The recent advancements made in petroleum microbiology - Term Paper Example

? Petroleum Microbiology Your Biology 11/08 How important are the recent advancements made in petroleum microbiology? Petroleum, in the twenty – first century, remains to be one of the most significant sources of fuel and energy. It is a complex blend or mixture of different types of hydrocarbons and organic compounds. It may sometimes also contain traces of transition metal complexes (called organometallo) like nickel and vanadium (Lerner, 2011). The compositions of petroleum, and thus its physical and chemical properties, vary from place to place, and from area to area. In the current scenario, the demand for petroleum and its by – products continues to rise. In an answer to them, science has come up with the use of microbiology during the extraction and purification of petroleum. The study of this use and application of microorganisms in the fuel industry is called petroleum microbiology (Encyclopedia, 2005). The most important experimental works in the field of petroleum microbiology have been done by Claude ZoBell (Lerner, 2011). His research, which extended for over 40 years (1930 – 1970), has proved that microorganisms, especially bacteria, play an important role in most of the vital processes related to petroleum, which include its formation, extraction and refining. The hydrocarbons and petroleum products have been termed as ‘substrates’ or ‘nutrients’ for microbes, which they need in order to carry out efficient metabolism. This feeding of bacteria and fungi is aided by the action of certain enzymes and is called, biodegradation (Hamme, 2003). Most of the hydrocarbons are broken down to release carbon dioxide, water, proteins and nucleic acids. The carbon dioxide escapes to the atmosphere while the rest of the products are used for cellular growth. Bacteria and fungi involved in biodegradation are highly specific in function, that is, not all bacteria can break down a specific hydrocarbon or organic compound. Pseudomonas and mycobacterium are examples of some degrading bacteria while examples of fungi include Candida (Van Hamme, 2003). With the advancement of biotechnology and microbiology, scientists have widened their understanding and developed better concepts of the metabolic processes related to microbial actions on petroleum (Van Hamme, 2003). The effects of the use of the hydrocarbons as substrates by the microorganisms involve alteration of cell surface membranes and mechanisms of both uptake and discharge. Similarly, the ability to study the behaviour of microbial organisms, in a petroleum rich environment at a molecular level has also been enhanced. Under the optimum conditions for the growth of these organisms, they have been treated with hydrocarbons, and transformed to take part in highly accelerated and bioreactor-based petroleum waste degradation processes, that are now being implemented (Atlas, 1995) (Van Hamme, 2003). In the modern world, petroleum microbiology is an important part of bioremediation which involves controlling oil pollution (Bronson, 1993). Bioremediation is the use of microorganisms to get rid of pollutants and harmful substances from the environment. Oil pollution is the result of seeping and spillage of oil from tankers into the sea, as well as intentional or deliberate discharge of oil products into the water sources. The huge spill of crude oil from a tanker near Alaska’s coast back in the 1980s practically showed the scientific world of the usefulness of biodegradation (Bronson, 1993). Scientists observed the actions of the microorganisms present in breaking down the oil and thus, getting rid of it, both on and offshore. Experimental evidences also showed that the microbial actions are affected by factors like temperature and pH. This led to the establishment of a rapidly growing industry which makes uses of microbial remedies to counter water pollution. Modern researches have also proved that waste products produced by one microorganism during biodegradation can be used as a source of food by the others hence, maintaining an environmental food and energy balance (Atlas, 1995). Had petroleum microbiology and bioremediation not been developed to the extent they have been today, our oceans had soon become layered with oil and grease. Moreover, scientific methods involving culture based growths have also been used to study the patterns and behaviors of degrading bacteria and fungi, and gain a better knowledge and understanding of their communities (Vandecasteele, 2008). This provides direction for the development of newer methods and approaches for bioremediation. Recent advancements in the field have resulted in the discovery of a new strain of bacteria called ‘NY3’ which effectively breaks down polycyclic aromatic organic compounds found in large proportions in oils (Oregan State University, 2010). Use of inexpensive techniques of ‘genetic engineering’ have now resulted in economical production of this NY3 and hence, is a very progressive step towards benefitting both the water bodies and the environment. Other situations that require bioremediation is the treatment of infected soil (Van Hamme, 2003). When huge volumes of petroleum waste are dumped in landfills and open spaces, the heavier organic compounds containing hydrocarbons attach firmly to the soil while the lighter ones comprising of short carbon chains are usually volatile and toxic and tend to evaporate rapidly, contaminating and polluting the surrounding air. The use of microbiology to get rid of such hazardous waste is thus, significant. The rates at which the microbes break down the waste products depend on the nature of the compounds as well as the physical conditions present. The