232
that colonizer progeny tends not to colonize the particle but stay near it by chemotaxis. This is
consistent with the suggestion of Dawson et al. (1981) that small starved cells readily attach to
surfaces but not to nutrient replete bacteria (those in the particle's microenvironment?). Further,
it is likely that antagonistic interactions on the colonized particle tend to reduce bacterial
diversity. It would be an adaptive strategy for the attached bacteria to release chemicals to
discourage the presence of other species in the vicinity of the particle so that the progeny of the
attached bacteria may monopolize the DOM emanating from the particle.
Ingestion 0/ firmly attached bacteria by metazoa: A survival strategy 0/ bacteria?
The scenario of POM utilization by bacteria which we have described does not preclude the
possibility, no probability, that at some stage in the life of the colonized particle a metazoan will
eat it, bacteria and all. What strategies might bacteria use to "prevent death"? It has been
suggested (Robison et al., 1977) that luminous bacteria attached to (nutritionally spent?) particles
emit light to announce their presence, so that they may pass into the organically rich fecal
material where they may proliferate. A necessary condition the success of this strategy is that
at least some bacteria must survive passage through the animal gut. One might hypothesize that
an adaptive strategy for particle-attached bacteria would be to make some digestion-resistent
variants (a thicker cell wall might suffice; e.g. gram-negative marine bacteria of the genus
Synechococcus are not digestible by copepods; Johnson et al., 1982; Silver and Bruland, 1982;
Silver and Alldredge, 1982; Iturriaga and Mitchell, 1986). The digestion-resistent cells could
serve as an inoculum into the metazoan feces then proliferate and propagate the normal
(digestible) phenotype. Why has there not been a selection for digestion-resistence, via the
production of a thick cell wall, in heterotrophic bacteria? A thick wall may limit DOM uptake,
hence its acquisition would be selectively negative in heterotrophic bacteria but not in
photosynthetic bacteria.
Biogeochemical implications 0/ POM-bacteria interactions
Large-scale solubilization of POM by bacterial hydrolases could have fundamental implications
for the patterns of material flux in the ocean. Carbon flow in the "enzyme pathway" involves
that colonizer progeny tends not to colonize the particle but stay near it by chemotaxis. This is
consistent with the suggestion of Dawson et al. (1981) that small starved cells readily attach to
surfaces but not to nutrient replete bacteria (those in the particle's microenvironment?). Further,
it is likely that antagonistic interactions on the colonized particle tend to reduce bacterial
diversity. It would be an adaptive strategy for the attached bacteria to release chemicals to
discourage the presence of other species in the vicinity of the particle so that the progeny of the
attached bacteria may monopolize the DOM emanating from the particle.
Ingestion 0/ firmly attached bacteria by metazoa: A survival strategy 0/ bacteria?
The scenario of POM utilization by bacteria which we have described does not preclude the
possibility, no probability, that at some stage in the life of the colonized particle a metazoan will
eat it, bacteria and all. What strategies might bacteria use to "prevent death"? It has been
suggested (Robison et al., 1977) that luminous bacteria attached to (nutritionally spent?) particles
emit light to announce their presence, so that they may pass into the organically rich fecal
material where they may proliferate. A necessary condition the success of this strategy is that
at least some bacteria must survive passage through the animal gut. One might hypothesize that
an adaptive strategy for particle-attached bacteria would be to make some digestion-resistent
variants (a thicker cell wall might suffice; e.g. gram-negative marine bacteria of the genus
Synechococcus are not digestible by copepods; Johnson et al., 1982; Silver and Bruland, 1982;
Silver and Alldredge, 1982; Iturriaga and Mitchell, 1986). The digestion-resistent cells could
serve as an inoculum into the metazoan feces then proliferate and propagate the normal
(digestible) phenotype. Why has there not been a selection for digestion-resistence, via the
production of a thick cell wall, in heterotrophic bacteria? A thick wall may limit DOM uptake,
hence its acquisition would be selectively negative in heterotrophic bacteria but not in
photosynthetic bacteria.
Biogeochemical implications 0/ POM-bacteria interactions
Large-scale solubilization of POM by bacterial hydrolases could have fundamental implications
for the patterns of material flux in the ocean. Carbon flow in the "enzyme pathway" involves