Saran's Learn Microbiology

BIODETERIORATION Deterioration is defined as a loss of structural capacity with time as a result of the action of the external agents or material leaching. Biodeterioration is the chemical or physical alteration of a product that decreases its usefulness for its intended purpose, caused by micro or macroorganisms or their enzymes. In 1965, Hueck defined Biodeterioration as “Any undesirable change in the properties of a material caused by the vital activities of organisms”. This is the widely accepted definition for Biodeterioration. In 1981, Rose defined Biodeterioration as “The process by which Biological agents are the cause of the lowering of quality or value”. Biological deterioration caused by Insect attack and Fungal growth and the other form of Deterioration is caused by adverse environmental conditions such as extremes of dampness or wide fluctuations in relative humidity associated with large variations in day and night temperatures, light and atmospheric pollutants. Both Biod

BIOLEACHING Bioleaching or Metal Bioleaching or Biomining is a process in Mining and Biohydrometallurgy (natural processes of interactions between microbes and minerals) that extracts valuable metals from a low-grade ore with the help of microorganisms such as Bacteria or Archaea. Bioleaching is an alternative to more traditional physical and chemical methods of mineral processing. The application of Biomining processes predates by centuries the understanding of the role of microorganisms in Metal extraction. However, the modern era of biomining began with the discovery of the bacterium Thiobacillus ferrooxidans . Bioleaching techniques are often more effective than traditional mining applications and can even be used to clean Mine Tailings Sites. METALS EXTRACTED FROM BIOLEACHING Bioleaching is one of several applications within Biohydrometallurgy and several methods are used to recover a)   Antimony b)   Arsenic c)   Cobalt d)   Copper e)   Gold f)   Lead g)   Molybdenu

BIOREMEDIATION Bioremediation is a process that uses naturally occurring or genetically engineered microorganisms such as yeast, fungi, and bacteria to transform harmful substances into less toxic or non-toxic compounds. Bioremediation has been used since the late 1970s to degrade Petroleum product and Hydrocarbons. During Bioremediation, microorganisms break down a variety of organic compounds in nature to obtain nutrients, carbon, and energy for growth and survival. Bioremediation promotes the growth of microorganisms to degrade contaminants by utilizing those contaminants as carbon and energy sources. Forms of Bioremediation There are two basic forms of Bioremediation currently practiced. They are Bioaugmentation (microbiological approach) - Biological augmentation is the “Addition of Archaea or Bacterial cultures” required to speed up the rate of degradation of a contaminant. Organisms that originate from contaminated areas may already be able to break down waste, but perhaps in

XENOBIOTICS The term Xenobiotic comes from the Greek for xeno (foreign) and biotics (of or pertaining to life). Xenobiotic compounds are man­ made chemicals that are present in the environment at higher concentration. These are either not produced naturally or are produced at much lower amount than that by man. Microorganism have the capability of degrading all naturally occurring compounds; this is known as “The principle of Microbial Infallibility” proposed by Alexander in 1965. Recalcitrant The Xenobiotic compounds that resist biodegradation and persist in the environment for long period of time, so they are called as Recalcitrant. The Xenobiotic compounds may be recalcitrant due to one or more of the following reasons ü   Not recognized as substrate by degradative microorganisms and enzymes. ü   Highly stable in nature ü   Insoluble in water ü   Unusual bonds or bond sequences (as in tertiary and quaternary compounds) ü   Unusual substitution (as with chlorine and other

IRON CYCLE Iron (Fe) is one of the most abundant elements in Earth’s crust. The Iron cycle (Fe) is the Biogeochemical cycle of Iron through the Atmosphere, Hydrosphere, Biosphere and Lithosphere. STEPS INVOLVED IN IRON CYCLE On the surface of earth, Iron exists naturally in Two oxidation states, (i) Ferrous [Fe 2+ or Fe(II)] and (iii) Ferric [Fe 3+ or Fe(III)]. A third oxidation state, Fe 0 is abundant in Earth’s core and is also a major product of human activities from the smelting of Iron ores to form Cast iron. Iron cycle has two steps. They are   Ferrous iron oxidation Ferric iron reduction Iron cycle (Oxidation – Yellow; Reduction – Red) 1) Ferrous Iron Oxidation In Ferrous iron oxidation, the Ferric iron (Fe 3+ ) is reduced to the Iron ore (Fe 0 ) and then oxidized to Ferrous iron (Fe 2+ ). This reaction is a Chemical oxidation process. The oxidized Ferrous iron (Fe 2+ ) is again reduced to Iron ore (Fe 0 ). The Ferrous