plant surface microbiology.pdf

4 Microorganisms on the Rhizosphere Microcosm 63
Fig. 8. Bacterial colonising AM hyphae of Glomus etunicatum in 1 % water-agar. BC Bacteria
colonies, H hyphae. A General aspects of mycelia colonised by bacteria (x20), B corresponds
to black box indicated in the A, where bacteria is growing around hyphae
(x100), C bacteria growing around hyphae (x400)
In the soil, Andrade et al. (1997) observed sorghum plants inoculated with
several exotic or native Glomus species either exotic or native to the test soil.
The soils adhering to the root were considered rhizosphere or not adhering to
the root were considered hyphosphere. Bacterial numbers were greater in
rhizo- than in hyphosphere soil. Isolates of Bacillus and Arthrobacter were
most frequent in hyphosphere and Pseudomonas in rhizosphere soils. More
bacterial species were found in hyphosphere than in rhizosphere soil, and
bacterial communities varied within and among AM treatments. The development
of the AM mycelium in soil had little influence on the composition of
the microflora in the hyphosphere, while AM root colonisation was positively
related with bacterial numbers in the hyphosphere and with the presence of
Pseudomonas in the rhizosphere.
In another experiment, Andrade et al. (1998) inoculated Alcaligenes eutrophus
and Arthrobacter globiformis in sorghum plants. The first is an isolate
of the Glomus mosseae hyphosphere and the second an isolate of the G.
mosseae and G. intraradices mycorrhizosphere. Ten days after inoculation,