Int.J.Curr.Res.Aca.Rev.2020; 8(8): 38-47 International Journal of Current Research and Academic Review ISSN: 2347-3215 (Online) Volume 8 Number 8 (August-2020) Journal homepage: http://www.ijcrar.com doi: https://doi.org/10.20546/ijcrar.2020.808.006 Review on Biodegradation of Organic Compounds and Plastics Chala Dandessa1* and Abiru Neme2 1Jimma Teachers College, P.O.Box 95, Jimma, Ethiopia 2Jimma University, P.O.Box 378, Jimma, Ethiopia *Corresponding author Abstract Article Info Biodegradation is defined as the biologically catalyzed reduction in complexity of chemical Accepted: 08 July 2020 compounds. Indeed, biodegradation is the process by which organic substances are broken down Available Online: 20 August 2020 into smaller compounds by living microbial organisms. The main aim of this review is to show how much microbial communities are important in waste removal biotechnologies. In this review recently published articles about biodegrading microbes were accessed and reviewed following Keywords necessary acknowledgement. When biodegradation is complete, the process is called Organic compound, Chemical, "mineralization". However, in most cases the term biodegradation is generally used to describe Degradation, Aerobic, Anaerobic, almost any biologically mediated change in a substrate. So, understanding the process of Plastic. biodegradation requires an understanding of the microorganisms that make the process work. The microbial organisms transform the substance through metabolic or enzymatic processes. It is based on two processes: growth and cometabolism. In growth, an organic pollutant is used as sole source of carbon and energy. This process results in a complete degradation (mineralization) of organic pollutants. Cometabolism is defined as the metabolism of an organic compound in the presence of a growth substrate that is used as the primary carbon and energy source. Several microorganisms, including fungi, bacteria and yeasts are involved in biodegradation process. Algae and protozoa reports are scanty regarding their involvement in biodegradation. Biodegradation processes vary greatly, but frequently the final product of the degradation is carbon dioxide. Organic material can be degraded aerobically, with oxygen, or anaerobically, without oxygen. Generally microorganisms with biodegrading ability are a promising phenomenon in waste removal technologies without harming life and wasting resources. Introduction aromatics in marine sediments which occurred prior to detectable biodegradation of n-alkane profile of the crude Microbial degradation is the major and ultimate natural oil and the microorganisms, namely, Arthrobacter, mechanism by which one can clean up the petroleum Burkholderia, Mycobacterium, Pseudomonas, hydrocarbon pollutants from the environment. The Sphingomonas, and Rhodococcus were found to be recognition of biodegraded petroleum-derived aromatic involved for alkylaromatic degradation. Microbial hydrocarbons in marine sediments was reported by Jones degradation of petroleum hydrocarbons in a polluted et al. They studied the extensive biodegradation of alkyl tropical stream in Lagos, Nigeria was reported by 38 Int.J.Curr.Res.Aca.Rev.2020; 8(8): 38-47 Adebusoye et al. Nine bacterial strains, namely, solubility and the size of the polymer molecules, Pseudomonas fluorescens, P. aeruginosa, Bacillus microorganisms are unable to transport the polymeric subtilis, Bacillus sp., Alcaligenes sp., Acinetobacter material directly into the cells where most biochemical lwoffi, Flavobacterium sp., Micrococcus roseus, and processes take place; rather, they must first excrete Corynebacterium sp. were isolated from the polluted extracellular enzymes which depolymerize the polymers stream which could degrade crude oil (Das and outside the cells. Biodegradation is defined as the Chandran, 2011). biologically catalyzed reduction in complexity of chemical compounds(Alexander, 1994).Indeed, Plastics are polymers derived from petrochemicals which biodegradation is the process by which organic are further synthetically made from monomers by some substances are broken down into smaller compounds by chemical processes to produce these long chain living microbial organisms (Marinescu and Dumitru, polymers. Plastics are light weight, low cost, highly 2009). When biodegradation is complete, the process is durable and are of high strength. In our daily life the called "mineralization". However, in most cases the term plastics are available in various forms such as nylon, biodegradation is generally used to describe almost any polycarbonate, polyethylene-terephthalate, biologically mediated change in a substrate (Bennet and polyvinylidene chloride, Urea formaldehyde, Wunch, 2002). polyamides, polyethylene, polypropylene, polystyrene, polytetraflouro