Bacteria
Bacteria are the original lean startups—organisms stripped to the minimum viable components that can reproduce. No nucleus, no organelles, no complexity that doesn't directly serve replication. A bacterium divides every 20 minutes under optimal conditions, meaning one cell becomes a billion in 10 hours. This isn't just fast—it's fast enough to evolve visibly within human lifetimes. The strategic implications are profound. Bacteria don't plan; they iterate. Antibiotic resistance doesn't require intelligence—it requires enough random variation that some individuals survive, combined with fast enough reproduction that survivors dominate within days. The bacterial strategy is brute-force search: generate millions of variants, let the environment select winners, repeat. It's evolution as algorithm. Bacteria also invented horizontal gene transfer—sharing genetic information between unrelated individuals. This is open-source biology: innovations spread laterally across species, not just vertically through generations. A resistance gene that evolves in one bacterium can transfer to completely different species. The bacterial commons accelerates adaptation beyond what any single lineage could achieve. The business parallels are uncomfortable. Bacteria succeed through strategies that would horrify corporate strategists: no planning, no differentiation, no competitive moat. Just speed, variation, and ruthless selection. Yet bacterial 'companies' have dominated Earth for 3.5 billion years while every sophisticated competitor has gone extinct multiple times. When exploring bacteria in this section, look for: iteration speed (how does fast reproduction substitute for planning?), horizontal transfer (how does information sharing accelerate adaptation?), and minimal viable organisms (what can you strip away and still succeed?).
Acinetobacter baumannii
Acinetobacter baumannii earned the nickname 'Iraqibacter' during the Iraq War, when it caused devastating wound infections in military personnel. But...
Actinoplanes
Actinoplanes species produce acarbose, an alpha-glucosidase inhibitor used to treat type 2 diabetes. This compound slows carbohydrate digestion, reduc...
Aeromonas salmonicida
Aeromonas salmonicida causes furunculosis, a devastating disease of salmon and trout aquaculture. Like Vibrio species, A. salmonicida uses quorum sens...
Agrobacterium tumefaciens
Agrobacterium tumefaciens performs what may be nature's most audacious act of horizontal gene transfer: it inserts its own DNA into plant chromosomes,...
Aliivibrio logei
Aliivibrio logei represents the cold-water counterpart to Vibrio fischeri's temperate lifestyle. Both bacteria form bioluminescent symbioses with squi...
Amycolatopsis rifamycinica
Amycolatopsis rifamycinica produces rifamycins, antibiotics that became pillars of tuberculosis treatment alongside streptomycin and isoniazid. The di...
Anabaena
Anabaena demonstrates that bacteria can evolve multicellular organization with division of labor. This filamentous cyanobacterium grows as chains of c...
Antibiotic-Producing Bacteria
Leafcutter ants carry pharmaceutical factories on their bodies. Pseudonocardia bacteria grow in specialized structures on ant cuticles, producing anti...
Azoarcus sp. BH72
Azoarcus sp. BH72 was isolated from Kallar grass in Pakistan, a salt-tolerant plant growing in saline soils without fertilizer. The bacterium colonize...
Azospirillum brasilense
Azospirillum brasilense represents a different model of plant-microbe mutualism than nodule-forming rhizobia. Rather than forming specialized structur...
Azotobacter
Azotobacter are free-living soil bacteria capable of fixing atmospheric nitrogen without requiring plant symbiosis. They possess the nitrogenase enzym...
Azotobacter vinelandii
Azotobacter vinelandii fixes nitrogen without any plant partner—a remarkable feat given that nitrogen fixation requires protection from oxygen, which...
Bacillus subtilis
Bacillus subtilis has evolved one of nature's most elegant systems for genetic adaptation: natural competence. Unlike E. coli, which primarily receive...
Bdellovibrio bacteriovorus
Bdellovibrio bacteriovorus is a bacterial shark—a tiny, fast-swimming predator that hunts, kills, and consumes other bacteria. Unlike myxobacteria's c...
