| Popis: |
Halophilic and halotolerant microorganisms are known to have numerous potential biotechnological applications, but to date, they have been largely underexploited in comparison to other extremophiles. The overall aim of the research presented within this thesis was to further investigate some of the biotechnologically useful products and processes that halophilic and halotolerant microorganisms are known to possess. Firstly, halotolerant bacterial isolates from a polluted marine environment were shown to be extremely tolerant to l-alkyl-3-methylimidazolium chloride ionic liquids, with much greater levels of tolerance to these compounds than has previously been reported for other microorganisms, and in addition, some of the isolates had the ability to biodegrade these compounds. This indicates that bacteria from the marine environment, due to their adaptation to salinity and the presence of hydrocarbons within this environment, would be highly suited to biological processes involving exposure to ionic liquids. Kilroot salt mine was investigated as a source of halophilic microorganisms as its culturable microbiome has never before been profiled; exploration of this environment indicated a great culturable biodiversity of both bacteria and archaea. The haloarchaeal isolates were shown to form biofilms, which enhanced the tolerance of the haloarchaea to an antimicrobial challenge. This is the first time this protective function ofhaloarchaeal biofilms has been demonstrated. Screening the isolates against a panel of antibiotics revealed an unexpectedly high level of natural resistance, indicating the presence of antimicrobial-producing microorganisms in the salt mine environment. To examine this further, organic extracts of each isolate from the mine were tested against a range of pathogenic bacteria, with approximately 40% displaying antimicrobial activities. One activity of particular interest was that of a haloarchaeal isolate of the genus Halorubrum, which exhibited both in vitro and in vivo antimicrobial and antibiofilm activity against P. aeruginosa. Whole genome sequence analysis of this isolate revealed further biotechnologically-important functions which provides numerous opportunities for additional studies, and reinforces the biotechnological potential of these organisms that is waiting to be exploited. |
