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Appl Environ Microbiol. 1983 April; 45(4): 1380-1388
Copyright © 1983, American Society for Microbiology. All Rights Reserved.

Ensifer adhaerens Predatory Activity Against Other Bacteria in Soil, as Monitored by Indirect Phage Analysis

James J. Germida and L. E. Casida Jr.

¹ Department of Soil Science, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N OWO, and Microbiology Program, Pennsylvania State University, University Park, Pennsylvania 16802²

ABSTRACT

An indirect phage analysis procedure was used to detect and follow the activity of the bacterial predator Ensifer adhaerens in situ in natural soil. The soil was percolated with an aqueous suspension of washed bacterial host cells so that the E. adhaerens cells naturally present in the soil would multiply in response to the host cells. The natural phage development which ensued against these multiplying E. adhaerens cells in the soil was then monitored by noting plaques which developed when the percolation fluid was plated with laboratory strains of E. adhaerens on laboratory media. The activities of the other members of the predation system that includes E. adhaerens (Streptomyces sp. strain 34 and a myxobacter) could not be monitored directly by phage analysis because phage were not found for them. Indirect monitoring was possible, however, because they were susceptible to attack by E. adhaerens. In general, the results were in agreement with previous observations by other methods of the predation sequence. E. adhaerens attacked Micrococcus luteus, Streptomyces sp. strain 34, and the myxobacter but did not attack several other possible species of hosts. It also did not respond to percolation of the soil with various nutrient solutions. E. adhaerens phage activity was not present in half of the soils percolated with M. luteus cells. This seemed to reflect too great a phage-host specificity for the technique as regards these soils, because E. adhaerens-like bacteria other than the strains used for plaquing were present in at least some of these soils. Although E. adhaerens did not attack Escherichia coli or Pseudomonas aeruginosa in soil, there was an overproduction of E. adhaerens phage if these bacteria were percolated simultaneously with M. luteus cells. The possibility is discussed that this represents an activation by M. luteus (or by a heat-extractable factor from it) of other bacterial predators that attack E. coli or P. aeruginosa and that these predators subsequently are themselves attacked by E. adhaerens.

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FOOTNOTES

Paper no. 6531 of the Pennsylvania Agriculture Experimental Station and contribution no. R318 of the Saskatchewan Institute of Pedology.

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Appl Environ Microbiol. 1983 April; 45(4): 1380-1388
Copyright © 1983, American Society for Microbiology. All Rights Reserved.

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