most easily biodegradable hydrocarbons are the aliphatic or straight chain alkanes, which are followed then followed by branched alkanes and alkenes. On the other hand, aromatic compounds are very difficult to break down. The important thing about this process is that technically, they do not require any human involvement. However, the natural processes are usually limited by the inadequate supply of nutrients, oxygen, or both. Hence, the implementation of this process in the treatment of soil requires strict supervision by scientists. Scientists have researched on the types of microorganisms that carry out biodegradation at a faster rate and introduce them in soils, along with a rich supply of nutrients. This has helped in reclamation of large areas of land over the years. Processes involving bacteria are also being exploited and given exposure at the commercial level to remove sulfur containing compounds from waste containing petrochemical compounds. Studies have shown that such measures can increase the typical natural rate of biodegradation from 0.5 – 1 percent per month to 0.1 – 0.3 percent per day (Owen, 1992) (Van Hamme, 2003). With the provision of optimum conditions and more efficient microbes, the process of bioremediation can surely be accelerated. An important aspect of bioremediation involves microorganisms that live in plant roots (Van Hamme, 2003). Plantation and growth of such plants in the land contaminated by petroleum waste, leads to an even further efficient treatment. This is because the plant roots provide a suitable habitat for microbes which has rich supplies of both carbonic and nitrogenous nutrients as well as oxygen. Moreover, the harmful volatile compounds are absorbed by the plants and released to the atmosphere as non toxic vapor through transpiration. However, this practice is limited to only small volumes of oily substrate. With the advancement in microbiology, other efforts at removing the toxic vapors have been made. One of them includes the use of capable filters which allow microbes to come in contact with the vapors and hence, break down them down through enzyme action. Sadly, the use of this process has proven very difficult and ineffective. Microbiology has been long been used with petroleum products in order to protect the, already fragile, environment. These methods have been adopted to serve in order to preserve the earth’s environment. Eventually, it brings about numerous advantages upon the environment. For instance, bioremediation, a branch of petroleum microbiology, is of great use to prevent the disastrous effects of oil spills on the environment. It is more of a ‘natural process’, therefore it doesn’t produce any harmful by-products. The microbes used in this process are advantageous to the environment and once they eliminate all the damage done in, for example, an oil spill, they simply die out and become a part of the natural habitat (Das, 2010). In this process, no harmful chemical is brought into use to either enhance the functionality of those microbes; hence there are no possible side effects as well. Probably the biggest advantage, for which industrialists are ready to adopt these methods, is its dramatic cost effectiveness. It lowers the price of degradation by almost 30% to 60% as compared to traditional methods of degradation. Moreover, if any further oil spills may occur in an area which has already been treated with microbes, then no further actions need to be done in that area as those bacteria, which decontaminated the previous oil spill, continue to serve for their function. However, not every de-contamination process brings about only advantages. It has a few, yet considerable, drawbacks. The first and most troublesome drawback is the time consumption. It is a long lasting process that may even acquire a time period spanning years. During this time period, the petroleum products may cause extensive damage to the environment. Secondly, this is a process which is difficult to control. This is because in order to ensure the maximum functionality of the microbes, an ideal environment must be maintained around the region where they are functioning, which definitely gives a boost to the cost of this methodology. Secondly, the microorganisms prefer to feed upon the nutrients that are readily available. So sometimes if the contaminants that are to be decomposed are present in an area that is partly or completely inaccessible, the microbes won’t make any effort on acting on them. Thirdly, in some cases, the injection of bacteria into the habitat may prove harmful for the natural vegetation and may cause infection, not only in the surrounding plants, but in animals as well (Das, 2010). An important, and possibly the largest application of petroleum microbiology is the microbial enhanced oil recovery (MEOR) mentioned above (Belyaey, 2004). According to most microbiologists, the processes are somewhat similar to the bioremediation ones (Van Hamme, 2003). It involves the pumping of small, starved bacteria into an oilfield which are resuscitated when provided with nutrients, contained in the crude oil. The bacteria then grows in size and plug up majority of the pores of the rocks found above the oil. Scientists refer to the bacteria involved as ‘stimulating agents’ who facilitate extraction because when water is pumped down, it is forced to seep into the smaller, lesser porous rocks and thus, helps in pumping the oil to the surface. This concept was first introduced by Beckam in 1926 (Van Hamme, 2003). Alternatively, there are times when microbes are already present within the oil reservoir. In such cases, nutrients required for optimum growth are injected in the field to promote growth and action of the bacteria. The