High diversity among environmental Escherichia coli isolates from a bovine feedlot.
Approximately 280 Escherichia coli isolates were isolated from a bovine feedlot at the University of Connecticut campus via enrichment in lauryl tryptose broth and random selection from MacConkey plates. The E. coli subspecies diversity was estimated by employing whole-cell BOX-PCR genomic fingerprints. A total of 89 distinct operational taxonomic units (OTUs) were identified by employing a criterion of 85% fingerprint similarity as a surrogate for an OTU, while the Chao1 index estimated the E. coli population richness at 128 OTUs. One genotype (at a similarity level of 60%) dominated the population at 66% regardless of sampling depth or location, while no significant vertical distribution pattern was observed in terms of genotype, mobility, antibiotic resistance profile, or biofilm-forming ability. Motility, measured by a soft agar assay, had a very broad range among the E. coli population and was positively correlated with biofilm-forming ability in minimal medium (Spearman's rank correlation coefficient r = 0.619, P < 10(-4)) but not in Luria broth. Only an estimated 48% of the population possessed gene agn43, which encodes Ag43, a phase-variable outer membrane protein that has been implicated in biofilm formation in minimal medium. We observed significantly more biofilm formation in both minimal medium and Luria broth for agn43(+) strains, with a larger effect in minimal medium. This study represents an exhaustive inventory of extant E. coli population diversity at a bovine feedlot and reveals significant subspecies heterogeneity in interfacial behavior.
Microbiology Program, Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut 06269, USA.
Hsiao-Hui
HH
Yang
Robert T
RT
Vinopal
Domenico
D
Grasso
Barth F
BF
Smets
D018829:Adhesins, Bacterial / Q000235:genetics; D018830:Adhesins, Escherichia coli / Q000235:genetics; D000821:Animal Feed / Q000382:microbiology*; D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D001483:Base Sequence; D018441:Biofilms / Q000254:growth & development; D002417:Cattle; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D004755:Enterobacteriaceae / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D004783:Environmental Microbiology; D004926:Escherichia coli / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D029968:Escherichia coli Proteins / Q000235:genetics; D036781:Fimbriae Proteins / Q000235:genetics; D005798:Genes, Bacterial; D014644:Genetic Variation; D005838:Genotype; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012988:Soil Microbiology; D013045:Species Specificity
D018829:Adhesins, Bacterial; D018830:Adhesins, Escherichia coli; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C118376:antigen 43, E coli; C058769:fimH protein, E coli; D036781:Fimbriae Proteins