title: Predatory prokaryotes:  predation and primary consumption evolved in bacteria.
abstract: Two kinds of predatory bacteria have been observed and characterized by light and electron microscopy in samples from freshwater sulfurous lakes in northeastern Spain.  The first bacterium, named Vampirococcus, is Gram-negative and ovoidal (0.6 micrometer wide).  An anaerobic epibiont, it adheres to the surface of phototrophic bacteria (Chromatium spp.) by specific attachment structures and, as it grows and divides by fission, destroys its prey.  An important in situ predatory role can be inferred for Vampirococcus from direct counts in natural samples.  The second bacterium, named Daptobacter, is a Gram-negative, facultatively anaerobic straight rod (0.5 x 1.5 micrometers) with a single polar flagellum, which collides, penetrates, and grows inside the cytoplasm of its prey (several genera of Chromatiaceae).  Considering also the well-known case of Bdellovibrio, a Gram-negative, aerobic curved rod that penetrates and divides in the periplasmic space of many chemotrophic Gram-negative bacteria, there are three types of predatory prokaryotes presently known (epibiotic, cytoplasmic, and periplasmic).  Thus, we conclude that antagonistic relationships such as primary consumption, predation, and scavenging had already evolved in microbial ecosystems prior to the appearance of eukaryotes.  Furthermore, because they represent methods by which prokaryotes can penetrate other prokaryotes in the absence of phagocytosis, these associations can be considered preadaptation for the origin of intracellular organelles.
authors.affiliation: Department of Microbiology, Autonomous University of Barcelona, Bellaterra, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Guerrero
authors.forename: C
authors.initials: C
authors.lastname: Pedros-Alio
authors.forename: I
authors.initials: I
authors.lastname: Esteve
authors.forename: J
authors.initials: J
authors.lastname: Mas
authors.forename: D
authors.initials: D
authors.lastname: Chase
authors.forename: L
authors.initials: L
authors.lastname: Margulis
mesh_terms: D001501:Bdellovibrio / Q000145:classification* / Q000166:cytology / Q000502:physiology; D005075:Biological Evolution; D002844:Chromatium / Q000166:cytology / Q000502:physiology*; D005618:Fresh Water / Q000382:microbiology; D016964:Gram-Negative Anaerobic Cocci / Q000145:classification* / Q000166:cytology / Q000502:physiology; D016965:Gram-Negative Anaerobic Straight, Curved, and Helical Rods / Q000145:classification* / Q000166:cytology / Q000502:physiology; D006862:Hydrogen Sulfide; D011235:Predatory Behavior; D013030:Spain; D013559:Symbiosis; D014871:Water Microbiology
chemical_list: D006862:Hydrogen Sulfide