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Title: Molecular identification and physiological characterisation of bacteria adapted to grow at high salinity
Author: Abubaker, Nagah Suleman
ISNI:       0000 0004 2725 107X
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2010
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Three strains (AM7, JC33 and NW53) were isolated from an oil pipeline in Kuwait using rich medium and aerobic incubation. 16S rDNA sequencing was used to identify the strains as Bacillus licheniformis (AM7, 98.9% identity), Staphylococcus pasteuri (Je33, 98.8%) and Brevibacterium stationis (97.9%). Due to their origin from oil pipeline samples, the strains were tested for their ability to grow as biofilms on filter paper on agar plates and also by using the microtitre assay. All three strains were able to form biofilms on filter paper and in microtitre plates. Biofilm and planktonic growth of the three strains was determined at different temperatures, pH values and salinities J and optimum values for biofilm and planktonic growth were determined. The response of the three strains to salinity was carried out, because it was known that seawater and groundwater were used to propel the oil to the refinery. Using rich LB medium, all three strains grew well at 1 M NaCI and after adaptation, good growth was found at salinities up to 3 M NaCl for B. licheniformis and S. pasteuri. Growth was also found for Br. stationis at 3 M NaCl, but it was significantly less than at the lower salinities. Further studies on salinity tolerance were carried out on Br. stationis, since this was the least characterised of the three strains isolated. NMR analyses were used to determine the compatible solutes used by Br. stationis when grown on M9 minimal medium. It was found that glycine betaine (betaine) was the major compatible solute, but that proline and an unknown sugar were also present at high salinities, when glucose was the carbon source. When betaine was the carbon source, only betaine was accumulated as a compatible solute. When the compatible solute ectoine was used as the sole source of carbon in M9 medium, ectoine was the dominant compatible solute at low salinities, but betaine was still accumulated at high salinities. These results suggest that betaine is the major compatible solute used by Br. station is. Further characterisation of Br. stationis involved measuring NADH oxidase activity in crude cell-free extracts to examine the effects oftemperature and salinity on intracellular enzyme activity.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available