Distribution and characteristics of Chromobacterium in the maritime and sub-antarctic

The distribution of Chromobacterium on islands of the Scotia Ridge and Antarctic Peninsula was monitored during 1975–81. Three groups of strains were recognized: (1) an acid-tolerant group at South Georgia (pH<4.6); (2) a group occurring between pH 4.6 and 6.0 which contained most terrestrial isolates; and (3) a group occurring in mineral material, lakes and their sediments where pH was invariably <6.1. Chromobacteria were rarely detected at moisture levels <500% dry weight. Occurrence of the genus has previously been under-estimated because of its poor competitive ability. Media selective for northern strains proved inhibitory and a new selective medium containing Nalidixic acid, Penicillin and 0/129 Pteridine derivative was developed. Distinctive taxonomic and antibiotic sensitivity patterns were recognized. Terrestrial Antarctic isolates were closely related to Chromobacterium (= Janthinobacterium) lividum but differed in certain diagnostic features. Most notable was the ability of Antarctic strains to produce acid from trehalose which is widespread in Antarctic micro-flora and -fauna. Antarctic isolates resisted significantly fewer antibiotics than the northern temperate type culture.