EsaD n uclease to xin (Yang et al. 2023 ).These proteins bind to EsaD's N-terminal LXG-like do-main resulting in formation of a long helical stalk structure.She also described TslA, the first example of a T7SS toxin with a reverse domain arrangement (Garrett et al. 2023 ).Biochemical evidence was presented demonstrating that it has phospholipase activity and that it is toxic to bacteria lacking TilA immunity proteins.

Mechanical interplay of the OM (outer membrane) and the peptidoglycan layer in Gram-negative bacteria: a key to resisting turgor pr essur e and cell bursting
Jean-Fr ançois Collet (UC Louv ain, Belgium) in his pr esentation, first r e visited the understanding of how Gr am-negativ e bacteria handle osmotic c hallenges.Tr aditionall y, it was belie v ed that peptidogl ycan pr ovided the mec hanical support to r esist incr eased tur gor pr essur e during hypoosmotic str ess (Egan et al. 2020 ).How- e v er, Collet pr esented a combination of genetics, single-cell fluor escence micr oscopy, and bioc hemistry data that c hallenged this notion.He highlighted that while peptidoglycan is essential, it is not sufficient for survival under osmotic stress.Collet proposed that attac hing peptidogl ycan to the outer membr ane forms a mechanical unit that allows periplasmic pressure buildup, thus balancing tur gor pr essur e acr oss the inner membr ane and pr e v enting cell lysis (Asmar et al. 2017, Deghelt et al. 2023 ).

Intramitochondrial localization of Midichloria bacteria: wher e , when and how
Davide Sassera (University of Pavia, Italy) described advances in r esearc h on Midic hloria , a genus of tic k-borne m utualist bacteria, found to reside within the intermembrane space of different tick species (Stavru et al. 2020 ).Advanced 2D and 3D electron microscopy suggested that Midichloria bacteria influence mitochondrial network fr a gmentation (Uzum et al. 2023 ).Additionally, com-par ativ e genomics r e v ealed a possible connection between the bacterium's ability to colonize mitochondria and the presence of specific genetic traits, including type IV secretion system and flagellum (Floriano et al. 2023 ).Curr ent anal yses ar e focused on inv estigating pr otein-pr otein inter actions between Midic hloria and the tick, looking for the molecular mechanisms at the basis of this unique symbiosis.

T he c ytosolic LPS-sensing noncanonical inflammasome pathway in bacterial infection
Feng Shao (National Institute of Biological Sciences, Beijing) reported the latest de v elopment about the cytosolic LPS-sensing caspase-11/4 noncanonical inflammasome.He described in detail how caspase-11/4 recognize LPS and becomes activated (Shi et al. 2014 ).The activated caspases, specifically the p20/p10 au-   toprocessed form, use an exosite to recognize Gasdermin D (GS-DMD) C-terminal domain, rendering a tetrape ptide-inde pendent cleav a ge to liber ate the por e-forming domain of GSDMD (Wang et al. 2020 ).He sho w ed that this substr ate-r ecognition mec hanism also applies to caspase-1.His talk mainly covered a new finding that LPS-activated caspase-4 but not caspase-11 efficiently processes pro-IL-18 for maturation, linking infection-induced pyroptosis to antibacterial ada ptiv e imm unity (Shi et al. 2023 ).Structur all y, caspase-4 uses the same exosite to recruit pro-IL-18.Lastly, he discussed how S. flexneri employs its T3SS effectors (IpaH9.8,OspC3, and IpaH7.8) to block the noncanonical inflammasome at different steps, highlighting its crucial function in antibacterial defences.

Legionella and the host epitranscriptome
Elizabeth Hartland (Hudson Institute of Medical Research, Australia) described how the intracellular bacterial pathogen Legionella pneumophila caused the post-transcriptional decay of host mRNA encoding gl ycol ytic enzymes, ther eby r educing the glycolytic activity of infected host cells.Studies of genome deletion mutants (Wibawa et al. 2022 ) revealed a single Dot/Icm effector pr otein that dr ov e host mRNA degr adation.Using iCLIP2 pr otocols, the bacterial effector was shown to be a new kind of host mRNA binding protein that recognized a guanine rich motif in target mRNAs (McCaffrey et al., unpublished work).This raises the possibility that L. pneumophila and other pathogens dir ectl y tar get the host epitranscriptome during infection.

