Subterranean environments are potential sources for the isolation of novel
microorganisms. Water and soil samples were collected at depths ranging fro
m 10 to 1800 meters below the surface, and screening was carried out with a
erobic rich and anaerobic minimal media. Two psychrotrophic anal three chem
oautotrophic strains were isolated. One of the psychrotrophic isolates, des
ignated SN16A, grew at temperatures between -5 and 37 degrees C with optima
l growth between 25 and 30 degrees C. The other psychrotroph, designated KB
700A, grew between -10 and 30 degrees C. Little difference in growth rate c
ould be observed between 20 and 30 degrees C; however, this strain did not
grow at 37 degrees C. KB700A utilized CO2 chemoautotrophically at 30 degree
s C, using hydrogen as an energy source. Both strains were characterized bi
ochemically. The complete 16S rRNA sequence of KB700A was 98.7% homologous
with that of Pseudomonas marginalis. However, the 16S rRNA of SN16A showed
only 95.4% identity at maximum-with the corresponding gene of Arthrobacter
globiformis-suggesting that this strain may belong to a novel genus. Both s
trains exhibited the ability to produce hydrolytic enzymes on plate assays.
Our results suggest that subterranean environments are promising sources f
or the isolation of psychrotrophic microorganisms.