One of the major environmental problems today is hydrocarbon contamination resulting from the activities related to the petrochemical industry. Accidental releases of petroleum products are of particular concern in the environment. Hydrocarbon components have been known to belong to the family of carcinogens and neurotoxic organic pollutants. Currently accepted disposal methods of incineration or burial insecure landfills can become prohibitively expensive when amounts of contaminants are large. Mechanical and chemical methods generally used to remove hydrocarbons from contaminated sites have limited effectiveness and can be expensive. Bioremediation is the promising technology for the treatment of these contaminated sites since it is cost-effective and will lead to complete mineralization. Bioremediation functions basically on biodegradation, which may refer to complete mineralization of organic contaminants into carbon dioxide, water, inorganic compounds, and cell protein or transformation of complex organic contaminants to other simpler organic compounds by biological agents like microorganisms. Many indigenous microorganisms in water and soil are capable of degrading hydrocarbon contaminants. This paper presents an updated overview of petroleum hydrocarbon degradation by microorganisms under different ecosystems.

Reactive species produced in the cell during normal cellular metabolism can chemically react with cellular biomolecules such as nucleic acids, proteins, and lipids, thereby causing their oxidative modifications leading to alterations in their compositions and potential damage to their cellular activities. Fortunately, cells have evolved several antioxidant defense mechanisms (as metabolites, vitamins, and enzymes) to neutralize or mitigate the harmful effect of reactive species and/or their byproducts. Any perturbation in the balance in the level of antioxidants and the reactive species results in a physiological condition called “oxidative stress.” A catalase is one of the crucial antioxidant enzymes that mitigates oxidative stress to a considerable extent by destroying cellular hydrogen peroxide to produce water and oxygen. Deficiency or malfunction of catalase is postulated to be related to the pathogenesis of many age-associated degenerative diseases like diabetes mellitus, hypertension, anemia, vitiligo, Alzheimer's disease, Parkinson's disease, bipolar disorder, cancer, and schizophrenia. Therefore, efforts are being undertaken in many laboratories to explore its use as a potential drug for the treatment of such diseases. This paper describes the direct and indirect involvement of deficiency and/or modification of catalase in the pathogenesis of some important diseases such as diabetes mellitus, Alzheimer's disease, Parkinson's disease, vitiligo, and acatalasemia. Details on the efforts exploring the potential treatment of these diseases using a catalase as a protein therapeutic agent have also been described.

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The purpose of the present study was to determine whether oxidation of various proteins during the aging process occurs selectively or randomly, and whether the same proteins are damaged in different species. Protein oxidative damage to the proteins, present in the matrix of mitochondria in the flight muscles of Drosophila melanogaster and manifested as carbonyl modifications, was detected immunochemically with anti-dinitrophenyl-group antibodies. Aconitase was found to be the only protein in the mitochondrial matrix that exhibited an age-associated increase in carbonylation. The accrual of oxidative damage was accompanied by an approx. 50% loss in aconitase activity. An increase in ambient temperature, which elevates the rate of metabolism and shortens the life span of flies, caused an elevation in the amount of aconitase carbonylation and an accelerated loss in its activity. Exposure to 100% ambient oxygen showed that aconitase was highly susceptible to undergo oxidative damage and loss of activity under oxidative stress. Administration of fluoroacetate, a competitive inhibitor of aconitase activity, resulted in a dose-dependent decrease in the life span of the flies. Results of the present study demonstrate that protein oxidative damage during aging is a selective phenomenon, and might constitute a mechanism by which oxidative stress causes age-associated losses in specific biochemical functions.