Bradyrhizobium japonicum
Bradyrhizobium japonicum forms the foundational partnership underlying global soybean production. This slow-growing bacterium—hence 'brady' meaning sl...
Buchnera
Buchnera are endosymbiotic bacteria living within aphid cells that synthesize amino acids aphids cannot produce from plant sap. They are transmitted v...
Burkholderia cepacia
Burkholderia cepacia complex represents a group of closely related species that have become notorious in cystic fibrosis care. Like Pseudomonas aerugi...
Chondromyces crocatus
Chondromyces crocatus builds fruiting bodies that challenge our understanding of bacterial capabilities. These structures reach 1 millimeter in height...
Chromobacterium violaceum
Chromobacterium violaceum has become a workhorse for quorum sensing research precisely because its communication system produces a visible output: vio...
Chroococcidiopsis
Chroococcidiopsis defines the boundary between life and lifelessness. This cyanobacterium survives conditions that kill everything else: the hyperarid...
Cryptoendolithic Organisms
Cryptoendolithic organisms live inside rocks in Antarctica's dry valleys—one of Earth's most Mars-like environments. Temperatures average -20°C, liqui...
Cupriavidus taiwanensis
Cupriavidus taiwanensis shatters assumptions about which bacteria can form nitrogen-fixing symbioses. This member of the Burkholderiaceae—a family not...
Cyanobacteria
Cyanobacteria are the reason you're reading this. 2.4 billion years ago, these photosynthetic bacteria evolved a new trick: splitting water molecules...
Cyanobacterial Akinetes
Akinetes are thick-walled dormant cells produced by cyanobacteria when conditions deteriorate. These survival structures can persist for centuries—via...
Cystobacter fuscus
Cystobacter fuscus demonstrates how cell adhesion shapes collective behavior in predatory bacteria. Unlike some myxobacteria where cells maintain loos...
Cytophaga hutchinsonii
Cytophaga hutchinsonii glides across surfaces faster than any other bacterium—up to 15 micrometers per second. This remarkable motility, combined with...
Deinococcus radiodurans
Deinococcus radiodurans—nicknamed 'Conan the Bacterium'—can survive radiation doses 1,000 times higher than would kill a human. Its genome gets shatte...
Enterococcus faecalis
Enterococcus faecalis has refined horizontal gene transfer into something approaching a marketplace. While E. coli exchanges genes somewhat randomly t...
Escherichia coli
E. coli serves as the chapter's primary biological example, demonstrating how a single-celled organism with no brain or nervous system makes better re...
Frankia
Frankia represents an entirely independent evolution of plant-microbe nitrogen fixation. While Rhizobium and its relatives partner with legumes, Frank...
Fusobacterium nucleatum
Fusobacterium nucleatum serves as the great connector of oral biofilm ecology. This spindle-shaped bacterium possesses surface adhesins that bind to b...
Gloeocapsa
Gloeocapsa blackens rocks worldwide—from tropical monuments to arctic cliffs. This cyanobacterium produces dark pigments protecting against UV radiati...
Gluconacetobacter diazotrophicus
Gluconacetobacter diazotrophicus solved the puzzle of how Brazilian sugarcane thrives with minimal nitrogen fertilizer. This bacterium lives inside su...
Haemophilus influenzae
Haemophilus influenzae holds a unique place in biological history: it was the first free-living organism to have its complete genome sequenced, in 199...
Helicobacter pylori
Helicobacter pylori has made a permanent home in one of the most hostile environments imaginable: the human stomach. To survive in an acid bath that k...
Herbaspirillum seropedicae
Herbaspirillum seropedicae colonizes grasses promiscuously, forming endophytic associations with rice, maize, sorghum, and sugarcane. Unlike Rhizobium...
Kitasatospora
Kitasatospora was originally classified within Streptomyces but proved distinct enough for separate genus status. This taxonomic separation correlated...
Klebsiella pneumoniae
Klebsiella pneumoniae has become the poster child for antibiotic resistance acquisition, demonstrating how horizontal gene transfer can outpace human...
