Bioremediation Mycoremediation: the role of fungi to rescue the Oil spills - Essay Example

?Bioremediation – Mycoremediation: the role of fungi to rescue the Oil spills Oil spill is a form of pollution that is mainly caused due to the release of chemicals, namely the liquid petroleum hydrocarbons, into the environment, particularly in the marine areas. This mainly happens due to the human activity since it mainly occurs in the marine region; hence, it can be termed as marine oils spills. Moreover, it also occurs in the land. “Oil spills happen when people make mistakes or are careless and cause an oil tanker to leak oil into the ocean. Equipments breaking down may also cause oil spills.” (Oil Spills, 2002). The factors lying behind the marine oil spills are due to the human activity or through any natural disaster like storms and hurricanes. Apart from the above, people may illegally dump the pollutants, such as the crude oil, into the sea. Moreover, terrorists may also cause the oil spills just to destroy the country’s resources. The major victims of the oil spills occurring in the sea would be the aquatic animals and other marine living organisms which include plants under the sea. Thus, cleaning up and recovering from the oil spill are a major tasks and it is mainly based on the factors such as the nature of the oil that is being spilled, the quantity or the amount and the nature of the area being affected. There are different methods for cleaning up the oil spills which ensemble chemical treatment and Bioremediation. Bioremediation is the process of using the microorganisms to break down and remove the pollutants. “Bioremediation usually involves the use of biological agents to detoxify a contaminated environment” (Thangarajan et al., 2011). Therefore, the noxious wastes of the oil spills can be effectively treated with the Bioremediation technology. This paper will mainly feature the Mycoremediation, the implementation of the microorganism, namely the fungi to break down and remove the toxin. “Mycoremediation (“mykes”, fungus and “remedium,” a cure) is a technique that utilizes the vegetative portion of a fungus to remove contaminants from a substrate- usually soil” (Christensen, 2008). Microorganisms such as bacteria, fungi and algae take part in the bioremediation process, among them the biodegradation caused by fungi is known as Mycoremediation as stated above. Generally, the oil spills are rich in hydrocarbons and they are considered to be prime polluting factor. Thus, some strains of fungus act effectively on these hydrocarbons and they degrade them effectively. The fungal mycelium excretes digestive enzymes and these enzymes break down the organic matter when it is absorbed into the fungal cells. The basic concept is that the molecules which are found in the hydrocarbons are similar to that of the carbohydrates which is plant based material and, hence, most of the fungi procure the ability to break down these hydrocarbons present in the oil spills. “Mycoremediation plays a vital role in breaking down the numerous toxic substances like petroleum hydrocarbons, polychlorinated biphenyl, heavy metals (absorption), phenolic derivatives, persistent pesticides, etc.” (Varsha, Deepthi and Chenna, 2011). Hence, as stated above, some strains of fungi utilize some of the hazardous chemical compounds as their nutrient source and they convert them into simpler nontoxic fragment forms. “Fungi are non-photosynthesizing, heterotrophic organism that derives energy from a saprophytic or parasitic existence”(Myco-Remediation, n. d.). Basically, the Mycoremediation process can be divided into three general categories, namely: using the target compound as a carbon source and attacking them, the target compound is being destroyed enzymatically and the hydro carbons in the oil spills are being taken up and concentrated within the organisms instead of being metabolized (Bioaccumaulation). Accordingly, most of the fungi species participate in all the above mentioned biodegradable processes and are more proficient in metabolizing the target compound and the bioaccumulation process. Generally, the two species, namely the Pleurotus ostreatus and Trametes versicolor, have received considerable attention as they are much more effective in mineralizing the oil spills which are rich in hydrocarbons and Polychlorinated Biphyenyls. Consequently, the fungal strain Pleurotus ostreatus produces several Laccase isozymes which are encoded by the families of the laccase genes. “Laccase (p-diphenol-dioxygen oxidoreductase) is a member of the blue copper oxidase family” (Bennet, Wunch, and Faison, 2002). These laccase enzymes oxidize the substrate of the target compound through the one-electron transfer step. Many phenols and chlorophenols are transformed into radicals through the action of these enzymes and they undergo spontaneous polymerization (Gojgic-Cvijovic et al., 2012). Thus, these laccase-mediator combinations also reveal effective activity against the toxic substances such as acenaphthene, acenapthylene, and anthracene, etc. Also a purified form of the laccase isolated form the Trametes versicolor has the ability to oxidize a variety of polycarbonated hydrocarbons such as anthracene, fluroanthene and chrysene, etc. The major attribute that distinguishes the filamentous fungi from the other biodegraders includes their mycelial growth which provides a competitive advantage to the fungi over the other micro organisms. Since the fungi possess the mycelia growth they are able to rapidly ramify through the substrates. “Mycelial networks functions as a filter, allowing water to flow through its membrane, while retaining and dismantling contaminants” (Eyesofgaia, n. d.). Hence, they cause the complete destruction of the target compounds through the secretion of the extra cellular degradative enzymes. Through the hyphal penetration the fungi are able to establish contact with the target compounds ultimately leading to the chemical break down affected by the secreted enzymes. Both the enzymatic and the mechanical contacts with the environment are