The extracellular matrix protects Bacillus subtilis colonies from Pseudomonas invasion and modulates plant co-colonization

Nat Commun. 2019 Apr 23;10(1):1919. doi: 10.1038/s41467-019-09944-x.

Abstract

Bacteria of the genera Pseudomonas and Bacillus can promote plant growth and protect plants from pathogens. However, the interactions between these plant-beneficial bacteria are understudied. Here, we explore the interaction between Bacillus subtilis 3610 and Pseudomonas chlororaphis PCL1606. We show that the extracellular matrix protects B. subtilis colonies from infiltration by P. chlororaphis. The absence of extracellular matrix results in increased fluidity and loss of structure of the B. subtilis colony. The P. chlororaphis type VI secretion system (T6SS) is activated upon contact with B. subtilis cells, and stimulates B. subtilis sporulation. Furthermore, we find that B. subtilis sporulation observed prior to direct contact with P. chlororaphis is mediated by histidine kinases KinA and KinB. Finally, we demonstrate the importance of the extracellular matrix and the T6SS in modulating the coexistence of the two species on melon plant leaves and seeds.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacillus subtilis / genetics*
  • Bacillus subtilis / growth & development
  • Bacillus subtilis / metabolism
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Colony Count, Microbial
  • Cucurbitaceae / microbiology*
  • Extracellular Matrix / metabolism*
  • Gene Expression Regulation, Bacterial*
  • Microbial Interactions / genetics*
  • Phosphotransferases / genetics
  • Phosphotransferases / metabolism
  • Plant Leaves / microbiology
  • Protein Kinases / genetics
  • Protein Kinases / metabolism
  • Pseudomonas chlororaphis / genetics*
  • Pseudomonas chlororaphis / growth & development
  • Pseudomonas chlororaphis / metabolism
  • Seeds / microbiology
  • Spores, Bacterial / genetics
  • Spores, Bacterial / growth & development
  • Spores, Bacterial / metabolism
  • Symbiosis / physiology
  • Type VI Secretion Systems / genetics
  • Type VI Secretion Systems / metabolism

Substances

  • Bacterial Proteins
  • Type VI Secretion Systems
  • kinA protein, Bacillus subtilis
  • Phosphotransferases
  • Protein Kinases
  • kinB protein, Bacillus subtilis