Composition of the phylloplane bacterial flora of some agricultural plants in Egypt

Abstract

Summary Populations of heterotrophic bacteria inhabiting the phylloplane of six agricultural plants were estimated, using a dilution technique. Bacterial populations irregularly fluctuated, but counts in the winter growing season were generally low, compared with counts obtained in summer. Maximum counts were obtained in April and August at the beginning of either ageing of grasses or flowering of the other plant species. More than 450 isolates were examined and most found to be aerobic spore-formers and chromogenic cocci. Members of Bacillaceae and Micro-coccaceae occasionally amounted to > 60% and > 30%, respectively, of the total bacterial counts. Gram-positive and Gram-negative rods were less frequent and substantially fewer actinomycetes were isolated from the phylloplane. The bacterial population consisted of relatively few taxa and the variations in their incidence were due to changes in their relative abundance. Strains of Bacillus cereus, B. licheniformis, Staphylococcus aureus, Micrococcus flavus, and Pseudomonas spp. were consistently isolated from phylloplane. The species composition and the relative numbers of phylloplane bacterial flora are compared with descriptions of the microflora, isolated from leaves of other plants.