Abstract
Among horizontally acquired symbioses, the mechanisms underlying microbial strain- and species-level specificity remain poorly understood. Here, confocal-microscopy analyses and genetic manipulation of the squid–vibrio association revealed quantitative differences in a symbiont's capacity to interact with the host during initial engagement. Specifically, dominant strains of Vibrio fischeri, ‘D-type’, previously named for their dominant, single-strain colonization of the squid's bioluminescent organ, were compared with ‘S-type’, or ‘sharing’, strains, which can co-colonize the organ. These D-type strains typically: (i) formed aggregations of 100s–1000s of cells on the light-organ surface, up to 3 orders of magnitude larger than those of S-type strains; (ii) showed dominance in co-aggregation experiments, independent of inoculum size or strain proportion; (iii) perturbed larger areas of the organ's ciliated surface; and, (iv) appeared at the pore of the organ approximately 4×s more quickly than S-type strains. At least in part, genes responsible for biofilm synthesis control the hyperaggregation phenotype of a D-type strain. Other marine vibrios produced relatively small aggregations, while an array of marine Gram-positive and -negative species outside of the Vibrionaceae did not attach to the organ's surface. These studies provide insight into the impact of strain variation on early events leading to establishment of an environmentally acquired symbiosis.
Original language | English (US) |
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Pages (from-to) | 3269-3283 |
Number of pages | 15 |
Journal | Environmental Microbiology |
Volume | 21 |
Issue number | 9 |
DOIs | |
State | Published - 2019 |
Funding
We thank T Carvalho for technical assistance with transmission electron microscopy, M Flaherty for the construction of the sypQ complementation plasmid, and A Tischler for the construction of the ES114 ΔsypQ::EmR mutant. This study was made possible with funding from the National Institutes of Health grants R37 AI150661 (to M McFall-Ngai and EG Ruby), R01 OD11024 (to EG Ruby and M McFall-Ngai) and GM114288 (to K Visick).
ASJC Scopus subject areas
- Microbiology
- Ecology, Evolution, Behavior and Systematics