Other Potential Applications
Moderately halophilic bacteria may have numerous additional potential uses in biotechnology, yet to be exploited. (i) It has been claimed that moderate halophiles may be used to remove phosphate from saline environments, as a cheaper alternative to chemical approaches (275). (ii) Moderate halophiles could be used in the recovery of hypersaline waste brines derived from the olive oil industry and leather- or fur-curing processes. (iii) They may be screened for the production of bioactive compounds such as antibiotics. (iv) Biological surfactants derived from moderate halophiles may have a variety of applications in industry. Thus, Yakimov et al. (369) recently isolated a moderate halophile which synthesizes a novel glycolipid belonging to a powerful novel class of biosurfactants. The bacterium (strain MM1, a member of the Halomonadaceae) was isolated from saline water and sediment samples by enrichment on n-hexadecane. The purified surfactant is a powerful surface-active agent, showing a strong positive effect on chlorinated biphenyl degradation, probably due to the solubilization of these compounds in water. (v) New restriction endonucleases and other enzymes for molecular biological studies are expected to be present in microorganisms from hypersaline habitats and will be discovered and exploited. (vi) Many moderate halophiles produce orange or pink colonies, probably due to the production of carotenoids as a protective mechanisms against photooxidation processes. Carotenoids have major applications in the food industry as food-coloring agents and as additives in health food products. Therefore, investigations of the utilization of moderate halophiles as producers of carotenoids could be of great interest.
Finally, we may note that in the last few years, considerable economic effort has been made to facilitate the exploitation of the potentialities of extremophilic microorganisms such as moderate halophiles. Thus, in Europe, a consortium of 39 teams funded by the BIOTECH-Programme of the European Commission has recently finished a 3-year project aimed at isolating and/or selecting the extremophiles with the best potential for industry. In early 1997, a new project was initiated to utilize these microbes as cell factories for the production of commercially interesting compounds. It may be expected that the moderately halophilic bacteria will shortly be used routinely in biotechnology as their astonishing properties are increasingly exploited.