Abstract
Two polyunsaturated fatty acid (PUFA) producing strains (ACEM 6 and ACEM 9(T)) isolated from a temperate, humic-rich river estuary in Tasmania, Australia, were found to be members of the genus Shewanella. These strains were able to utilize humic compounds (tannic acid) and derivatives (2,6-anthraquinone disulfonate) as sole carbon sources and as electron acceptors for anaerobic respiration. The major fatty acids were typical of the genus Shewanella; however, PUFAs mostly made up of eicosapentaenoic acid were produced at high levels (10.2--23.6% of total fatty acids) and at relatively high incubation temperatures (10.2% at 24 degrees C). Sequence analysis indicated that ACEM 6 and ACEM 9(T) had identical 16S rDNA sequences and were most closely related to Shewanella japonica (sequence similarity 97.1%). DNA hybridization and phenotypic characteristics confirmed that the isolates constituted a novel species of the genus Shewanella, which is designated Shewanella olleyana sp. nov. (type strain ACEM 9(T)=ACAM 644(T)=LMG 21437(T)).