application of this technology needs particular conditions regarding the temperature, pH, availability of nutrients and pressure in the oil field. The only microbes that can be used are the bacteria. This is because no other microorganisms possess either the size or the ability to grow in such conditions as those present in the oil field. For example, high concentrations of sodium chloride present in oil reservoirs limits the use of variable microbes because not all of them can tolerate and withstand these conditions. Moreover, some oil recovering techniques make use of temperatures as high as 70 to 90?C and pressures as high as 20 MPa, and only extreme heat tolerant bacteria can be used. One of the bacteria used commonly in this process is known as Leuconostoc mesenteroides (Van Hamme, 2003). Moreover, sometimes, the flow of oil during extraction is supported by the use of surfactants. These are chemicals which reduce the surface tension of the liquids present, that is oil and water, and make the movement of the heavier or viscous oil fractions easier. At other times, bacteria that produce polymers like xanthan gum are injected into the oil reservoir. The action of the produced xantham gum on water causes it to form a gel – like consistency which then helps in pushing the oil upwards, that is, closer to the surface. In recent years, the popularity of MOER has increased due to a number of reasons which majorly include the process being cheap and economical. Growth and injection of microbes is an inexpensive procedure, and is both easy and efficient to use with little chances of complications occurring. Energy requirements are also low and the implementation of MOER requires only little alterations or modifications to the extraction oil site. It is also an environment friendly procedure as the products of microbial activity are degradable and decompose with time. Most importantly, it contributes to a large increase in oil production. Case studies have shown improvement in oil recovery in 15 to 23 percent oil fields in areas of Japan and China, when methods of nutrient and bacterial injections were used. Studies from United States have proved that the application of MOER has the tendency to increase rate of production from 0.2 to 0.4 tons of oil per day (Van Hamme, 2003). However, the frequent use of MOER leads to the production of sulfate reducing bacteria (SRBs) and compounds like hydrogen sulphide within the oil reservoir. Such bacteria (e.g. Desulfovibrio hydrocarbonoclasticus) use sulfate compounds during metabolism which is a major drawback as it results in acidic compounds being formed within the crude oil. These acidic compounds affect the rocks enclosing the oil field and cause blockage of spaces through which the oil has to flow, making extraction difficult. Their action further leads to the dissolving and corrosion of pipelines during transmission and transport of the petroleum, finally resulting in leaking and bursting of pipelines. To prevent this, regular cleaning and neutralizing of the inner surfaces of pipelines with basic solutions is required which is a laborious and costly procedure (Encyclopedia, 2005). This is why performance of the process of MOER has remained difficult to judge and thus, remains uncertain. The variation in the conditions from field to field and reservoir to reservoir also makes the use of MOER a serious challenge. But the scientists have not lost hope and continue to work hard to find more efficient methods and facilitate the developing of oil recovery. From what we have discussed above, the presence of sulphur in the extracted petroleum is a major problem. Along with that, burning of fuel containing traces of sulphur leads to the formation of sulphur dioxide in the environment, which is an air pollutant. Therefore, it is essential that the extracted petroleum is refined before sold in markets for local use. The most common method used previously in oil refineries was hydrodesulfurization (HDS). However, the expenses and the compromise of quality associated with its practice have led to the use of microbiology become more popular. The recent advances of the century have helped introduce biocatalytic desulfurization (BDS), designed to achieve the same purpose as HDS (Vandecasteele, 2008) (Van Hamme, 2003). The idea was first brought under work when a scientist named Maliyantz observed some bacterial activities that led to the removal of certain amounts of sulphur from crude oil. It involves the use of bacteria that possess specific enzymes and have the capability to remove organosulfur from the compounds of the petroleum through reduction. The BDS process is favourable as it requires mild working conditions and hence saving both energy and costs. Moreover, it requires less hydrogen as the reducing agent and does not result in the generation of any adverse by products. Continuous use of BDS in the future has been predicted to result in a noteworthy reduction in greenhouse gases production and thus is said to be environment friendly (Van Hamme, 2003). A study showed that when Arabian crude oil was mixed with nutrients and a culture of sulfate reducing bacteria, its sulfur content was observed to reduce by 12.5 percent in a time of four days (Van Hamme, 2003). New varieties of microbes have been developed over the years that have the ability to take up sulfur with the purpose of aiding the refining processes. Examples of desulfurizing bacteria include Rhodococcus sp. Strain IGTS8 (Van Hamme, 2003). However, it must be noted that microbiological methods have certain limitations, of which one is the inability of microbes to function efficiently when heavier compounds of larger molecular mass are used. Also, the action of microbes