Use of beta-ionone in enrichment cultures for isolating Paracolobactrum and certain fungi from soil.

Abstract

Beta-ionone, an acyclic terpene used extensively in perfumery, was used in enrichment media for isolation and study of certain soil microorganisms. Two-tenths per cent beta-ionone inhibited the growth of about 99% of the bacterial and fungal population. Fungi were more sensitive than bacteria to beta-ionone. The most frequent bacterial isolates obtained from media enriched with beta-ionone were representatives of the genus Paracolobactrum. A few of these isolates were identical with the type species, P. aerogenoides, but the majority differed by their ability to liquefy gelatin. This difference may provide an adequate basis for establishing a new species in this genus which, because of its similarity to Aerobacter cloacae, tentatively may be designated as Paracolobactrum cloacanoides nomen provisorium. Other coliform bacteria were isolated but with reduced frequency. Fusarium species and Trichoderma viride were the fungi isolated most frequently from soil samples plated on beta-ionone-enriched media. Geotrichum candidum and Scopulariopsis brevicaulis were isolated from specific soils using this enrichment procedure. A single isolate from soil was made of Curvularia pallescens, which previously has been isolated only once, from soil in India.