Legionella pneumophila
Legionella pneumophila caused panic when it first emerged in 1976, killing 29 American Legion convention attendees in Philadelphia. The culprit proved...
Lysobacter enzymogenes
Lysobacter enzymogenes represents a predatory strategy intermediate between myxobacterial swarming and Bdellovibrio's individual hunting. This gliding...
Mesorhizobium loti
Mesorhizobium loti partners with Lotus japonicus, forming a model symbiosis that complements the Sinorhizobium-Medicago system. Where Medicago forms i...
Microcystis
Microcystis aeruginosa forms the toxic algal blooms that close beaches, contaminate drinking water, and kill livestock worldwide. This colonial cyanob...
Micromonospora
Micromonospora ranks second only to Streptomyces in the number of antibiotics discovered, including gentamicin and other aminoglycosides that remain c...
Mitochondria
Mitochondria are ancient bacterial invaders that became so essential you cannot imagine life without them. Between 1.5 and 2 billion years ago, an anc...
Myxobacteria
Myxobacteria are soil bacteria that use quorum sensing to coordinate multicellular development. When nutrients are depleted and population density is...
Myxococcus xanthus
Myxococcus xanthus has become the primary model for bacterial social behavior because it displays the full range of myxobacterial cooperative phenomen...
Neisseria gonorrhoeae
Neisseria gonorrhoeae has evolved perhaps the most sophisticated immune evasion system in the bacterial world: programmed antigenic variation. Rather...
Nitrobacter
Nitrobacter are nitrifying bacteria that complete the second step of nitrification, oxidizing nitrite (NO₂⁻) to nitrate (NO₃⁻). This produces the form...
Nitrosomonas
Nitrosomonas are nitrifying bacteria that oxidize ammonia (NH₄⁺) to nitrite (NO₂⁻), obtaining energy from this chemical transformation. They represent...
Nocardia
Nocardia species are known both as opportunistic pathogens and as sources of bioactive compounds. This dual identity—some species cause disease while...
Nostoc
Nostoc appears mysteriously after rains—gelatinous masses seeming to materialize from nowhere, leading to folk names like 'star jelly' and 'witch's bu...
Oscillatoria
Oscillatoria demonstrates that even bacteria without flagella can move with purpose. This filamentous cyanobacterium glides along surfaces through an...
Paenibacillus vortex
Paenibacillus vortex creates the most complex bacterial colony patterns known—intricate branching structures, rotating vortices, and fractal-like morp...
Photobacterium leiognathi
Photobacterium leiognathi demonstrates that the Vibrio fischeri-squid symbiosis has a parallel in fish. This bacterium colonizes the light organs of p...
Photobacterium phosphoreum
Photobacterium phosphoreum illuminates the ocean in ways Vibrio fischeri cannot. While V. fischeri achieves its spectacular bioluminescence through sy...
Photorhabdus luminescens
Photorhabdus luminescens brings bioluminescence to land through a remarkable three-way symbiosis. The bacterium lives mutualistically inside entomopat...
Porphyromonas gingivalis
Porphyromonas gingivalis has redefined our understanding of pathogenesis through its role as a 'keystone pathogen.' Despite comprising less than 0.01%...
Prochlorococcus
Prochlorococcus is the smallest known photosynthetic organism—a cyanobacterium streamlined to the absolute minimum needed for survival in the nutrient...
Proteus mirabilis
Proteus mirabilis creates some of the most striking patterns in microbiology: concentric rings of bacterial growth expanding across agar plates like r...
Pseudomonas aeruginosa
Pseudomonas aeruginosa doesn't attack immediately. At low population density in a wound or lung, it stays silent - producing no toxins, revealing no p...
Pseudomonas fluorescens
Pseudomonas fluorescens demonstrates that the same biofilm capabilities making P. aeruginosa a dangerous pathogen can serve beneficial purposes. This...
Rhizobia Bacteria
Rhizobia are nitrogen-fixing bacteria that form symbiotic relationships with legume plants. They convert atmospheric nitrogen (N₂) to ammonia, which p...