Pathogen phage cooperation during mammalian infection
Anat Herskovits (Tel Avi v Uni v ersity, Isr ael) r eported a r emarkable ada ptation of pr opha ges to their pathogenic host.Pr opha ges that inhabit pathogenic bacteria adapt their responses and regulatory machineries to support the survival of their hosts in the mammalian en vironment.T he intracellular bacterial pathogen Listeria monocytogenes strain 10403S carries two phage elements in its genome, one is an active prophage producing virions, whereas the other defectiv e pr oducing tailocins (Argov et al. 2019 ).The Figur e 12. T he organizers relaxing on the last day after concluding that the conference had gone well.Lead organizer Birgitta Henriques-Normark for the next Interacademy conference to be held in Sweden pictured on the right.two elements hold the capacity to trigger cell lysis upon stress, and yet during Lm infection of macr opha ge cells their response is coordinated and further adapted to avoid the production of virion/tailocin particles and cell lysis .T he two elements are coregulated by the same antir epr essor, encoded by the tailocin element, which triggers their induction both under stress conditions and in the mammalian niche (Argov et al. 2019 ).In the mammalian environment the two elements do not proceed into lytic production, yet instead conjointly mediate the excision of the prophage from the bacterial comK gene, a gene that was pr e viousl y shown to promote Lm 's intracellular growth (Rabinovich et al. 2012, Pasechnek et al. 2020 ).Anat further demonstrated that the pr opha ge has acquired a specific adaptation that attenuates its induction in the mammalian envir onment, ther eby supporting Lm 's surviv al and gr owth.The pr esented data support the premise that pr opha ges that associate with bacterial pathogens have evolved to align their response with the pathogenic lifestyle of their host, being pathoadapted to the mammalian environment.

Uncovering mechanisms of pneumococcal-host interactions with synthetic gene r egulator y networks
Jan-Willem Veening (University of Lausanne, Switzerland) introduced phenotypic v ariation, wher e clonal bacteria exhibit different traits under identical conditions (Smits et al. 2006 ).This phenomenon, widespread yet poorly understood, was explored using synthetic biology and the pneumococcal capsule as an example.Veening likened pneumococcus to a cloaked Klingon Bird of Prey, hidden from scanners (or the host immune system) due to its capsule.Decloaking (losing the capsule) allows it to attack, akin to the Bird of Prey firing its phasers (and pneumococcus attaching to epithelial cells).Using CRISPRi-based synthetic gene regulatory networks, ca psule pr oduction was uncoupled fr om its natur al expr ession.This demonstrated that strains with oscillatory capsule production were more adept at colonizing mice than homogeneously expr essing bacteria, pr oving the significance of gene expr ession heterogeneity during infection (Rueff et al. 2023 ).

Shaping Yersinia virulence for acute and persistent infections
Petr a Dersc h (Univ ersity Münster, German y) r eported how the enteropathogenic pathogen Yersinia pseudotuberculosis is able to cause persistent infections.Using an oral mouse infection model, it was shown that the loss of the cytotoxic necrotizing factor (CNF Y ), whic h activ ates Rho GTP ases (Chaopr asid and Dersc h 2021 ) and triggers the induction of acute inflammatory responses and tissue destruction, is sufficient to trigger a switch from acute into persistent infection (Heine et al. 2018, Chaoprasid et al. 2021 ).During infection, CNF Y is important for the initial entry into lymphatic tissues and later for the inactivation of neutrophils, indicating that delayed colonization and a reduction of neutrophil death are crucial for the development of Yersinia persistence.

