Photosynthesis Deep within Ocean Waters - Essay Example

Deep sea life: Scientists have done numerous researches to study the properties and benefits of micro organisms that are widely distributed throughout the world. They have discovered wonders by studying the properties of these microbes. Micro organisms are everywhere around the world from soil to deep sea oceans, in air, in foods, in the atmosphere surrounding us and even in such places where existence of life is impossible. One such example is the discovery of bacteria in the hot environment of lava. These little organisms find a way to live in such places by adjusting accordingly and are highly resistant. The existence of microbial life in deep sea was discovered ages ago. They have been sorted out into different categories depending upon their properties. The sea bed is a diverse environment which is rich in nutrients. The organic material settles down as sediments at the bottom which comes from dead plants and animals and it is a source of energy for microbial life. Therefore in these sites most particularly the sea floor where nutrients are present diverse microbial communities exists. There are micro organisms which can survive even in energy depleted conditions that is when no or limited amount of nutrients are present. Condition in deep sea is very critical as energy is most depleted there. It is difficult to understand how micro organisms survive in these conditions. (Feast and famine microbial life in the deep sea bed, 1 October 2007). Micro organisms can live in places where there is no light and an example of such place is deep sea. Sunlight cannot penetrate deep into the sea and the existence of microbial life in the dark zone of sea floor is yet to be understood. Researchers have dedicated their studies to explore life in the darkness of deep sea. Recent discovery of microbial communities in deep sea hot spring vents gives the idea that the earliest existence of life might have occurred in the deep sea in the absence of light. Before, this discovery it was assumed that light is necessary to survive as it is the primary source of energy but, now it is known that life that exists in deep sea vents survive on thermal and chemical energy provided by the vent which means that light is not necessary for survival. (Deep sea vent communities: Did life originate in the abyss?) Scientific studies reveals how organisms manage to survive in hydrothermal vents. When cold sea water mixes with the heat of hydrothermal vents it leads to the formation of organic compounds which is a source of nutrient for the organisms. The presence of vents in oceans also helps in maintaining the temperature and chemical balance of oceans and is a source of many renewable resources. Hydrothermal circulation occurs when sea water penetrates deep into the ocean where it gets heated and then reacts with rocks and rises to the sea floor. This hydrothermal circulation plays an important role in removing and adding up different compounds and in this way maintains the composition of sea water. Hydrothermal circulation also helps in recycling the water of oceans through hydrothermal vents. (Deep sea vent communities: Did life originate in the abyss?) The environment of hydrothermal vents is harsh for survival of life. The pitch darkness of vents, poisonous gases, presence of heavy metals, extreme acidity and enormous pressure makes the existence of life almost impossible. Yet, microbial communities exist at hydrothermal vents. In deep sea there is no light and when there is no light the presence of solar energy is out of question. All forms of light require light directly or indirectly as a source of energy but, life in deep sea is light independent. In this case organisms use geothermal energy as their energy source to carry out their life sustaining processes. Such organisms use inorganic chemicals derived from rocks and from sea water where nutrient is abundantly available in soluble form and utilize CO2 as their sole source of carbon. (Jean, Windsor, Between a rock and a hard place, Wonder quest) As hydrothermal vents are present in deep sea there is no chance of sunlight to reach this deep and in the absence of light the process of photosynthesis does not occur. So, plants are unable to survive in such conditions as a result of which hydrothermal vents serves as home for animals. Animal’s forms symbiotic association with chemosynthetic microbes present in these vents which means that they depend on microbes for their survival. Chemosynthetic bacteria utilize sulfur from the fluid of the vent and convert it into energy through chemosynthesis. Larger animals then feed on these bacteria thus the chemosynthetic bacteria are the base of food chain at hydrothermal vents. (Habitats: Hydrothermal vent- Characteristics) Hydrothermal vents supports enormous microbial communities compared with other areas of deep oceans. One of the sources of energy comes from oxidation reduction reactions which supports chemosynthesis. The hydrosphere gets oxidized by electron acceptors like O2, SO3 and NO3. On the other hand rocks present at the bottom of ocean are reduced because of ferrous ions. Chemical energy is