Rhizobium
Rhizobium bacteria convert atmospheric nitrogen into ammonia inside legume root nodules - a biochemical feat that plants cannot perform themselves. Th...
Rhizobium
Rhizobium bacteria form nodules on legume roots that perform a feat of chemistry no plant can manage alone: converting atmospheric nitrogen into ammon...
Saccharopolyspora erythraea
Saccharopolyspora erythraea produces erythromycin, a macrolide antibiotic that became essential for patients allergic to penicillin and for infections...
Salinispora tropica
Salinispora tropica rewrote assumptions about actinomycete ecology when it was discovered in 2005 as the first obligate marine actinomycete. Unlike te...
Salmonella
Salmonella demonstrates exponential growth at its extreme: under ideal conditions, populations can double every 20 minutes. This is among the fastest...
Salmonella typhimurium
Salmonella typhimurium represents one of nature's most sophisticated examples of adaptive gene acquisition under pressure. Like its close relative E....
Serratia marcescens
Serratia marcescens once performed miracles—or so medieval observers believed when communion bread mysteriously bled red. The 'blood' was actually pro...
Shewanella woodyi
Shewanella woodyi brings bioluminescence to the Shewanella genus, a group otherwise known for remarkable respiratory versatility rather than light pro...
Shigella flexneri
Shigella flexneri provides the clearest illustration of how horizontal gene transfer can transform an organism's ecological role. Genetically, Shigell...
Sinorhizobium meliloti
Sinorhizobium meliloti has become the model organism for understanding how nitrogen-fixing symbioses work at the molecular level. Its partnership with...
Sorangium cellulosum
Sorangium cellulosum holds the record for the largest bacterial genome—13 million base pairs, three times larger than E. coli. This genomic enormity i...
Spirulina
Spirulina (Arthrospira) transforms the cyanobacterial photosynthesis engine into human food. This filamentous cyanobacterium has been harvested as foo...
Staphylococcus aureus
Staphylococcus aureus represents one of humanity's most persistent bacterial adversaries, combining biofilm expertise with remarkable genetic adaptabi...
Stenotrophomonas maltophilia
Stenotrophomonas maltophilia represents the emerging challenge of intrinsically resistant organisms. Unlike bacteria that acquire resistance through h...
Stigmatella aurantiaca
Stigmatella aurantiaca produces the most elaborate fruiting bodies among myxobacteria—branching, tree-like structures that elevate spore-containing he...
Streptomyces coelicolor
Streptomyces coelicolor became the E. coli of actinomycete biology—the model organism whose deep genetic characterization illuminates the entire group...
Streptomyces griseus
Streptomyces griseus holds a unique place in medical history: it's the source of streptomycin, the first antibiotic effective against tuberculosis. Di...
Swarming Bacteria
Proteus mirabilis bacteria exhibit locust-like phase transitions at microscopic scale. At low density, cells swim independently through liquid. When s...
Synechococcus
Synechococcus complements Prochlorococcus in the ocean's photosynthetic workforce, dominating coastal and upwelling waters where Prochlorococcus strug...
Trichodesmium
Trichodesmium has mastered a trick that seemed impossible: fixing nitrogen in the oxygen-rich open ocean without specialized heterocyst cells. This co...
Vibrio cholerae
Vibrio cholerae reveals how environmental context shapes the strategy of horizontal gene transfer. In open water, this bacterium is relatively benign,...
Vibrio fischeri
Vibrio fischeri lives in two worlds. Free-swimming in the ocean at low density, it's invisible - producing no light. Colonizing a squid's light organ...
Vibrio harveyi
Vibrio harveyi has become the premier model for understanding complex quorum sensing because it uses not one but three parallel communication systems....
Vibrio parahaemolyticus
Vibrio parahaemolyticus shares quorum sensing machinery with V. fischeri but uses it for opposite purposes: causing seafood-borne illness rather than...
Vibrio vulnificus
Vibrio vulnificus represents the lethal extreme of the Vibrio genus that includes benign symbionts like V. fischeri. This bacterium causes the deadlie...