Characterization ofPseudomonas geomorphus: A novel groundwater bacterium.

Strain ABS10, a Gram-negative, pleomorphic bacterium isolated from a pristine aquifer in Ada, Oklahoma, was studied as a candidate for the introduction and expression of plasmid DNA in a native ground water isolate. This organism was originally typed as anArthrobacter sp. due to its morphological phase change and Gram-variable reaction upon Gram staining. The fatty acid methyl ester profile of ABS10 revealed a high similarity withPseudomonas putida. DNA-DNA hybridization showed 81% homology between ABS10 andP. putida. 16S rRNA sequence analysis showed ABS 10 to be a member of the Gamma division of the purple photosynthetic bacteria. The organism has been designatedPseudomonas geomorphus due to its isolation from a subterranean sample and the morphological phase change from rods in young cultures to cocci in older cultures. The broad host range plasmid RP4 was introduced into ABS10 and stably maintained, indicating that RP4 may serve as a vehicle for the introduction of catabolic genes into this organism.