Interspecies nutrient extraction and toxin delivery between bacteria

Abstract

Bacteria have developed various mechanisms by which they sense, interact, and kill other bacteria, in an attempt to outcompete one another and survive. Here we show that Bacillus subtilis can kill and prey on Bacillus megaterium. We find that Bacillus subtilis rapidly inhibits Bacillus megaterium growth by delivering the tRNase toxin WapA. Furthermore, utilizing the methionine analogue L-azidohomoalanine as a nutrient reporter, we provide evidence of nutrient extraction from Bacillus megaterium by Bacillus subtilis. Toxin delivery and nutrient extraction occur in a contact-dependent manner, and both activities are abolished in the absence of the phosphodiestrase YmdB, shown previously to mediate intercellular nanotube formation. Furthermore, we detect the localization of WapA molecules to nanotubes. Thus, we propose that Bacillus subtilis utilizes the same nanotube apparatus in a bidirectional manner, delivering toxin and acquiring beneficial cargo, thereby maximally exploiting potential niche resources.

Donor-delivered cell wall hydrolases facilitate nanotube penetration into recipient bacteria

“…We have previously shown that Bs kills Bm cells grown in proximity by delivering the tRNase toxin WapA via nanotubes 6 . We thus examined the ability of Bs to inhibit Bm growth, as a readout for establishment of interspecies nanotubes.…”

“…Bacteria produce various apparatuses to conduct intercellular molecular exchange, including transfer of DNA, toxin delivery, as well as nutrient acquisition 6,9,32,33 . However, it remains mysterious how an organelle that physically bridges two adjacent cells is being established to execute these functions.…”

“…By employing the Gram-positive soil bacterium Bacillus subtilis (Bs) as a model, we have previously described a type of contactdependent molecular trade mediated by intercellular membranous bridges, termed nanotubes 3 . Nanotubes were found to serve as conduits for intercellular exchange of metabolites, cytoplasmic proteins and even plasmids, hinting at their potential significance in shaping natural bacterial communities [3][4][5][6] . Further, utilizing these intercellular bridges, Bs could deliver the WapA tRNase toxin to, and acquire nutrients from, the opponent species B. megaterium (Bm) 6 .…”

“…Nanotubes were found to serve as conduits for intercellular exchange of metabolites, cytoplasmic proteins and even plasmids, hinting at their potential significance in shaping natural bacterial communities [3][4][5][6] . Further, utilizing these intercellular bridges, Bs could deliver the WapA tRNase toxin to, and acquire nutrients from, the opponent species B. megaterium (Bm) 6 . Intriguingly, nanotube-like structures were shown to facilitate trafficking of nutrients among various species, including Gram-positive and Gram-negative bacteria 7,8 , and even in a trans-kingdom manner between bacterial pathogens and mammalian host cells 9 .…”

Extracellular matrix components are required to protectBacillus subtilisfrom T6SS-dependentPseudomonasinvasion and modulate co-colonization of plants

“…Cells growing within a biofilm are in continuous contact with each other, as well as with their environment and other organisms living in the same ecological niche. Bacterial interactions are thus defined by a combination of different factors including the activation of different metabolic pathways in conjunction with the production and secretion of signaling compounds, siderophores, antibiotics and quorum sensing molecules 21, 22, 23, 24, 25, 26 . These compounds can be excreted outside the cells via bacterial secretion systems, efflux pumps, transporters and membrane vesicles.…”