TABLE 2.

Population sizes and proportions of the epiphytic population of X. axonopodis pv. phaseoli aggregated in biofilms under three field conditions

Bean cv., yr of field exptPlant age (days after sowing)Sample size (no. of leaves)Mean log10 (X. axonopodis pv. phaseoli CFU/g [fresh wt]) (SEM)aMean B/(B + S)b (SEM)
EpiphyticSolitaryBiofilmTotal
Michelet, 199856123.20 (0.23)3.90 (0.28)3.74 (0.22)3.52 (0.33)14.44 (5.56)
6286.42 (0.32)6.21 (0.37)5.24 (0.27)6.56 (0.33)30.99 (11.59)
Michelet, 199927273.49 (0.22)3.75 (0.18)3.26 (0.16)3.75 (0.21)27.28 (2.86)
41185.23 (0.07)5.11 (0.07)4.73 (0.06)5.55 (0.07)31.22 (3.36)
56185.52 (0.09)5.61 (0.07)4.71 (0.07)5.91 (0.08)14.55 (3.18)
69186.00 (0.07)5.94 (0.06)4.66 (0.06)6.47 (0.07)6.08 (1.14)
Contender, 20002765.41 (0.91)5.25 (0.68)5.00 (0.58)5.96 (0.66)42.75 (17.97)
33124.38 (0.43)5.07 (0.46)4.64 (0.38)4.58 (0.35)43.94 (13.58)
48126.14 (0.27)6.07 (0.33)4.92 (0.24)6.38 (0.30)12.88 (5.54)
61125.74 (0.07)5.32 (0.23)4.47 (0.08)6.09 (0.08)16.65 (6.16)
82125.33 (0.17)5.70 (0.19)4.91 (0.14)5.54 (0.09)16.01 (4.07)
  • a The epiphytic bacterial population corresponds to the washing liquid of the leaflets. Filtration of this suspension leads to separation of the solitary component from the biofilm populations retained on filters. Total bacterial populations were quantified by stomaching leaflets for 2 min at maximum power.

  • b B/(B + S) represents the frequency of biofilm (B) bacterial component in the theoretical epiphytic population: biofilm + solitary (S). The epiphytic population size directly measured from leaves is given in the “Epiphytic” column.