Publication Date:
2022-05-25
Description:
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2010
Description:
Predatory bacteria are ubiquitous in aquatic environments and may be important players
in the ecology and biogeochemistry of microbial communities. Three novel strains
belonging to two genera of marine flavobacteria, Olleya and Tenacibaculum, were
cultured from coastal sediments and found to be predatory on other bacteria on surfaces.
Two published species of the genus Tenacibaculum were also observed to grow by lysis
of prey bacteria, raising the possibility that predation may be a widespread lifestyle
amongst marine flavobacteria, which are diverse and abundant in a variety of marine
environments. The marine flavobacterial clade is known to include species capable of
photoheterotrophy, scavenging of polymeric organic substances, pathogenesis on
animals, the degradation and lysis of phytoplankton blooms and, now, predation on
bacterial communities. Strains from the two genera were found to exhibit divergent prey
specificities and growth yields when growing predatorily. Olleya sp. predatory cells
accumulated to an order of magnitude greater cell densities than Tenacibaculum sp. cells
on equivalent prey cell densities. Experiments were conducted to constrain the potential
of the novel isolates to affect prey communities under more environmentally relevant
conditions. An investigation of the minimum number of predatory cells needed to
generate clearings of prey cells found that the inoculation of individual predatory
flavobacteria cells can ultimately result in dense lytic swarms. In some cases, the
susceptibility of particular prey species to lysis by a flavobacterial predator was found to
vary based on the growth state of the prey cells or the presence of their spent growth
media. A novel methodology for the experimental study of biofilms was used to assess
the impact of exposure to predatory marine flavobacteria on the release of macronutrients
from prey biofilms. The Olleya sp. predator had a stimulative effect on macronutrient
release while the Tenacibaculum sp. did not, further suggesting the two groups of
predators are adapted to different ecological niches.
Description:
Support by the National Science
Foundation (NSF) Division of Molecular and Cellular Biosciences Grant (MCB-
0348425), the MIT Student Assistance Fund, the Woods Hole Oceanographic Institution
(WHOI) Academic Programs Office, WHOI Coastal Ocean Institute (COI) and WHOI Ocean Venture Fund grant,
COI and the WHOI Ocean Life Institute.
Keywords:
Predation
;
Marine bacteria
Repository Name:
Woods Hole Open Access Server
Type:
Thesis
Format:
application/pdf
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