The mucus-dwelling bacteria previously isolated from the surface
of a freshwater fish species (Alburnus alburnus from Lake Mogan,
Ankara), were studied to discover their cobalt resistance. The minimum
inhibitory concentrations (MIC) were determined for a total of thirty six
bacterial isolates. The results of the resistance studies led us to design
experiments on adaptation to cobalt and subsequent memory retention.
Three selected isolates were exposed to an inhibitory cobalt
concentration as a mixed culture and individually. The delayed
formation of colonies along with competitive exclusion of one of the
isolates in the mixed culture were recorded. The delay for colony
formation was followed up for liquid culture conditions. After some of
our isolates acclimated to cobalt and started to exhibit constant time of
growth period, it is assumed that they were adapted. We regarded
adaptation as a result of memory formation. Next, we did a further study
to find out how long this memory could be retained via serial multiple
passages in cobalt free medium. We expressed our observations
quantitatively by measuring the growth by using spectrophotometer and
by performing viable counts. Interestingly, where there was a high CFU,
the photometric values were very low. We interpreted the finding such
that the presence of cobalt above tolerance limits were causing size
reduction in the cells. So that their presence was underestimated by
optic devices in visible range. Our study hinted that freshwater bacteria
was adapting cobalt in a memory based mechanism and able to retain
this memory for some time.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12612824/index.pdf |
| Date | 01 December 2010 |
| Creators | Citir, Gozde |
| Contributors | Gozen, Ayse Gul |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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