Microbial Processes in the Deep Ocean Ecosystem - Term Paper Example

 Microbial processes in the deep ocean ecosystem Introduction Today our knowledge of the oceans is only limited to those areas where the sun penetrates and involves only a certain pressure levels. However, this would include only 1% of the oceans, and with greater depths where the sea pressure would be high, the sun penetrates only to a depth of a few hundreds of meters. It is at this level where the microbial life comes alive and microbial ecosystems function in a dark and cold environment. With the advent of new technology to access the deep sea areas, the microbial processes of the aphotic pelagic oceans, ocean crusts, hydrothermal vents, etc have increased. There are several bio-geo-chemical-thermal cycles which are occurring in the oceans and which are not known to man. These processes in the dark are changing the systems of the earth. With newer tools for conducting research of this biosphere and a greater understanding of the life and processes of the deep ocean scientist may be able to harvest the use of these (Orcutt, 2011). Macrorganism and microorganisms have an impact on the environment. Macrorganism have an indirect influence and often depend on the microbial processes. Microorganisms have a strong influence on the ecology they are present within. They can catalyze several reactions that can affect the properties of water and various sediments in water. Several substances can dissolve in water and several substances can be precipitated by using microorganism through a process of oxidation of organic matter to carbon dioxide. In the deep sea areas, the temperature of water is very low and microorganisms are able to catalyze the reaction. Many of the toxic organisms actually released from human activity may enter into the deep marine environment and microorganism in the deep sea can affect the fate and mobility of these compounds. Over the last 10 years, using advanced technological tools, the deep sea atmosphere has been studied, and a diverse and rich environment containing communities of organisms have been identified. These organisms cannot survive on the earth’s surface. Many of the terrestrial organisms have a strong influence on the biological and geochemical phenomenon, and with a rich and diverse microbial community at the deep level there would be huge potentials of these microorganisms which are not known to man today. Many of the organic and inorganic processes that occur at the geochemical levels can be controlled by these microorganisms (Lovley, 1995). Today geochemists are closely studying the redox reactions and bioturbation and bioirrigation. Many of the sedimentological methods are using molecular diffusion techniques, particulate transported methods and various other processes that occur at the marine levels. Many of the microbial processes are controlled by a feedback mechanism such that one organism influences the functioning of the other. The biotic factors are high in areas having high densities of fauna and in areas where the influence from dense human populations is less. Several coastal areas have dense human populations and the effect of the marine organisms is such that the species diversity is lost. The abiotic factors are stronger and the interaction between biotic organisms is reduced (American Geophysical Union, 2010). In this paper, we study the environment of the deep sea atmosphere, identify potential uses of the same and determine ways and means by which these resources can be used conservatively to the benefit of mankind without much destruction of the environment. Body Deep sea is usually used to refer to the area which is hundreds to thousands of meters below the surface of the ocean. However, scientists are also interested in studying sediments and life-forms that exist even at 10 meters below sea level. In any water flow system, classification can be done into 3 types mainly local, intermediate and regional. The local system recharges at a topographical high and would discharge at a topographical low. The rates of recharge and flow would be high. Intermediate flow systems are separated out by several topographical highs. The rate of recharge and the water levels do not react to the individual precipitation levels. Regional flow systems recharge at the divide and recharge at the basin bottom. In the deep subsurface environment, intermediate and regional systems are included. Because of the typical spore spaces which are very minute, the microorganism is the only organisms that occupy the spaces between the pore spaces. There is a good likelihood that microorganisms that are found in the deep subsurface would be similar to those that are found in the surface sedimentation. As light is not present in the deep ocean, microorganisms are not able to use the process of photosynthesis for producing food. Hence, the microbial life would depend on various food sources that are present in the sediments or are present in a dissolved form in the recharge water. Some of the energy sources that may be present include organic matter, reduced substances such as Manganese, Ammonium, sulfide, and Iron. These substances can be oxides to produce energy. The organism obtains energy by a complex process of transfer of electrons. Finally, in the environment one electron is transferred to an electron acceptor in the environment and may include Manganese, Iron, Carbon