Inflammation as a driver of Mycobacterium tuberculosis pathogenesis
Christina Stallings (Washington University School of Medicine, USA) discussed the effects of inflammation on Mycobacterium tuberculosis pathogenesis.In particular, neutrophil recruitment and accumulation in the lungs is associated with tuberculosis dis-ease pr ogr ession, ho w e v er, whether the neutr ophils activ el y affect M. tuberculosis pathogenesis w as unkno wn.Using genetic mouse models of M. tuberculosis infection, it was shown that neutr ophils activ el y pr omote M. tuberculosis r eplication and pathogenesis (Kimmey et al. 2015 ).In response to M. tuberculosis infection, type I interferon is induced in neutr ophils, whic h pr omotes the r elease of neutr ophils extr acellular tr a ps (NETs).NETs contribute to increased pathogen replication (Sur Chowdhury et al. 2022 ), where inhibition of NETosis leads to better control of M. tuberculosis pathogenesis .Furthermore , the autophagy-associated protein ATG5 was identified as a critical regulator of type I interferoninduced NETosis during M. tuberculosis infection (Kinsella et al. 2023 ), r e v ealing ne w potential tar gets for modulating neutrophil behaviour during M. tuberculosis infection to better control infection.

Meet-the-editor session and panel discussion with international guests
The scientific pr ogr amme was complemented by two additional items on the agenda.First, an editor session (Fig. 8 ) chaired by Anke Sparmann, a former editor no w w orking as a scientific writer at the Helmholtz Institute for RNA-Based Infection Researc h Würzbur g.She hosted Nonia P ariente, editor-in-c hief of PLoS Biolog y ; Carmen Buc hrieser, one of the two editors-in-chief of microLife , the journal of the European Academy of Microbiology (EAM); and Jessica Thompson, who had just joined the editorial team of Nature Microbiology .It was an exceptionally wellattended and liv el y session, notwithstanding the fact that it partly ov erla pped with the lunch break on T hursda y.Second, Jörg Vogel and Carmen Buchrieser chaired a panel discussion focused on 'The importance of microbiology and infectious disease r esearc h in the year 2023' (Fig. 9 ).The three invited participants included Elior a Ron, EAM Secr etary Gener al, and pr ofessor of micr obiology in Isr ael, whic h is another country with a v ery str ong micr obiology pr ogr amme, as w ell as Sey ed E. Hasnain and Feng Shao, who hail from and work in India and China, r espectiv el y.The latter two countries together r epr esent almost a third of the world's population, but it was interesting to learn about their efforts to de v elop a structur ed a ppr oac h to pr omoting micr obiology as a strong discipline in its own right.

Summary and outlook
These three September days will doubtlessly be remembered for the excellent talks and a general feeling of excitement shared by the organizers , speakers , and attendees of Microbiology 2023.T he atrium of the IMIB was buzzing with conversations and scientific discussions during the light dinner and poster session on Wednesday night (Fig. 10 ).As e v er, the Staatlic her Hofkeller, located in the cellars under the Würzburger Residence (a world heritage place), pr ovided a gr eat v enue for the conference dinner on T hursda y night (Fig. 11 ).Almost 900 years of history make this place one the oldest wineries in the world.
The or ganizers ar e indebted to a great local organization team, which included Hilde Merkert, Monika Sc hr aut, and Mona Alzheimer from the IMIB and Stefanie Ziegler, Tobias Kerrinnes, Britta Grigull, Tim Sc hn yder, and Luisa Mac har o wsk y from the Würzburg Helmholtz Institute .T hanks to them, the conference went very smoothly and nobody got lost despite the fact that by pure coincidence, the conference venue happened to be surrounded by no fewer than five construction sites in September 2023.These sites included a deep construction pit for the new Helmholtz Institute building right opposite the IMIB .W e would also like to ac knowledge gener ous financial support by the Leopoldina, the Alfried Krupp von Bohlen und Halbach-Stiftung as well as intr am ur al funds of the Helmholtz Institute for RNAbased Infection Research.
As Microbiology 2023 ended on Friday afternoon, there was great enthusiasm for the idea of k ee ping this successful conference format, with the aim to come together and put the spotlight on the latest de v elopments and emerging new concepts in the quest to fathom the intricate lifestyles and molecular compositions of microbes.In this regard, the present organizers were glad to learn that the Swedish national academy, will take the lead in planning the next suc h Inter academy confer ence in 2026.While the venue in Sweden is yet to be a gr eed upon, Bir gitta Henriques Normark will serve as the lead organizer (Fig. 12 ).As a professor of Clinical Microbiology at the Karolinska Institute and the head physician of the associated University Hospital, Henriques Normark is a well-established name in European microbiology.Moreo ver, ha ving recently been elected President of the Ro y al Sw edish Academy of Sciences, she has a natural interest in partnering with other national academies to serve what is one of the main purposes of these institutions: to nurture a community of scientifically like-minded people and highlight the latest de v elopments in science.