ethylene, polyurethane and polyvinyl So, understanding the process of biodegradation requires chloride et al., 2009). Widespread studies on the an understanding of the microorganisms that make the biodegradation of plastics have been carried out in order process work. The microbial organisms transform the to overcome the environmental problems associated with substance through metabolic or enzymatic processes. It is synthetic plastic waste. Recent work has included studies based on two processes: growth and cometabolism.In of the distribution of synthetic polymer-degrading growth, an organic pollutant is used as sole source of microorganisms in the environment, the isolation of new carbon and energy. This process results in a complete microorganisms for biodegradation, the discovery of new degradation (mineralization) of organic pollutants. degradation enzymes, and the cloning of genes for Cometabolism is defined as the metabolism of an organic synthetic polymer-degrading enzymes. Strains compound in the presence of a growth substrate that is Rhodococcus rhodochrous ATCC 2967214 and R. used as the primary carbon and energy source (Fritsche, rhodochrous NCIMP 13259 are capable of growing on 2008). Several microorganisms, including fungi, bacteria styrene as a sole carbon and energy source while R. and yeasts are involved in biodegradation process. Algae rhodochrous stains CTM use 2-methylaniline as sole and protozoa reports are scanty regarding their carbon and energy source. 15 Steroids are also degraded involvement in biodegradation (Nilanjana Das, 2011). by some strains of R. Rhodochrous. The Biodegradation processes vary greatly, but frequently the microorganism‘s role is very important for plastic final product of the degradation is carbon dioxide degradation. The different types of microbes degrade (Pramila et al., 2012). Organic material can be degraded different groups of plastics. The microbial aerobically, with oxygen, or anaerobically, without biodegradation has been at accepted and process still oxygen (Fritsche, 2008; Mrozik et al., 2003). underway for its enhanced efficiency (Shimao, 2001). Biodegradation is the chemical dissolution of materials What is biodegradation? by bacteria or by other biological means. Recently biodegradable plastics are of great interest (Gnanavel et Biodegradation is the general term used to describe the al., 2015). Biodegradation takes place by the action of biological conversion of organic contaminants to enzymes, chemical degradation with living organisms. products that are generally lower in free energy. This This takes place in two steps. The first step is the term is often used loosely and interpreted in various fragmentation of the polymers into lower molecular mass ways (Han and Gu, 2010). species by means of abiotic reactions, like oxidation, photodegradation or hydrolysis, or biotic reactions, like The term biodegradable plastics normally refer to an degradations by microorganisms. This step is followed attack by microorganisms on by the bioassimilation of polymer fragments by the nonwater-soluble polymer-based materials (plastics). microorganisms and their mineralisation. This implies that the biodegradation of plastics is usually Biodegradability depends not only on the origin of the a heterogeneous process. Because of a lack of water- polymer, also on its chemical structure and the 39 Int.J.Curr.Res.Aca.Rev.2020; 8(8): 38-47 environmental degrading conditions. The factors, on environments, there has been time for numerous diverse which the mechanical nature of biodegradable materials microorganisms to evolve the capability of utilizing depends on, are their chemical composition, production, hydrocarbons as sources of carbon and energy for storage and processing characteristics, their ageing and growth. Oil-degrading microorganisms are ubiquitous, the application conditions (Isabelle Vroman, 2009). but may only be a small proportion of the prespill Degradable plastic is the one in which the degradation microbial community (Ronald M. Atlas, 2011) (Fig. 2). results from the action of naturally occurring microorganisms such as bacteria, fungi, and algae. There are hundreds of species of bacteria, archaea, and fungi that can degrade petroleum. Most petroleum Significance of biodegradation hydrocarbons are biodegradable under aerobic conditions; though a few compounds found in crude oils, One of the major environmental problems today is for example, resins, hopanes, polar molecules, and hydrocarbon contamination resulting from the activities asphaltenes, have practically imperceptible related to the petrochemical industry. Accidental releases biodegradation rates. Lighter crudes, such as the oil of petroleum products are of particular