Daniel P. Keymer,* Lilian H. Lam, and Alexandria B. Boehm
Jerry Yang & Akiko
Yamazaki Environment & Energy Building #M-16, 473 Via Ortega,
MC: 4020, Stanford, CA 94305.
Vibrio cholerae strains are capable of inhabiting multiple niches in the aquatic environment and in some
cases cause disease in humans. However, the ecology and biodiversity of these bacteria in environmental
settings remains poorly understood. We used the genomic fingerprinting technique enterobacterial repetitive
intergenic consensus sequence PCR (ERIC-PCR) to profile 835 environmental isolates from waters
and sediments obtained at nine sites along the central California coast. We identified 115 ERIC-PCR
genotypes from 998 fingerprints, with a reproducibility of 98.5% and a discriminatory power of 0.971.
When the temporal dynamics at a subset of sampling sites were explored, several genotypes provided
evidence for cosmopolitan or geographically restricted distributions, and other genotypes displayed
nonrandom patterns of cooccurrence. Partial Mantel tests confirmed that genotypic similarity of isolates
across all sampling events was correlated with environmental similarity (0.04 ≤ r ≤ 0.05), temporal
proximity (r = 0.09), and geographic distance (r = 0.09). A neutral community model for all sampling
events explained 61% of the variation in genotype abundance. Cooccurrence indices (C-score, C-board,
and Combo) were significantly different than expected by chance, suggesting that the V. cholerae population
may have a competitive structure, especially at the regional scale. Even though stochastic processes
are undoubtedly important in generating biogeographic patterns in diversity, deterministic factors appear
to play a significant, albeit small, role in shaping the V. cholerae population structure in this system.
Keywords:Vibrio cholerae,genomic and phenotypic diversity,Nucleotide,pathogens.