Streptomyces costaricanus sp. nov., Isolated from Nematode-Suppressive Soil

A new bacterial strain, strain CR-43T (T = type strain), which was isolated from tropical soil and was previously shown to have antinematodal and antibiotic properties, is described. The name Streptomyces costaricanus is proposed for this organism. The generic placement of strain CR-43T was based on its typical morphology, its production of LL-diaminopimelic acid, and its fatty acid composition. To clarify the taxonomic position of strain CR-43T, it was compared with the type strains of similar Streptomyces species. The results of a number of biochemical tests and a profile analysis of the hydrolyzable fatty acids indicated that CR-43T differs from previously described species. Strain CR-43 (= ATCC 55274 = NRRL B-16897) is the type strain of S. costaricanus sp. nov. Nematode-suppressive soils have been found in several locations throughout the world. In our laboratory, microorganisms with antinematodal or antifungal properties have been isolated from suppressive soils obtained from Mexico (12, 23) and Costa Rica (4). The biological basis of this suppressiveness was established by showing that heat sterilization abolishes the suppressive effect. One of the organisms isolated from suppressive soil obtained from Costa Rica exhibited both antinematodal and antifungal activities in laboratory, greenhouse, and field trials (4). A culture of this organism (designated strain CR-43T [T = type strain]) was submitted for identification to the American Type Culture Collection (ATCC), Rockville, Md., which concluded that the isolate was a member of the genus Streptomyces and could not be placed in a previously described species (1). Later, a University of Massachusetts research team reported (4) that this isolate specifically inhibited reproduction of the free-living nematode Caenorhabditis elegans in vitro under axenic conditions. Such an effect is referred to as antinematodal activity, in contrast to the nematicidal activity exhibited by organisms such as Streptomyces avermitilis. On the basis of the results of successful field trials in which the control of several species of plant parasites was examined, an application for a patent for CR-43T as a biocontrol agent for nematodes was filed by Research Corporation Technologies, Tucson, Ark, under exclusive license from the University of Massachusetts at Amherst. Cryopreserved subcultures of CR43T have been deposited in the ATCC (as ATCC 55274T) and in the U.S. Department of Agriculture Agricultural Research Service Culture Collection (as NRRL B-16897T). In this paper we describe CR-43T as a member of a new species, for which we propose the name Streptomyces costancanus. This organism was compared with plant-pathogenic, anthelmintic, and other similar Streptomyces species.