much assisted by the high surface to cell ratio where in they are able to degrade the oil spills which are rich in hydro carbons. Moreover, the degradative enzymes which are secreted allow the fungi to tolerate and withstand high concentration of the toxic substances in the environment. Thus, the fungi are able to solubilize even complex polymeric substrate and decompose them. “Enzymes form the fungal mycelia which are able to cleave certain atoms like chloride and then break the bond between hydrogen and carbon. (Johnston and Mosco, 2010). Above all, they are able to act on chemically diverse substrates since they are able to secrete the enzymes independent of the target compounds respectively. Another phenomenon of the Mycoremdiation process would be the biosorption by fungi. The pollutants in the form of the petro hydro carbons are concentrated and bound to the cellular structure of the fungi. Basically, it is physiochemical process and it is considered to work more effectively than the bioaccumulation process since the accumulated metal can also be desorbed using the physical methods even without damaging the biosorbent’s structure. Furthermore, most of the strains of fungus can be considered as the most efficient adsorbent since the cell walls and other components associated with play a vital role in the process of adsorption. Thus, many fungal species such as Aspergillus carbonaruius, Aspergillus niger, Rhizopus sp, Saccharomyces cerevisiae have bees stated to have an effective part in the biosorption of the heavy metals which are predominately existing in the oil spills respectively (Moneke and Nwangwu, 2011). Above all, Mycorrhiza, which is a symbiont, encourages the degradation of the organic compounds such as the phenols and other petrochemical contaminants in the soil. Morchella conica and Tylospcno fibrilnsa are the well known Mycorrhizons which have the ability to degrade the organic pollutants naturally. The organic pollutants are rich in the carbon compounds and, hence, these fungal strains can efficiently act on the carbon compounds and oxidizes the pollutants into simpler nontoxic compounds. Therefore, some of the fungal strains such as the Phanerochaete chrysosporium are able to act on a wide variety of pollutants such as the lignin and other petrochemicals mainly because of their uquitious nature and potentiality to oxidize them. “The non specific nature of the system gives the potential for oxidation of a wide variety of chemicals and even mixtures of chemicals” (Aust, 1990). Generally, the crude oil which is the main pollutant through the oil spills significantly consists of huge amount of the Polycyclic Aromatic Hydrocarbons. Since these chemical compounds consist of fused aromatic rings, the white rot fungus, namely Pleurotus pulmonarius, is said to act on the chemical structure of the polycyclic aromatic compounds thereby degrading them ultimately. “White rot fungus would be expected to have greater access to poor bio-available substrates, since they secrete extra cellular enzymes involved in the oxidation of complex aromatic compounds” (Salami and Elum, 2010). Moreover, the main mechanism of the rapid and complete degradation of the hydrocarbons present in the oil spills are mainly brought about by the aerobic mechanisms. Under this phenomenon, the enzymes such as the oxidases and the peroxidases present in the microorganism activate the intracellular attack of the pollutants which is an oxidative process. After the initial intracellular attack, the peripheral degradation process converts the organic pollutants into the intermediates and smaller fragments through the phenomenon of metabolism. Consequently, the concept of mycoremediation technology plays a vital role in degrading the hydrocarbon present in the oil spills. Apart from fungus, the other microorganisms such as bacteria, algae, and yeast also play a pivotal role in biodegradation phenomenon. This part of the paper will focus on the other microbial biodegradation process. “Biodegradation of petroleum hydrocarbons is a complex process that depends on the nature and on the amount of the hydrocarbons present” (Das and Chandran, 2011). Thus, based on the nature and amount of the hydrocarbons present in the environment, a wide variety of microbes can be used for the biological degradation. Apart from fungus, bacteria can be considered as one of the most active agents in the degradation of the petroleum carbon compounds. They act as the primary degrades of the oil spill in the environment. The aerobic bacteria such as the Pseudomonas, Escherichia, Rhodococcus and Bacillus species play a vital role in degradation of the oil spills. They are aerobic bacteria and utilize oxygen for their degradation process. Thus, the main principle of aerobic degradation of hydrocarbons includes the oxidative process which includes the activation and incorporation of oxygen which is the key enzymatic reaction catalyzed by oxidases. Some of the anaerobic bacteria such as Methanospirillium and methanosaeta function even in the absence of oxygen and take part in degradation process. What is more, the applications of the genetically engineered microorganisms have received a great deal of attention in treating the hazardous wastes especially the oil spills. Moreover, the genetically modified bacteria with their changes in the structure of the genes and DNA have shown to have an effective and higher grade of degrading capacity when compared to the other microbial degradation (Romero et al., 2011). Furthermore, the combination of the microbiological and the ecological knowledge along with the biochemical mechanism can bring out effective and innovative methodologies in the field of microbial biodegradation. Other fascinating concept in the field of bioremediation of oil spills includes the usage of the immobilized cells. Immobilization is the process through the contact between the cell and the hydrocarbon particle which are increased and thereby affecting the biodegradation process. The immobilization of the bacteria cells are said to have an enhanced rate of degradation