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

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The closest published relative for each isolate was determined by comparison with the<br />

Genbank nucleotide database using the FASTA (http: //www. ebi. ac. uk) and BLAST<br />

(Basic Local Alignment Search Tools) search algorithms which compare multiple<br />

nucleotide sequences for sequence similarity and homology (Altschul et al., 1990).<br />

Isolates, 124,154,214,5ice3,54,744<br />

and 794 were all 100% identical to<br />

Marinomonasprotea<br />

(AJ238597), confirming that these are all one species. Similarly<br />

isolates, 86 and 39 were 99.4% and 99.6% identical respectively to an unspeciated<br />

Pseudoalteromonas sp. (U85856); therefore it is probable that these two isolates were the<br />

same species. Isolates 33 and 302 were identified as an Antarctic seawater bacterium<br />

(AJ293825) and Pseudomonas fluorescens (AF228367) respectively. However, isolate<br />

33 was also 97.8% related to an unspeciated Pseudomonas sp. (AB021318) and therefore<br />

shows a close relationship with isolate 302. Isolate 302 has been further identified as<br />

Pseudomonasfluorescens by culturing the bacterium on Pseudomonas agar F<br />

(fluorescens agar) and CFC agar (Table 5.2; Bridson, 1998). Isolate 33 was identified as a<br />

pseudomonad but did not produce fluorescein pigment. Pseudomonas agar F stimulates<br />

the production <strong>of</strong> fluorescein and reduces that <strong>of</strong> pyocyanin and/or pyorubin and<br />

therefore delineates between pseudomonads which produce fluorescein and those which<br />

produce pyocyanin and/or pyorubin. CFC agar selects for pseudomonads whilst<br />

inhibiting most other bacteria.<br />

Isolates 492 and 47 showed more than 99% similarity to Stenotrophomonas<br />

maltophilia (Ac. No. AJ293464). However, the sequence data for isolate 492 only<br />

comprised 408 bp and so were not sufficient to make a definitive identification (genus<br />

identification is supported by ARDRA, discussed in section 5.3.2.4). However.<br />

identification <strong>of</strong> isolate 47 was based on 1182 bp and was therefore sufficient for putati\ e<br />

speciation. Isolate 732 showed 99.5% similarity to Enterobacter agglomerans<br />

(AF348161) based on 1493 bp, which is nearly a complete gene sequence, it is therefore<br />

unlikely that this identification would be inaccurate. Isolate 53 was identified as 99.3%<br />

related to Idiomarina loihiensis, which is a hydrothermal vent bacterium. Isolate 494 was<br />

100% related to an unidentified Sphingomonas sp (AF395031). However. this<br />

137

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