Question

Barophilic Prokaryotes
A. Grow slowly in highly alkaline frozen lakes at high altitude
B. Occur in water containing a high concentration of barium hydroxide
C. Grow and multiply in very deep marine sediment
D. Readily grow and divide in seawater enriched in any soluble salt of barium

Answer 1

Barophilic prokaryotes grow and multiply in very deep marine sediments. A barophilic prokaryote, also generally defined as a barophile, is a type of organism which occurs and exists at high-pressure zones, like deep-sea bacteria and archaebacteria.

Complete answer:
-Two strains of obligately barophilic bacteria were isolated from a sample of the world’s deepest sediment, which was obtained by the unmanned deep-sea submersible Kaiko in the Mariana Trench, Challenger Deep, at a depth of 10,898 m. From the results of phylogenetic analysis based on 16S rRNA gene sequences, DNA-DNA relatedness study, and analysis of the fatty acid composition, the first strain (DB21MT-2) appears to be most highly similar to Shewanella benthic and close relatives, and the second strain (DB21MT-5) appears to be closely related to the genus Moritella.
-The optimal pressure conditions for the growth of these isolates were 70 MPa for strain DB21MT-2 and 80 MPa for strain DB21MT-5, and no growth was detected at pressures of less than 50 MPa with either strain. This is the first evidence of the existence of an extreme-barophile bacterium of the genus Moritella isolated from the deep-sea environment. To investigate the environment and the biology of the deep-sea world, several manned and unmanned deep-sea submersibles have been constructed.
The newly constructed unmanned submersible Kaiko, which means trench in Japanese and which is operated by the Japan Marine Science and Technology Center, is the most capable of all, with an ability to submerge to the world’s deepest sea bottom depth of 11,000 m.
-It seems likely that this was the first time sediment samples have been recovered from the world’s deepest point without any microbiological contamination derived from overlying waters. We have reported the molecular analysis of this sediment and the sequences of pressure-regulated genes found in DNA extracted from these samples. These findings suggested that deep-sea-adapted barophilic bacteria are present in the sediment.
-Barophilic bacteria were isolated according to the procedure reported previously. For single-colony isolation, the cultures were incubated under a pressure of 100 MPa in plastic bags. Growth of the isolates under conditions of 0.1 to 100 MPa at 10°C in pressure vessels.
-Six obligately barophilic strains that we’re able to grow well at 100 MPa and which were not able to grow at atmospheric pressure were isolated from the Mariana Trench sediment.
The first obligately barophilic strain isolated from the Mariana Trench was strain MT41 (22), which was unable to grow at pressures of less than 50 MPa, and its optimal pressure for growth was approximately 100 MPa. Thus, this strain is also an extreme-barophile bacterium. It is not related to the genus Shinwell or Moritella but is closely related to the genus Colwellia.
Hence, the correct answer is option C.

Note: Extremely barophilic bacteria, which we defined as bacteria that are unable to grow at pressures of less than 50 MPa but that are able to grow well at 100 MPa, was isolated from sediment obtained by means of the unmanned submersible Kaiko system from the world’s deepest ocean bottom, the Mariana Trench, Challenger Deep, at a depth of 10,898 m.