of the hydrocarbons of the crude oil when compared to the free living cells. Hence, when compared with the mycoremediation, some of the microorganisms such as yeasts are also incorporated in the field of microbial biodegration of oil spills. Some of the yeast species such as the Candida maltosa, Candida tropicalis are involved in the process of bioremediation. The enzymes present in these cells, namely the P 450, contribute in the process of metabolic activity where the toxic hydrocarbons are degraded into the non toxic form (Ogbo and Okhuoya, 2011). These yeast species use the alkanes and aliphatic hydrocarbons as the main source of carbon and energy which is greatly assisted through the cytochrome P450. Through this concept, the enzymes are used in the degradation process of the hydrocarbons respectively. Another concept used in the process of bioremediation is Bio-augmentation. “Bio-augmentation is the addition of the microorganisms to the soil where as the bio-stimulation is the modification, addition, reduction or genetic engineering of the microbial colonies to degrade pollutants” (Manzoor, 2011). Thus, as discussed through the process of genetic engineering, modifications are made in their genetic make up thereby making changes in their genotype. With the changes made in the DNA level, the microbes are able to degrade the pollutants in the oil spills effectively and with much less cost. Another fascinating fact is that some varieties of plants are used in bioremediation and the process is termed as Phytoremediation. “Phytoremediation is considered as an innovative, economical and environmentally compatible solution for remediating contaminated sites” (Fulekar, 2010). This can be mainly implemented in the soil which is highly polluted with the hydrocarbons and have all the possibilities of polluting the ground water; in such cases, the concept of Phytoremediation is being implemented. Basically, the natural plants or the genetically engineered transgenic plants are allowed to accumulate the toxic substances from the environment and they bioaccumulate the substances in the parts which are present above the ground level. These parts are later harvested and destroyed completely. Therefore, with the above techniques of bioremediation the usage of fungi in biodegradation namely the Mycoremediation can be much appreciated since they have comparatively more advantages such as micro-filtration, usage of enzymes in degradation, and biosorption and bioaccumulation, etc. Thus, with the assistance of the above mentioned methodologies, the fungi are able to degrade the oil, aromatic compounds, hydrocarbons other hazardous petroleum products. “The fungus is able to degrade effectively both the aliphatic and aromatics to varying degrees”(Ogbo and Okhuoya, 2008). This part of the paper will discuss the strengths and weaknesses of the Mycoremediation. Like the two sides of a coin, the Mycoremediation technology also has advantages and disadvantages. When compared with the other microbial degradation concepts, the Mycoremediation has more advantages than disadvantages. Thus, the advantages include the following: a) When compared to the other techniques it is considered the safest and cost effective process; b) It restores the natural function and balance in the ecosystem c) The end product of the Mycoremediation is nontoxic (Radical Mycology, n. d). Moreover, the enriched soil after the treatment with the fungus can be used for various useful purposes. The technology is fast and flexible, that is, the results can be readily seen and the size of the affected area can be within a small bucket to acres of land or water. On the other hand, some of the disadvantages include the efficiency level; none of the biological system can assure one hundred percent efficiency (Steffen and Tuomela, 2010). Furthermore, it also has the possibilities of affecting the nearby environment. It can be applied universally and it is restricted to certain levels. Above all, the process is still under its juvenile stage and it needs to be implanted effectively. ADVANTAGES DISADVANTAGES It is cost effective and it can be used in the developed and the developing countries Though it is cost effective, it cannot be applied universally The end product is non toxic and the maintenance is a simpler task Though the concept of Mycoremediation is well known, it is still under process and has its difficulties in implementing When compared to the other chemical process of cleaning up the environment, Mycoremediation is more eco-friendly and also demonstrates fast results. Though it is eco-friendly, there are all possibilities of the surrounding environment getting affected in some areas. Every year huge amount of oil spills are dumped in the environment thereby polluting it on an alarming level. If it is not controlled, it may cause huge losses to the biodiversity and will ultimately create imbalance in the ecosystem. Cleaning up of the oil spills through other chemical methods consumes more of time and energy and, hence, it is always advisable to implement bioremediation and, in particular, Mycoremediation which is cheap, efficient, ecofreindly and with less side effects. Thus, Mycoremediation will produce a pollution free environment in future and will make the earth a better place to live in. References Aust, S. D. (1990). Degradation of Environmental pollutants by Phanerochaete Chrysosporium, Microbial ecology, 20 (1), 197-209. Bennet, J. W., Wunch, K. G., & Faison, B. D. (2002). Manual of Environmental Microbiology. Second Edition, ASM Press Washington. Christensen, S. A. (2008). Mycoremediation – Pollution cure? Environmentalism. Retrieved from http://suite101.com/article/mycoremediation---pollution-cure- a72006 Das, N., & Chandran, P. (2011). Microbial Degradation of Petroleum Hydrocarbons Contaminants: An Overview. Biotechnology Research International. 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M., Deepthi, N., & Chenna, S. (2011). An Emphasis on Xenobiotic Degradation in Environmental Clean Up. Bioremediation and Biodegradation, (11), 1-10. Read More