Question

What is the most effective way to culture Halobacterium noricense that colonize The Great Salt Lake in Utah? Explain how the conditions and culture media you choose will meet the nutritional and environmental needs of the microorganism. (Is there a particular temperature you should use? Is CO2 needed? What medium would be best?)

Answer 1

H. Noricense can be isolated from environments with high salinity such as the Dead Sea and the Great Salt Lake in Utah. Members of the Halobacterium genus are excellent model organisms for DNA replication and transcription due to the stability of their proteins and polymerases when exposed to high temperatures.Halotolerant or halophilic (Archaeabacteria) microorganisms can be found in salted and ripening fish products that are not affected by salt. They can be moderate or extremely halophilic bacteria. The extremely halophilic bacteria require between 15-30% of NaCl for growth. The extremely halophilic archaeobacteria may be selectively isolated in different media. The aim of this work was to determine the effectiveness of the Salt-Agar-Milk medium, a medium modified in our laboratory through the addition of MgSO4 and KCl - named SAMm, and its effect on the bacterial growth by means of comparison with other media, with and without milk, determining time of incubation and counting. Two samples of salted fish from local fish salting factories and two laboratory strains were used. The factory samples were matured anchovy and anchovy fillets in oil, and the laboratory strains were: Haloarcula spp. (proteolytic) and Halococcus spp. (non-proteolytic). The following media were alternatively used for the isolation of extremely halophilic bacteria: IRAM; Formulation of Gibbons and collaborators, Cod Milk agar, and SAMm. IRAM and Gibbons were also used enriched with milk. In the SAMm medium, there were obtained count values similar or higher than the ones of the traditional media; besides the simplicity of its elaboration, the possibility to obtain positive results two or three days earlier also added to its benefit. Consequently, it can be considered an alternative to the media traditionally used for the studied halophilic bacteria.

Is there a particular temperature you should use?

Answer : optimal growth temperatures forHalobacterium noricense is 28–50 °C

Is CO2 needed?

Answer : H. noricense uses aerobic respiration in most environments, except when exposed to L-arginine or nitrate. In these cases, it can function as a facultative anaerobe. So that CO2 is not mandatory.

What medium would be best?

Halobacterium can be adapted to growth in deuterated media and is an ideal host for amino acid-specific labeling since it possesses multiple auxotrophies for amino acids.Even though highly salted medias are also used.