ý.,,: V. ý ýý . - Nottingham eTheses - University of Nottingham

seen to a certain extent in the ARDRA analysis (Fig. 5.2a & b) where isolate 494 forms
an outlier to the main Marinomonas group but shows a distant relationship with all other
groups in the assemblage.
5.3.2.6. -
The Psychrobacter group, isolate 583.
Isolate 583 was identified as belonging to the genus Psychrobacter using 16S rRNA
sequence analysis (Table 5.1). The closest relative was identified by comparison with the
Genbank database as Psychrobacterproteolyticus
(AJ272303), however this was
identified at 94% similarity (Table 5.1). P. proteolyticus was isolated from Antarctic
Krill, it is a 7-Proteobacterium belonging to the family Moraxellaceae (Denner et al..
2001). Therefore, the closest relative to this isolate was found in association with the
Antarctic marine environment and does exhibit the characteristics suitable for a cold-
adapted AFP active bacterium from a saline lake; it is psychrotrophic and halotolerant.
Isolate 583 was isolated from Triple Lake with a water temperature of -14°C and a
salinity of 175ppt, therefore the bacterium would need to be psychrotrophic and
halotolerant. However, it must be stated that this identification is based on the sequence
similarity of only 814bp (Table 5.1), which limited the confidence of this identification.
In the phylogenetic tree, isolate 583 was aligned against two close relatives from the
family Moraxellaceae (Psychrobacter sp. (AJ272303) and Moraxella lacunata
(AJ247228), Table 5.3) and clustered with the Moraxellaceae group. It was not closely
related to either of the two relatives but was closer to the Psychrobacter sp. compared
with Moraxella lacunata (Fig 5.4). This indicated that isolate 583 is probably an
unidentified member of the Psychrobacter genus, but until the complete 16S rRNA gene
has been sequenced this cannot be known. Duman & Olsen (1993) showed that
Micrococcus cryophilus, which is synonymous with Psychrobacter urativorans
(Cavanagh et al., 1996), demonstrated thermal hysteresis activity. M. cryophilus was
originally identified as a Gram positive large coccus (McLean et al., 1951), however, the
Gram stain was variable and was shown to be predominantly Gram negative and as such
was re-grouped into the Psychrobacter genus, which is characterised by Gram negative.
aerobic, oxidase positive coccobacilli (Juni & Heym. 1986; Cavanagh et al., 1996).
Psvchrobacter urathvorans was isolated from ornithogenic soils (derived from the
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