dioxide, etc (Lovley, 1995). Yayanos was able to obtain microorganisms that thrived at a level of 10500 meters under various conditions including 100 MPA, 2 degrees C and in some of the hydrothermal vents the temperature may be as high as 400 degrees C. The organisms were able to survive at greater than 40 Mpa for temperatures at 100 degrees C and in such circumstances there are also known as ‘extremophiles’. As the oceans get deeper, the microorganisms have to produce more and more specialized characteristics in order to survive in the hostile environment existing there. Organisms that are able live in a high pressure environment are known as barophiles. It was in the year 1972 that the first barophiles were identified and they could tolerate a pressure of 40 Mpa and more. On the other hand, barotolerant organisms are able to tolerate a pressure of below 40 Mpa, and are also able to grow well on the surface of the earth. There are chances that in the deep oceans, the living conditions may be stable over billions of years, such that ancient life-forms would still survive. Hence, the microorganisms that are present in the deep seas are definite clues of the evolution and origin of life (Yayanos, 1988). Kato et al conducted several studies on experimentation with barophiles. He used pressure greater than 50 Mpa and two temperatures of 10 degrees C and 15 degrees C. He found that the growth at 15 degrees C was much better than at 10 degrees C. Proteobacteria 7 subgroup was the group most of the barophilic and barotolerant organisms belonged. Some of the barophilic strains include DB5501, B6101, DB6705, DB6906, DB172F, and Shewanella sp. PT99. Some of the moderately barophilic strains include DSS12 and Shewanella benthica, Shewanella sp. SC2A, Photobacterium sp. SS9, S. hanedai, DSK1 and DSJ4. Using unmanned technology, samples of the water was obtained from the Marina Trench at a depth of 10,000 meters. Using PCR amplification techniques there were 2 kind of bacterial 168 RNA’s and these were closely related to the Pseudomonas species. However, they developed special characteristics to adapt to the deep sea pressure and the ocean coldness (Kato, 1996). When the bacteria obtained from the mud samples at the Marina trench and brought to the laboratory, they were grown on sterile marine broth consisting of marine agar (half-strength nutrient agar plates). Modified agar plates consisting of 1% starch, 1% skimmed milk, 0.2w/v Sodium Chloride and a pH of 3, 7 & 10 were used to cultivate the organisms. The agar plates were cultivated at 100MPa and a temperature of 4 to 75 degrees C for about 1 to 4 weeks. The bacteria that were formed as CFU’s and were obtained from a depth of 10,000 meters included alkaliphiles (that grew at the pH of above 9), barophiles, thermophiles (that grew at temperate 55-75 degree), psychrophiles, halophiles, non-extremophiles and acidophiles (that grew at a pH of below 3) (Hiroshi, 1998). At a depth of 2500 to 6500 meters, organisms that were barophilic or barotolerant but were also psychrophilic in nature were noticed. Psychrophilic refers to the inability of the organism to grow under conditions above 20 degree C. DB6705 was one such organism that was able to grow at 0.1 MPa to 4 degree C. When the pressure is increased, this organism was able to grow to a slightly higher temperature. DB21MT-2 can grow to a pressure of 80 MPa to 100 Mpa (Hiroshi, 1998). Microorganisms that are able to grow under higher temperature (above 75 degree C) are known as thermophiles and have been obtained from even terrestrial locations such as hot water geysers and marine solfataras. Two organisms that have been isolated that have been obtained at a depth of 1400 meters is Thermococcus profundus and Pyrococcus horikoshii (from the Mid-Okinawa Trough). To ensure that the bacteria are adequately protected, they develop highly thermostable proteins (such as an enzyme SDS-resistant protease, which can ensure resistance of the protein even in boiling hot water). Growth between 30-45 MPa was good, but at pressures above 60MPa, the growth was slower. Under high pressure, the cell stability was mainly ensured by bacterial transformation into the stationary stage rather than the growth phase. T. peptonophilus is also barophilic in nature, and can survive at 85 degrees C at 30Mpa or 90 degrees C at 45 Mpa. P. horikoshii can survive to 95 degrees C at 15 Mpa. Thus it can be seen that many of the thermophilic organisms exhibit barophilic characteristics between the relatiuonship of temperature and pressure. Many of the deep-sea organisms could also be exhibiting similar characteristic (Hiroshi, 1998). In the Eel River Basin located 30 kilometers off the coast of California, the natural conditions at the deep sea include seepage of methane gas and many of the deep sea anaerobic organisms thrive in these conditions. The bacteria consist of enzymes that are able to reduce sulfate to sulfide in order to produce energy. An Archea species, which is a non-bacterial organism, uses the process of methane oxidation in order to produce energy. These two organisms live in a symbiotic relationship with one another in the form of a conglomerate. The Archea species actively fixes nitrogen for the bacteria. Usually these organisms prefer environments that have lower nitrogen content (Dekas, 2009). The presence of viruses would vary in the deep oceans and may be high in the hydrothermal vent