Helicobacter pylori
genomes encode >60 predicted outer membrane proteins (OMPs). Several OMPs in the Hop family act as adhesins, but the functions of most Hop proteins are unknown. To identify
hop
mutant strains that exhibit altered fitness
in vivo
compared to fitness
in vitro
, we used a genetic barcoding method that allowed us to track changes in the proportional abundance of
H. pylori
strains within a mixed population. We generated a library of
hop
mutant strains, each containing a unique nucleotide barcode, as well as a library of control strains, each containing a nucleotide barcode in an intergenic region predicted to be a neutral locus unrelated to bacterial fitness. We orogastrically inoculated each of the libraries into mice and analyzed compositional changes in the populations over time
in vivo
compared to changes detected in the populations during library passage
in vitro
. The control library proliferated as a relatively stable community
in vitro,
but there was a reduction in the population diversity of this library
in vivo
and marked variation in the dominant strains recovered from individual animals, consistent with the existence of a non-selective bottleneck
in vivo
. We did not identify any OMP mutants exhibiting fitness defects exclusively
in vivo
without corresponding fitness defects
in vitro
. Conversely, a
babA
mutant exhibited a strong fitness advantage
in vivo
but not
in vitro
. These findings, when taken together with results of other studies, suggest that production of BabA may have differential effects on
H. pylori
fitness depending on the environmental conditions.
Neutral locus heterozygosity, inbreeding, and survival in Darwin's ground finches (Geospiza fortis and G. scandens)
