Sristi Raj Rai, Amity University Kolkata
You probably know the fate of Jack & Rose – famous fictional characters featured in the movie ‘Titanic’, but have you ever wondered about what happened to the ‘unsinkable ship’ after it got swallowed into the near-freezing water of the Northern Atlantic ocean. The passenger and mail steamship, Royal Mail Ship (RMS) Titanic – 883 ft long, 92 ft wide that displaces 2240 pounds of water got wrecked on its voyage from Southampton, England to New York City and hit the ocean bed in the early morning hours of April 15, 1912. Almost 2 hrs after the ship struck the iceberg, 1,517 out of 2,000 passengers & crew couldn’t find a refugee on a lifeboat and became the victim of hypothermia.
History & Discoveries –
Originally made up of 50,000 tons of iron, the ship dramatically cracked into the stern and the bow, lying some 2,000 ft apart in opposite directions. After 73 years in 1985, about two miles below the ocean surface and some 329 miles southeast of Newfoundland, Canada, the same got discovered in a progressively deteriorating shape by oceanographer Robert Ballard. Redemption was granted to the humongous ship by the sea as it has been housing lively marine life-forms making it an underwater scientific laboratory fueling the growth of marine science/biology aiming to explore the sea. One of the marine microorganism species invisible to naked eye dwelling was Halomonas titanicae isolated by Cristina Sánchez-Porro et al. in 2010. This extremophile lives inside icicle-like growths of rust, called rusticles (a weaker form of the metal), giving the ship a melting appearance.
Degradation of titanic by halomonas titanicae –
The porous rusticles that were obtained from the hull using the articulated arm of the Mir 2 robotic submersible during the Akademic Keldysh expedition in 1991, which will eventually disintegrate into a pile of fine powder in the upcoming 15-20 years of RMS Titanic as per researchers’ prediction. It is depressing to watch history’s icon eventually getting consumed by H. titanicae feeding on the iron hull and recycling the nutrients into the ocean ecosystem while mollusks are gobbling down the wood left on the deck. Though in 2012, Ballard recommended painting the remaining relics with anti-fouling paint to slow down the degradation process in order to retain it as long as possible before it vanishes like it never existed below, but that project has not come to pass.
What do you think about the current marine environment of the ship?
Lack of light and tremendous pressure makes any sphere inhospitable for most life-forms but DNA technology revealed that the rusticles are composed of 27 different strains of the bacteria. They still don’t know whether the species was living on the ship before it sank or not. These new metal-munching bacteria are one of them that can adhere to the steel surfaces forming knob-like mounds of corrosion. Though shipwrecks’ dating back to 14th Century BC still exists, the reason being that the microbes colonizing the remnants were feeding on the wood (cellulose, hemicelluloses, or lignin), the material with which the ships were made up of back then, formed a biofilm which acted as a shield against seawater. As these iron-loving species even at low temperatures hold the capability to recycle iron from the steel structures, they can be useful in the disposal of old naval and merchant ships and oil rigs. There might be more such species that can help us investigate corrosive processes.
Are you aware of the other powers that these Halomonas bacteria possess?
Not only that, these bacteria have inherited the power to survive in salt marshes on Earth with varying salinity of water due to evaporation. Changes in salt concentration can be harmful to any living species due to the acting osmosis. But salt-loving Halomonas bacteria have evolved to an extent that no other species have and adapted to such an environment, living there comfortably. Ectoine (compatible solute moiety produced) is the natural carboxylic acid used by these bacteria to counterbalance their osmotic pressure identified by Joe Zaccai, who was a part of an international team of scientists.
Yang Yo and his group recently uncovered Halomonas titanicae SM1922’s one more astonishing trick of utilizing and recycling, not one, not two, but seven D-amino acids (DAAs – an essential dissolved organic component and sole N-source of the oceanic pool) by various enzymatic pathways. The motility of these gram-negative bacteria promotes rapid adherence with greater surface densities to hexadecane oil droplets compared to non-motile H. titanicae (flagellar motion arrested via a proton uncoupler).
Narendra K. Dewangan and Jacinta C. Conrad stabilized the above microbial system by the addition of dioctyl sodium sulfosuccinate (DOSS – anionic surfactant reduces oil-artificial seawater interfacial tension). Therefore, Halomonas titanicae, a microscopic heterotrophic, aerobic species that derives its energy from rusticles can turn the gigantic ‘RMS Titanic’ into a pile of dust and also has the means to thrive in several extreme climatic conditions. Current researches are focused on unlocking the full potential that the species possesses and also acting as an exceptional bio-remediation agent.
Also read: How much plastic are you eating? New study revealed
SOURCES –
- Sánchez-Porro, C., Kaur, B., Mann, H. and Ventosa, A., 2010. Halomonas titanicae sp. nov., a halophilic bacterium isolated from the RMS Titanic. International Journal of Systematic and Evolutionary Microbiology, 60(12), pp.2768-2774. https://doi.org/10.1099/ijs.0.020628-0
- Yu Y, Yang J, Zheng L-Y, Sheng Q, Li C-Y, Wang M, Zhang X-Y, McMinn A, Zhang Y-Z, Song X-Y and Chen X-L (2020) Diversity of D-Amino Acid Utilizing Bacteria From Kongsfjorden, Arctic and the Metabolic Pathways for Seven D-Amino Acids. Front. Microbiol. 10:2983. DOI: 10.3389/fmicb.2019.02983
- Dewangan, Narendra & Conrad, Jacinta (2020). Bacterial Motility Enhances Adhesion to Oil Droplets. Soft Matter. DOI: 16.10.1039/D0SM00944J.
- Fox-Skelly, J., 2020. The Wreck Of The Titanic Is Being Eaten And May Soon Vanish. [online] Bbc.com. Available at: <http://www.bbc.com/earth/story/20170310-the-wreck-of-the-titanic-is-being-eaten-and-may-soon-vanish> [Accessed 30 November 2020].
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