Paenibacillus larvae subspecies with dissimilar virulence patterns also group by vegetative growth characteristics and enolase isozyme biochemical properties

Paenibacillus larvae – the causal agent of American foul brood disease in Honey bees – group to different subspecies based upon disease progression and virulence as well as by molecular genotype. Vegetative growth studies reveal that virulence-grouped subspecies arrive at different saturated cell densities. In addition, strains segregating based upon virulence phenotype contain different genotypes in the locus encoding for the key glycolytic enzyme enolase. DNA sequence comparison of enolase loci from 7 Paenibacillus larvae strains identified 6 single-nucleotide polymorphisms (SNP) that segregated based on subspecies virulence classification. Only one polymorphism represented a change in amino acid coding (glycine or alanine) at position 331 of the protein. The kinetic properties of two recombinant enolase proteins expressed from enolase alleles isolated from different virulence classed strains (P. larvae ATCC 9545 and SAG 10367) yielded a Km and of 4.2μM and 1.5μM and Vmax of 16.2μmolmin−1mg−1 and 10.8μmolmin−1mg−1, respectively. Enolase from P. larvae SAG 10367 had a maximum reaction velocity lower than and a specificity constant approximately 1.6× higher than that of P. larvae ATCC 9545.