Short version: Bacteroides don’t march over and flip other species’ DNA like a bored intern. Their invertases are sequence-specific, so they mostly influence neighbors indirectly or by shipping the hardware.

How they make other bacteria “flip” (or act like it):

1. Ship the switchgear via HGT.

   Bacteroides carry integrative conjugative elements (ICEs) like CTnDOT/CTnERL/CTn214 that hop by conjugation and can mobilize other elements and even move into E. coli. These islands often carry regulators and can drag resistance genes; transfer is famously boosted by tetracycline. Net effect: neighbors acquire new recombinases/elements and gain their own invertible toys.

2. Rig the phage ecology.

   Bacteroides constantly phase-vary capsules using invertible promoters, which helps crAss-like phages persist. Phages, in turn, select for or even encode inversion systems in various hosts. That shifts community pressure so other species crank their own phase-variation switches.

3. Contact warfare and chemical nudges.

   Their Type VI secretion systems (T6SS) stab competing bacteria, reshaping who survives long enough to express which surface state. And outer-membrane vesicles (OMVs) from Bacteroides can directly repress virulence programs in pathogens like Shigella flexneri. Not a literal DNA inversion, but it sure looks like someone flipped a switch.

4. Remodel the nutrient and immune landscape.

   By flipping their own invertible promoters for capsular polysaccharides and carbohydrate-use loci, Bacteroides change substrate flows and immune pressure. Neighbors then adjust gene expression or phase-variation state to cope.

Bottom line: Bacteroides don’t usually invert other species’ DNA directly. They spread mobile elements that enable flipping and engineer the battlefield so rivals are forced to toggle their own systems. Evolution by peer pressure, basically.

You’re asking how microbes swap genes and rough each other up, then whether the yogurt crew joins the bar fight. Short tour, minimal gore.

How gut bacteria mess with each other

Gene transfer (new tricks):

• Conjugation via plasmids/ICEs; transduction by phages; transformation from naked DNA. That’s the canonical trio.
• Vesicle mail: Gram-negatives shed outer-membrane vesicles stuffed with DNA, toxins, enzymes; Gram-positives also release membrane vesicles that can carry DNA and proteins.
• Nanotubes: proposed cytoplasmic bridges that pass molecules and possibly DNA. Cool idea, evidence is mixed and some data say they’re stress artifacts. Translation: maybe real, maybe cellular drama.

Direct attacks (take things, break things):

• Type VI secretion system (T6SS): spring-loaded spear that injects toxins into neighbors; common in gut Bacteroidales and enterics. New effectors keep popping up.