[compost_tea] interesting reports from APS

From: tomjasz <tom_at_livesoil.com>
Date: Tue, 05 Oct 2004 18:23:28 -0000

Influence of indigenous bacteria on survival of human pathogens on
plants. C. POZA-CARRIÓN and S. E. Lindow. University of California,
Berkley. Phytopathology 94:S128. Publication no. P-2004-0060-SSA.

Although generally associated with consumption of meat products,
numerous food-borne diseases caused by Salmonella enterica serotypes
and Escherichia coli O157:H7 have been associated with contaminated
fruits and vegetables in the United States, as well as in many other
countries. The surfaces of plants are normally colonized by large
numbers of bacteria, called epiphytes, which include plant pathogens
and other saprophytic and beneficial bacteria. Preliminary studies
have shown that while E. coli and Salmonella strains can grow on
plants under conditions of continuous free moisture, they are
hypersensitive to the stress of dry leaf surfaces compared to other
bacteria more commonly found on plants, indicating that stress
tolerance is a determining factor in their epiphytic colonization.
Extrinsic factors such as patterns of colonization of plants also
have a great impact on the survival of bacteria on leaves. Cells of
Pseudomonas syringae in aggregates on leaves were much more stress
tolerant than solitary cells and the survival of immigrants of P.
syringae to leaves was greatly enhanced if cells were deposited onto
pre-existing aggregates of a variety of bacteria on plants. The
survival of Salmonella enterica subsp. enterica serovar Montevideo
and serovar Enteritidis and Escherichia coli O157:H7 inoculated onto
lettuce and cilantro leaves was often strongly influenced by the
number and strain identity of indigenous epiphytic bacteria
preexisting on a leaf. We will also discuss fluorescence microscopic
studies that address the role of bacterial cell aggregates in
survival of such strains at small spatial scales.






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Received on Tue Oct 05 2004 - 15:36:23 EDT

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