in these procedures lead to the additional breaking of C – C bond which results in the formation of smaller hydrocarbons, which is sometimes not required and thus, becomes an inconvenience. Along with sulfur, crude oil also contains small percentages of nitrogenous compounds. One of such compound is carbazole which acts as an enzyme inhibitor during HDS and also causes poisoning of catalysts during cracking (Van Hamme, 2003). Burning of fuel containing nitrogenous compounds lead to air pollution and acid rain. Traditional methods of denitrogenation involve treating fuel with hydrogen under high temperatures and pressures are extremely expensive. Therefore, use of biotechnology has been made and microbe species that can break down and make use of nitrogenous compounds have been distinguished and are currently used in the industry. Examples include Mycobacterium and Bacillus. However, denitrogenization through biotechnology also faces the dilemma as that discussed above for BDS. Microorganisms and in general, all living things have enzymes. The specificity of enzymes in terms of structure and function along with their ability to act as a catalyst in countless reactions has helped microbiology play an important part in petroleum processing (Van Hamme, 2003). Different types of enzymes found in a variety of microbes are used in industries for the synthesis of a large range of useful products from petroleum. For example, a common enzyme known as naphthalene dioxygenase (NDO) is used to produce a number of different organic alcohols which are needed for many important synthetic reactions and catalysis of a number of oxidations. Other examples include the conversion of alkanes (e.g. octane) into alcohols (e.g. octanol) and aldehydes (e.g. octanal) through the action of alkane hydroxylase found in microorganisms containing the P. olevorans gene. An E. coli strain containing the same gene is also used to synthesize octanoic acid from octane, the chemical name for petrol. Production of chemical compounds is cheap and proficient and is thus, becoming largely popular with the passage of time. Studies show that the manufacturing costs of these products mostly range from 3 to 10 US Dollars per kilogram and are extremely profitable (Van Hamme, 2003). With the rapid pace at which genetic and protein engineering fields are developing in this century, the advancement of enzyme technology in the petroleum industry will continue to take place effectively. Another potential use of petroleum microbiology is the large – scale manufacturing of food. Microorganisms make use of some of the petroleum fractions, especially naptha, to synthesize ‘single - cell protein’, which is a source of nutrition for both animals and humans (Frazzetto, 2003). However, it still remains an area lacking development and marketing. Other valuable materials produced through petroleum microbiology include biological molecules mainly carbohydrates, enzymes, amino acids and nucleotides. Antibiotics and organic acids are also produced as a result of breakdown of petroleum hydrocarbon. These products form the basis of industries like pharmaceuticals, dyes and perfumes (Encyclopedia, 2005). Microbiology is also used in industries to make biodegradable plastics and textile that are environment friendly and contribute to reduction in land pollution (Frazzetto, 2003). In the future, crude oil will continue to remain the most important commercial energy source. However, a time will come when its production will reach its peak and eventually, start to decline. Therefore, in order to fulfill future fuel demands, heavy oil, tar sand and bitumen sources must be exploited. The total world oil reserves comprise of, dominantly, heavy oil reserves and conventional oil reserves have decreased significantly with the passage of time. This is so because heavy oil is extremely dense and thick, therefore it is difficult to pass it through any porous medium. Hence, it is less excavated. If excavators focus on producing heavy oil reservoirs, then it will bring a lot of economic benefits. Biotechnological processes, along with other recovery processes, can bring a revolutionary change for the development of methods to recover and upgrade heavy oils. Several institutes, such as the department of Biotechnology at SINTEF, have gained a lot of experience, throughout the years, in the fields of crude oil and hydrocarbon microbiology and are aspiring to work harder to reach new boundaries of advancement and success. Others like Statoil and the department of Marine Environmental Technology at SINTEF Materials and Chemistry are completely determined to utilize bio-catalytic processes in order to improvise the methods of recovery and up-gradation of heavy oils. Statoil has also collaborated with the Norwegian University of Science and Technology (NTNU) in a Research Council Project, with the objective of construction and use of microbial study based libraries to characterize oil reserves. Petroleum microbiology, and its many procedures are simply aimed to reduce, as much as possible, the polluting by products of petroleum products, and try maintain the already depleting reservoirs of conventional oil. However, with the research mentioned above, it is evident that the adoption of this procedure requires a long term transition from traditional processes and a constant inflow of capital in order to maintain a working environment for these microbes. Therefore, a few rough steps are needed to be taken, in order to build a secure and fuel efficient future for our future generations. WORKS CITED: "Petroleum Microbiology." World of Earth Science. Ed. K. Lee Lerner and Brenda Wilmoth Lerner. Vol. 2. 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