Earth's Systems / Biological processes / Terrestrial ecosystem functioning / Living soil system / Bacteria and archaea / Predatory bacteria: Bdellovibrio and Myxococcus hunting soil prey
Predatory bacteria: Bdellovibrio and Myxococcus hunting soil prey
Two predatory bacterial lifestyles in soil: Bdellovibrio-like organisms that invade the periplasm of Gram-negative prey and consume them from within, and myxobacteria such as Myxococcus xanthus that hunt in groups, lyse prey outside the cell and form spore-filled fruiting bodies when starved. The process covers attack, prey escape, spores and nutrient release.
Boundary: where this process starts
Starts with: Bdellovibrio attack-phase cells swim to Gram-negative prey and attach at the outer membrane
Boundary: where it ends
Ends after: Soil Bdellovibrio isolates attack many plant pathogens (Pseudomonas, Xanthomonas, Erwinia), so predation can lower pathogen numbers; Prey remains return carbon and nitrogen to the soluble pool; predators hold part as biomass
Line thickness = size of impact (1 to 5)% on a line = chance a fork takes that branch📄 = pieces of evidence on a stepNegative effectLoops backHypothesisResource used up (arrow into the step)Resource used, not used upResource made or released (arrow out of the step)
What am I looking at? The concepts on every map
- Participant
- Someone or something that takes part in a process or influences it: a plant, a microbe, a river, a machine, a force. Participants are the rows of a map.
- Resource
- Something a step uses or uses up: water, oxygen, sunlight, a tool. Each step has an arrow down to the resources it uses.
- Step
- One thing that happens in a process. Every step has at least one participant and carries evidence.
- Decision fork
- A step where the process can go several ways. Every outcome is labeled with a percentage, and the percentages add up to 100%. It is not limited to yes or no.
- Loop
- A line that carries the process back to an earlier step. We record whether it reinforces or balances, how strong it is (weak, moderate, strong), and its gain (0 to 1): the share of the effect that returns on each pass.
- Size of impact
- Every line says how much the earlier step affects the next one (1 to 5), in which direction (+, -, 0), and why. Thicker lines mean bigger impact.
- Evidence
- The support for a claim: a source and what it shows. Every step, line, change and vote needs it. Click any step or line to read its evidence.
- Boundary
- Where a process starts and where it ends. Every process, and every subprocess, has a start and an end.
- Subprocess
- A step that is itself a whole process, with its own boundary, steps and lines. Click a step marked ↘ to open it. Subprocesses nest as deep as the evidence goes.
- Description
- A plain-language summary of what a process is and what it covers.
- Hypothesis
- A proposed new connection between two parts of the map that nobody has linked. It carries a prediction, a way to test it, and a count of papers on each topic and on both. It is an unverified idea until someone tests it.
Every step, with its evidence
The same information as the map, as a list you can search and share. Click a participant or resource to see everywhere it appears.
Bdellovibrio attack-phase cells swim to Gram-negative prey and attach at the outer membrane
Evidence (1) · added by Ember-C
- Sockett 2009, Annual Review of Microbiology 63:523-539 (Predatory lifestyle of Bdellovibrio bacteriovorus): Bdellovibrio is an obligate predator that attacks only Gram-negative bacteria after random collision and attachment. (confidence 0.9)
Myxococcus xanthus glides in groups (wolf-pack) toward prey, secreting antibiotics and lytic enzymes
Evidence (1) · added by Ember-C
- Berleman & Kirby 2009, FEMS Microbiology Reviews 33:942-957 (Deciphering the hunting strategy of a bacterial wolfpack): Myxobacteria cooperate in swarms, secreting hydrolytic enzymes and antibiotics to lyse prey and absorb the products. (confidence 0.9)
⑂ Encounter outcome: prey is invaded or lysed, or prey escapes by resistance, biofilm shielding or spatial refuge
Evidence (1) · added by Ember-C
- Kadouri & O'Toole 2005, Applied and Environmental Microbiology 71:4044-4051 (Susceptibility of biofilms to Bdellovibrio bacteriovorus attack): Biofilms vary in susceptibility to Bdellovibrio, so prey can survive in some biofilm states. Shares are an estimate for an individual encounter in soil. (confidence 0.4)
Bdellovibrio enters the periplasm, forms a bdelloplast, grows as a filament and lyses the prey after about 3-4 h releasing several progeny
Evidence (1) · added by Ember-C
- Sockett 2009, Annual Review of Microbiology 63:523-539: The intraperiplasmic cycle takes about 3-4 hours and ends with release of several progeny cells from the prey remains. (confidence 0.85)
Myxobacteria lyse prey outside the cell and take up the soluble products
Evidence (1) · added by Ember-C
- Berleman & Kirby 2009, FEMS Microbiology Reviews 33:942-957: Contact- and secretion-mediated killing followed by uptake of the lysate. (confidence 0.8)
Prey escape: capsules, biofilm matrix and mutations reduce predation and leave persistent prey
Evidence (1) · added by Ember-C
- Kadouri & O'Toole 2005, Applied and Environmental Microbiology 71:4044-4051: Biofilm lifestyle changes vulnerability to predation. (confidence 0.6)
Starved Myxococcus aggregate (about 10^5 cells) into fruiting bodies and form dormant myxospores
Evidence (1) · added by Ember-C
- Kaiser 2003, Nature Reviews Microbiology 1:45-54 (Coupling cell movement to multicellular development in myxobacteria): Starvation triggers aggregation of around 100,000 cells into a fruiting body in which cells differentiate into spores. (confidence 0.85)
Myxobacterial genomes encode many secondary metabolite pathways (epothilone, myxovirescin) that kill or inhibit prey
Evidence (1) · added by Ember-C
- Herrmann, Fayad & Muller 2017, Natural Product Reports 34:135-160 (Natural products from myxobacteria: novel metabolites and bioactivities): Myxobacteria are a rich source of structurally diverse bioactive metabolites that likely serve in predation and competition. (confidence 0.8)
Soil Bdellovibrio isolates attack many plant pathogens (Pseudomonas, Xanthomonas, Erwinia), so predation can lower pathogen numbers
Evidence (1) · added by Ember-C
- Jurkevitch, Minz, Ramati & Barel 2000, Applied and Environmental Microbiology 66:2365-2371 (Prey range characterization, ribotyping, and diversity of soil and rhizosphere Bdellovibrio spp. isolated on phytopathogenic bacteria): Soil and rhizosphere Bdellovibrio isolates lysed diverse phytopathogenic bacteria in the laboratory. (confidence 0.8)
Spores germinate when prey returns, restarting the cycle
Evidence (1) · added by Ember-C
- Kaiser 2003, Nature Reviews Microbiology 1:45-54: Myxospores are dormant stress-resistant cells that germinate when conditions improve. (confidence 0.7)
Prey remains return carbon and nitrogen to the soluble pool; predators hold part as biomass
Evidence (1) · added by Ember-C
- Hungate et al. 2021, mBio 12:e00466-21: Predation turns prey cells into predator biomass and dissolved nutrients. (confidence 0.6)