present in abundance in deep sea now, it depends on the microbial communities how they adapt themselves to utilize it. As temperature is high in hydrothermal vents micro organisms present here must be able to resist high temperature. Organisms that are of particular interest are hyperthermophiles. Hyperthermophiles are organisms that have the ability to grow at 90’C or above so, they can easily survive the harsh environment of vents. Example of hyperthemophile is Archaebacteria; enzymes of hyperthermophiles are highly stable which helps them to resist such high temperatures. (Robert, Michael and Alissa, 21 November 2000, Life in extreme environments: Hydrothermal vents). Micro organisms present in hydrothermal vents are the only known organisms on earth that derives energy from chemicals rather than sunlight. The food chain on land is based on photosynthesis whereas in deep sea it depends on chemosynthesis, a process by which organisms obtain their food from chemicals. Bacteria in hydrothermal vents play key role in converting toxic chemicals into food and energy which is utilized by other organisms of vents. This creates a symbiotic association between the microbes and other animals such as clams and tubeworms. These animals either directly feed on bacteria or sometimes may even harbor them in their bodies so, that they can make food for them. These little organisms can be used in industries because they possess enzymes that have the ability to resist high temperature and pressure and can be used for degradation purpose. (Chemosynthesis) Different studies have revealed how micro organisms capture carbon in the deepest oceans where there is no light. The source of carbon is carbon dioxide that is fixed in oceans every year. Micro organisms need carbon dioxide to carry out their metabolic reactions which enables them to survive. As discussed earlier Archaebacteria (single celled organism) has the ability to resist the harsh conditions of the vents so, it can be assumed that Archaebacteria is responsible for carbon fixation in the darkness of the deep sea. It is observed from studies that bacteria other than Archae also help in fixing carbon. (Department of energy DOE Joint genome institute JGI, 1 September 2011, up from the depths: How bacteria capture carbon in the twilight zone). Life in deep sea is different from life on the surface. Oceans serve as a home for some of the most diverse population on this planet. There is a variety of organisms living under water ranging from large to small animals to tiny creatures like micro organisms. Ocean is divided into five zones by the oceanographers depending upon the penetration of light. Epipelagic or sunlit zone: This is the topmost zone of the ocean where sunlight directly reaches and favors the growth of plants. Mesopelagic or twilight zone: It is just beneath the sunlight zone where little light penetrates so; plants are not present in this zone as they require sunlight for their growth. Bathypelagic or midnight zone: This zone is present deep within the ocean where there is no chance for sunlight to penetrate. Only Animals live in this zone. Abyssal zone: It is the bottom layer of the ocean where there is pitch darkness. Temperature and pressure in this zone are extremely high. This is the zone where hydrothermal vents are present. Hadal zone: This zone is Approximately 20,000 feet below the surface. Plants are found only in the topmost layer whereas animal and other tiny creatures are present in all zones of ocean. As food is in bulk in the topmost layer therefore this zone is more alive than any other zone. (The living sea) In clear water sunlit zone could be very deep as sunlight could penetrate deep into the ocean but, in turbid water this penetration will be restricted to only 50 feet. Temperature also varies in all zones; due to the heat of sun temperature will naturally be high in sunlit zone however the deeper zones like abyssal and hadal zone are cooler comparatively. Food chain of the ocean is also dependent on sunlit zone as sunlight is easily available for plants to perform photosynthesis. As a result of photosynthesis sunlight and Carbon dioxide are converted into food (mainly carbohydrates) and Oxygen. 90% of the earth’s oxygen comes from oceans. Example of photosynthetic organisms in sunlit zone is algae and phytoplanktons. They are also known as primary producers or autotrophs that can make their own food. Other animals of the ocean are dependent for food on these primary producers. Most of the animals present in twilight zone have adapted themselves to live in the darkness; they have the ability to make their own light that is they are bioluminescent. This is an unusual way which helps them find food and also to escape from predators. They feed on algae or food that comes from the sunlit zone or they may eat each other. Some of the examples of animals in twilight zone include crabs, jelly fish, shrimp and many worms. (Sunlit Ocean) Photosynthesis in deep sea: All organism needs energy to survive and the primary source of energy is sunlight. Photosynthesis is a process by which sunlight is used to provide energy. It is carried out by many plants and some types