Psychrophilic Bacteria from Antarctic Sea-ice and Phospholipis of Antarctic sea ice algal communities new sources of PUFAEntry ID: ASAC_708
Abstract: Metadata record for ASAC projects 161 and 708. (ASAC_161, ASAC_708).
1993: 39 sea-ice cores were collected from 22 sample locations off the Vestfold Hills during October-November. Bacteria were isolated on-station from 16 of these cores. Remaining cores were frozen for later examination.
1994: 49 sea-ice cores and 41 associated brine samples were collected from various locations off the Vestfold ... Hills during October-December.
1. 124 bacterial strains were isolated from the 16 cores initially examined. Microbiological tests have been conducted allowing identification to genus level. Strains of particular interest have been preserved in ACAM.
2. Temperature/growth profiles were determined for 4 strains, and the salinity/growth profile for one strain.
3. Lipid analysis was conducted on 24 strains.
4. 6 strains were examined for the production of compatible solutes.
5. DNA analysis was conducted on 3 strains of particular interest.
6. Purification and structural elucidation of a novel hydrocarbon was commenced.
7. Temperature and nutrient effects on polyunsaturated fatty acid production were investigated.
8. Three months were spent at the Department of Biochemistry, University of Wales in Cardiff where the fatty acid biosynthetic mechanisms of an EPA-producing strain was investigated using 14C radioactive labelling techniques.
1. 78% of strains isolated are psychrotolerant; the highest percentage found for any environment to date.
2. Of the 4 strains examined, 2 possessed optimal growth temperatures of 7-8 degrees C; only 3-4 degrees C above the lowest optimal growth temperatures so far recorded.
3. Two isolates may represent new species. Characterisation is continuing.
4. Identification of a psychrophilic strain producing ~20% eicosapentaenoic acid (EPA, 20:5w3) of total fatty acids under present culture conditions; this level is similar to many marine algae. Identification of two strains producing docosahexaenoic acid (DHA, 22:6w3). Levels of EPA production were temperature and nutrient dependent. Bacteria with this capacity have been reported only once previously. The production of EPA and DHA by Antarctic bacteria may have commercial implications. Already expressions of interest have been received from several companies.
5. A novel n-C31:9 polyene was found in several strains. This is the first report of a hydrocarbon of this type. Full structural characterisation is continuing.
6. Radiolabelling investigations of an EPA-producing strain lent further evidence to the PUFA biosynthetic mechanism we have proposed. These studies have also revealed further unusual aspects of fatty acid metabolism in this strain. These results are still under interpretation.
Ice cores, bacterial strains and copies of data sets (hard and soft) are stored at the Department of Agricultural Science, University of Tasmania. Cores are frozen and cultures stored in freeze dried ampules and/or on agar slopes at 2 degrees C. Copies of lipid analysis data (soft) is also stored at the CSIRO Marine Laboratories.
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Start Date: 1991-11-17Stop Date: 1993-01-21
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