regions. It cannot be understood whether the bacteria and Archaea (prokaryotes) are susceptible to viral infections in deep oceans. However, scientists found that as a depth of the oceans increases, the number of viruses will not decrease as much as the number of prokaryotes would decrease. Hence, apparently, the concentration of viruses is higher in the deeper oceans (Nagata, 2010). Conclusion Rivkin proposed that in spite of the temperatures being low and the growth rates of the bacteria in the deep oceans depressed, they could in fact be an important connection in the food chain, that help the primary organisms in the food chain to grow and develop (such as dissolved carbon content for the phyloplankton). Rivkin also pointed that a significant portion of the global marine production occurs at the deep ocean levels. Temperature and pressure may be regulators of bacterial growth and activity, but they are not the only regulators. The dissolved organic content in the deep ocean is high and hence bacteria, viruses and algae would thrive (Rivkin, 1996). Some of the limiting factors for the deep ocean environment includes iron (found in the Subarctic and Antarctic regions and limits nutrient usage in a low chlorophyll environment), phosphorus (present in the North Pacific subtropical gyre which limits nitrogen fixation and is seen as a climate limitation) (Rivkin, 1996). There is a huge genetic wealth possessed by the microorganism that resides in the deep ocean. They have invaluable characteristics and today scientists are able to obtain such microorganisms through robot technology and study their properties in the laboratories. They could be harnessed in invaluable ways in the future, especially with academic and commercial ventures. Many unknown genes, proteins, enzymes, and compounds have been discovered. They could be many questions raised of the bioprospecting the deep-ocean life-forms (University of Toronto, 2007). However, there are also many threats arising especially associated with deep sea mining, oil extraction and pollution (presence of pollutants such as PCB’s, mercury and DDT) of the deep oceans. Many of the geothermal locations undersea have been stable over billions of years, and hence ancient life-forms have been preserved. These life-forms have been very sensitive to any changes in the ocean environment, and hence human activity such as pollution, deep sea oil extraction, and mining, can destroy these life-forms. The genetic wealth of the deep oceans is often known as ‘blue gold’. The deep sea product market is estimated to be around $2.4 billion in the year 2002, and includes several products including:- Anti-cancer drugs Antibiotics Anti-viral drugs DNA polymerases (for PCR reactions offering higher thermo-stability) Venuceane (a skin protection medication that contains a radical-scavenging enzyme and was originally obtained from an extremophile found in the deep seas) (Ruth, 2006). References American Geophysical Union (2005). Interactions between macro- and microorganisms in marine sediments, AGU Press, USA. http://books.google.co.in/books?id=qMY-kr6l73YC&pg=PA299&lpg=PA299&dq=Microbial+processes+in+the+deep+ocean+ecosystem&source=bl&ots=ebcgKZxtpm&sig=I_4FcgKYhVXYqkBElW-90jfjcrg&hl=en&ei=pknUToGVNsjlrAf8h4mJDg&sa=X&oi=book_result&ct=result&resnum=6&ved=0CFAQ6AEwBQ#v=onepage&q=Microbial%20processes%20in%20the%20deep%20ocean%20ecosystem&f=false Dekas, A. E., Poretsky, R. S., & Orphan, V. J. (2009). ‘Deep-Sea Archaea Fix and Share Nitrogen in Methane-Consuming Microbial Consortia’. Science Daily, 326 (5951): 422 DOI: 10.1126/science.1178223. http://www.sciencedaily.com/releases/2009/10/091016094047.htm Hirokoshi, K. (1998). ‘Barophiles: deep-sea microorganisms adapted to an extreme Environment.’ Current Opinion in Microbiology, 1:291-295. http://www.dms.ufsc.br/mip7013/arquivos/2896_Barophiles.pdf Kato, C., Tamegai, H., Ikegami, A. Et al (1996). ‘Open reading frame 3 of the barotolerant bacterium strain DSS12 is complementary with cydD in Escherichia co/i: cydD functions are required for cell stability at high pressure’. J Biochem, 120:301-305. Lovely, D. R. & Chapelle, F. H. (1995). ‘Deep Surface Microbial Process.’ Reviews of Geophysics, 33(3): 365-381. http://www.geobacter.org/publication-files/Rev_Geophys_1995_Aug.pdf Orcutt, B. N., Sylvan, J. B., Knab, N. J. Et al (2011). ‘Microbial Ecology of the Dark Ocean above, at, and below the Seafloor.’ Microbiol. Mol. Biol. Rev., 75(2): 361-422. http://mmbr.asm.org/content/75/2/361.abstract Nagata, T. (2010). ‘Emerging concepts on microbial processes in the bathypelagic ocean – ecology, biogeochemistry, and genomics.’ Deep-Sea Research II, 57, 1519–1536. http://yyy.rsmas.miami.edu/groups/biogeochem/Hansell%20pdfs/77%20Hansell.pdf Rivkin, R. B., Anderson, M. R., & Lajzerowicz, C. (1996), ‘Microbial processes in cold oceans. I. Relationship between temperature and bacterial growth rate.’ Aquat Microb Ecol, 10: 243-254. http://www.int-res.com/articles/ame/10/a010p243.pdf Ruth, L. (2006). ‘Gambling in the deep sea.’ EMBO reports, 7, 17 – 21. http://www.nature.com/embor/journal/v7/n1/full/7400609.html University of Toronto (2007, May 17). Deep-sea Mining May Pose Serious Threat To Fragile Marine Ecosystems, According To Study. ScienceDaily. Retrieved December 1, 2011, from http://www.sciencedaily.com­ /releases/2007/05/070517142603.htm Yayanos, A. 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