of bacteria. In this process energy within the sunlight is converted into chemical energy. In plants and algae the process of photosynthesis occurs in chloroplasts that are present inside the cell. It is well known that photosynthesis is a beneficial process and is observed most commonly in plants and some types of algae and bacteria. Through this process molecular oxygen is released and carbon dioxide is removed from the atmosphere. It provides energy and reduced carbon required for the survival of life as well as oxygen which is then taken up by aerobic organisms. Photosynthesis widely effects earth’s atmosphere by reducing atmospheric carbon dioxide to carbohydrates. (John, Govindjee, the photosynthetic process). The process of photosynthesis involves two phases light phase and dark phase. Light phase involves a molecule called chlorophyll which captures light energy. As the name indicates in light phase light energy from sun is absorbed by the chlorophyll. The second phase that is the dark phase is also known as carbon fixation or Calvin cycle. In the presence of water the process of photosynthesis is very efficient because in this case both light and dark reactions occur simultaneously in same cell as a result of which more energy is produced. The reactions of photosynthesis in bacteria take place in cell membrane outside the nucleus whereas in eukaryotic organisms it occurs in chloroplasts. (Dr. David, How does photosynthesis occur?). Sunlight plays an important role in our life, all the food we eat and all the energy we use is provided by photosynthesis which increased the significance of this process. Photosynthetic bacteria can be divided into two group oxygenic photosynthetic bacteria and anoxygenic photosynthetic bacteria. Oxygenic photosynthetic bacteria: They use water as an electron donor and release oxygen as a byproduct. Photosynthetic mechanism is located in thylakoid membrane example is Cynobacteria. Anoxygenic photosynthetic bacteria: They utilize sulfur containing compounds as electron donor and do not release oxygen. In these bacteria photosynthetic reaction occurs in organelles called chlorosomes.Example includes the green sulfur and the purple sulfur bacteria. (Bacterial growth and microbial metabolism) Due to lack of light in the deep sea there is no chance that the process of photosynthesis will occur but, yet amazingly photosynthesis is taking place which have stunned the scientists. A microbe is discovered which uses dim light coming from hydrothermal vents to perform photosynthesis. Before this discovery nobody would have thought that photosynthesis can occur in absence of sunlight. These photosynthetic organisms belong to a group of organism called green sulfur bacteria. They use sulfur as electron donor and have no or extremely low oxygen requirements. Since the vents are rich in sulfur and do not have oxygen so, the condition is favorable for green sulfur bacteria to grow in these vents. (Naila Moreira, 28 June, Grow in the dark: bottom dwelling bacterium survives on geothermal glow). Green Sulfur Bacteria: First photosynthetic bacteria have been discovered in deep sea that carries out the process of photosynthesis in absence of sunlight. It is the green sulfur bacteria and it has significant importance in hydrothermal vents. This bacterium was found to live in the interface between the hot water of the vents and the cold sea water. Water sample collected from this area was analyzed and it revealed that bacteria can grow from the glow of the vents. Furthermore, DNA analysis was carried out which helped in the classification of this amazing bacteria and it happened to be a member of green sulfur bacteria family. In order to live these bacteria depends on photosynthesis. “These organisms are the champions of low light Photosynthesis.” (Robert Blankenship) Green sulfur bacteria have an efficient mechanism by which it captures any light that is present in its surrounding and transfer it to the particular area within the cell where photosynthesis occur. The discovery of green sulfur bacteria expanded the vision of thought that photosynthetic bacteria could be present anywhere on this planet. The phenomenon of photosynthesis is widely distributed and is not just limited to the surface of earth. The problem is we don’t yet know where to find them. (Scientists find deep sea photosynthetic bacterium, June 21 2005) Green sulfur bacteria are anaerobic in nature and oxidize sulfur compounds for their growth and reduce carbon dioxide to organic carbon. They are capable to perform photosynthesis in the presence of extremely low light which is why they can be isolated from hydrothermal vents where the only source of light is geothermal radiation. Photosynthesis with light energy occurs on the surface whereas, photosynthesis with little or no light occurs below the surface. Geothermal light made it possible for photosynthesis to occur in the deepest and darkest area and play an important role in increasing the biodiversity. Evidence of photosynthesis in deep sea also gives the possibility that photosynthesis might occur on planets that are far away from sun and who knows it might already be going on. It means