title: High local substrate availability stabilizes a cooperative trait.
abstract: Cooperative behavior is widely spread in microbial populations. An example is the expression of an extracellular protease by the lactic acid bacterium Lactococcus lactis, which degrades milk proteins into free utilizable peptides that are essential to allow growth to high cell densities in milk. Cheating, protease-negative strains can invade the population and drive the protease-positive strain to extinction. By using multiple experimental approaches, as well as modeling population dynamics, we demonstrate that the persistence of the proteolytic trait is determined by the fraction of the generated peptides that can be captured by the cell before diffusing away from it. The mechanism described is likely to be relevant for the evolutionary stability of many extracellular substrate-degrading enzymes.
authors.affiliation: NIZO Food Research, Health Department, Ede, The Netherlands.
authors.forename: Herwig
authors.initials: H
authors.lastname: Bachmann
authors.forename: Douwe
authors.initials: D
authors.lastname: Molenaar
authors.forename: Michiel
authors.initials: M
authors.lastname: Kleerebezem
authors.forename: Johan E T
authors.initials: JE
authors.lastname: van Hylckama Vlieg
mesh_terms: D000818:Animals; D010450:Endopeptidases / Q000378:metabolism*; D017930:Genes, Reporter; D013294:Lactococcus lactis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D056265:Microbial Interactions; D008892:Milk / Q000382:microbiology*; D008894:Milk Proteins / Q000378:metabolism*; D008954:Models, Biological; D011157:Population Dynamics; D013379:Substrate Specificity
chemical_list: D008894:Milk Proteins; D010450:Endopeptidases