Atroseptica Strain Research Articles

Purification and partial characterization of a mitomycin C-induced pectin lyase of Erwinia chrysanthemi strain EC183

Pectin lyase, produced by Erwinia chrysanthemi strain EC183 following mitomycin C treatment, was purified to near homogeneity from the culture lysate. The purification procedure involved ultrafiltration, ammonium sulphate fractionation and ion exchange chromatography on DEAE-BioGel A and CM-sepharose. The molecular weight and pI of the pectin lyase were estimated to be 34 500 and 9·45, respectively. The enzyme was most active on Link (98% esterified) pectin and least active on nonesterified pectic acid. Pectin lyase cleaved Link pectin in an endo manner, with optimum pH of 8·3 and optimum temperature of 33 †C. The Km and Vmax of the enzyme with Link pectin as the substrate were estimated to be 7·3±2·0 mg ml−1 and 47·6±10·7 A235 min−1, respectively. Antipectin lyase antibody reacted with pectin lyases from 11 of 12 E. chrysanthemi strains and all four Erwinia carotovora subsp. atroseptica strains tested but not with enzymatic preparations from E. carotovora subsp. carotovora, Erwinia milletiae, Erwinia rhapontici or Aspergillus sojae. These data indicate that pectin lyase of E. carotovora subsp. carotovora is immunologically distinct from that produced by E. chrysanthemi.

Enumeration of two competing Erwinia carotovora populations in potato tubers by a membrane filter‐immunofluorescence procedure

Relative increases in cell populations of specific Erwinia carotovora strains injected into potato tubers either singly or in combination of two strains were determined by depositing tissue extracts on membrane filters and staining cells of individual strains by immunofluorescence. The population increase of an Erw. carotovora subsp. atroseptica (Eca) strain was, in general, not affected by the presence of an Erw. carotovora subsp. carotovora (Ecc) strain. However, the increase of an Ecc strain was inhibited by the presence of an Eca strain, especially at incubation temperatures of 5° and 15°C but not at 26°C. One Ecc strain consistently increased in population over another Ecc strain at a greater rate when they were inoculated together at the same loci in comparison to when they were inoculated separately at different loci.