that life exists on other planets as well. Some of the properties of green sulfur bacteria are: i: They are rod shaped anaerobes. ii: They can grow in light depleted conditions. iii: They possess chlorosomes (light harvesting structures). iv: They are gram negative. v: They are non motile they do not have flagella. vi: They have a light harvesting protein known as FMO (Fenna-Matthews-Olson). vii: They are resistant to toxins which helps them to survive in the variable environment of deep sea. viii: They require sulfur containing compounds for their growth. ix: They can fix carbon dioxide. x: They appear as straight or curved rods. (J. Thomas, 3 March 2005, An obligatory photosynthetic bacterial anaerobe from a deep sea hydrothermal vent). Most of the forms of green sulfur bacteria are green in color hence it is named as green sulfur bacteria. Most of them are found residing beneath purple sulfur bacterial layer. They persist in anaerobic conditions and uses elemental sulfur as electron donor. Green sulfur bacteria can be classified into four genera: Chlorobium, Prosthecohloris, Pelodictyon and Clathrochloris. The presence of chlorophyll in green sulfur bacteria makes them appear green. They are mainly found in marine water where there is plenty of sulfur containing compounds. They have the ability to resist extreme conditions like high temperature of hydrothermal vents. The chlorophyll present in green sulfur bacteria can absorb maximum radiations of variable wavelengths ranging from 450-800 nanometers. Green sulfur bacteria help to accumulate organic compounds in oceans and actively take part in sulfur cycle. Accumulation of organic compounds acts as a source of nutrients for other forms of life present in water. (Lars, Green sulfur bacteria, Biol/Cses 4684). Scientists discovered a member of green sulfur bacteria from a hot spring in New Zealand which was Chlorobium tepidum. It is believed that photosynthesis performed by green sulfur bacteria is different from that performed by other bacterial species or plants. In plants photosynthesis occurs in chloroplasts whereas, in green sulfur bacteria photosynthesis takes place in organelles called chlorosomes. It should also be noted that unlike plants green sulfur bacteria perform photosynthesis in fully anaerobic conditions whereas, plants require oxygen for photosynthesis. The mechanism to capture Carbon dioxide also differs in green sulfur bacteria and plants. Green sulfur bacteria uses the reductive tricarboxylic acid cycle (TCA) to obtain carbon dioxide whereas, plants use Calvin cycle for this purpose. Green sulfur bacteria have a unique mechanism of capturing dim light of hydrothermal vents. “Because of their unusual mechanism of harvesting and using the energy of light, The green sulfur bacteria are important to understanding the evolution and the mechanisms of both photosynthesis and cellular energy metabolism.’’ (Jonathan A. Eisen, an evolutionary biologist) Some scientists believe that green sulfur bacteria were the first organism to carry out photosynthesis on this earth since they have the ability to perform photosynthesis in absence of oxygen and when earth evolved there was very little oxygen. Gene sequencing of Chlorobium tepidum revealed the presence of genes that are important in photosynthesis. Further research is going on and scientists are trying to study the characteristics of this unusual group of micro organisms. (Science daily, July 8 2002, Genomic clues to the evolution of photosynthesis). Work cited: 1. Jorgensen, B. B., & Boetius, A. (October 01, 2007). 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University of Delaware College of Marine Studies and Sea Grant College Program. http://www.ceoe.udel.edu/deepsea/level-2/chemistry/chemo.html 7. The living sea, Oceans alive http://www.mos.org/oceans/life/index.html 8. Sunlit ocean http://www.enchantedlearning.com/biomes/ocean/sunlit/ 9. Scientists find deep sea photosynthetic bacterium, june 21 2005 http://www.redorbit.com/news/science/157333/scientists_find_deepsea_photosynthetic_bacterium 10. Soil microbiology, Lars juul http://filebox.vt.edu/users/chagedor/biol_4684/Microbes/greensul.html 11. The Institute For Genomic Research (2002, July 8). Genomic Clues To The Evolution Of Photosynthesis. ScienceDaily. Retrieved http://www.sciencedaily.com/releases/2002/07/020708082404.htm 12. Up from the depths: How bacteria capture carbon in the twilight zone, September 1, 2011 http://www.physorg.com/news/2011-09-depths-bacteria-capture-carbon-twilight.html 13. Singhal, G. S., & Singhal, G. S. (1999). Concepts in photobiology: Photosynthesis and photomorphogenesis. Boston: Kluwer Academic Publishers. http://www.life.illinois.edu/govindjee/paper/gov.html 14. How does photosynthesis occur http://www.ehow.com/how-does_5421333_photosynthesis-occur.html 15. Bacterial growth and microbial metabolism, Introduction to photosynthesis http://faculty.ccbcmd.edu/courses/bio141/lecguide/unit6/metabolism/photosyn/photo.html 16. Moreira, N. (January 01, 2005). Bottom-dwelling bacterium survives on geothermal glow. Science News, 167, 26, 405. http://www.phschool.com/science/science_news/articles/grow_in_dark.html Read More