Figur e 1 .
Figur e 1. T he organizers David Holden, Jörg Vogel, Pascale Cossart, Jörg Hacker, and Staffan Normark (from left to right) work-lunching in Berlin in April 2019 and having a first go at planning what back then was meant to be Microbiology 2020 and because of the COVID-19 pandemic turned out to be Microbiology 2023.

Figure 2 .
Figure 2. Jör g Hac ker, past pr esident of the German National Academy of Sciences (2010-2020) and founding dir ector of the Institute for Molecular Infection Biology of the University of Würzburg (1993-2008).

Figure 3 .
Figure 3. Inside the building of the Institute for Molecular Infection Biology.

Susan Bullman (
Fred Hutchinson Cancer Center, Seatle, WA, USA) discussed how the tumor micr oenvir onment (TME), consisting of F igure 4. F rom left to right the speakers of the 'Infection biology and microbiome' session Andrew Goodmann and Sophie Helaine as well as session chairs Thomas Rudel and Jörg Vogel.The two other speakers, not pictured here, were Susan Bullman and Andreas Bäumler.a complex network of malignant and nonmalignant cells, significantly impacts tumour behaviour.Molecular analyses have rev ealed an intr atumour al micr obiota within human solid cancers, yet understanding their interactions with human tumour components and contributions to disease pr ogr ession is limited (Bullman 2023 ).Recent findings from the Bullman's lab uncover how intr atumour al bacterial communities contribute to cancer progression in oral and colorectal cancers (Galeano Niño et al. 2022 ).Using spatial transcriptomics, spatial proteomics, and single-cell sequencing (INVADEseq; Galeano Niño et al. 2023 ), the r esearc h r e v eals intr atumour al bacteria localize to imm unosuppr essiv e tumour regions and infect cancer epithelial cells, upregulating cancer-related pathwa ys .T hese insights offer promise for targeted ther a pies disrupting bacterial-human inter actions in the TME.

F
igure 5. F rom left to right the speakers of the 'Phage biology and defence' session Nassos Typas, Melanie Blok esch, Jose ph Bond y-Denom y, Karen Maxwell, and Rotem Sorek, as well session chair Pascale Cossart.The other chair, Chase Beisel, is not in the picture.
Christine Jacobs-Wagner (Howard Hughes Medical Institute, Stanfor d University, Stanfor d, USA) presented unpublished w ork that addressed the long-standing mystery surrounding the mechanism of c hr omosome segr egation in the model bacterium Es-F igure 6. F rom left to right the speakers of the 'Molecular biology and bacterial cell biology' session Christine J acobs-Wagner, Trac y Palmer, Mariana G. Pinho, Davide Sassera, and Jean-François Collet (second to the right).Session c hairs wer e Fr anz Narberhaus (third to the right) and Cynthia Sharma (to the right).

F igure 7 .
F rom left to right the speakers or session chairs of the 'Molecular infection biology' session Feng Shao, David Holden (c hair), Petr a Dersc h, Birgitta Henriques Normark (chair), Jan-Willem Veening, Christina Stallings, and Elizabeth Hartland.Further speaker Anat Herskovits is not in the picture.

F
igure 8. F rom left to right are the panelists of the 'Meet-the-editor' session Anke Sparmann (session chair, HIRI Würzburg), Carmen Buchrieser ( microLife ), Nonia Pariente ( PLoS Biology ), and Jessica Thompson ( Nature Microbiology ).F igure 9. F rom left to right are the panelists of 'The importance of microbiology and infectious disease research in the year 2023' session, starting with c hairs Jör g Vogel and Carmen Buc hrieser, and participants Elior a Ron (Isr ael), Seyed E. Hasnain (India), and Feng Shao (China).

Figur e 10 .
Figur e 10.P oster session on Wednesday night.

Figure 11 .
Figure 11.Impr essions fr om the confer ence dinner at the Staatlic her Hofkeller, located under the Würzburger Residence (a world heritage place), on T hursda y night.