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Showing posts from April, 2014

MICROBIAL INFECTIONS OF HUMANS(HUMAN MICROBIOLOGY)

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TYPES OF ASSOCIATION:










Ignoring a low rate of mutation as a source of heterogeneity, bacterial division results in clonal 
expansion, with the daughter cells considered to be similar if not identical to the parent cells. 
Collectively, these cells are called a population. However, bacteria rarely exist as a single species 
within any one habitat but, instead, are usually found as collections of different species called 
communities, where each particular species will exist in a particular niche but may well contribute to 

the maintenance of the entire community (e.g. syntrophism). 
Interactions between microbial communities may have a negative (e.g. competition) or positive (cooperation) outcome. The interactions will be between both a single population (i.e. between members of 
the same species) or between members of different populations. Typically, co-operation will occur at 
low population densities, whereas competition will dominate at high population density. The net effect 
will regulate …

MICROBIAL BIOTECHNOLOGY: SCOPE, TECHNIQUES CONTD

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MICROBIAL WHOLE-CELL BIOREPORTERS:

Over a quarter-century ago,luminescent bacteria were introduced as bio-sensors for the rapid assessment of toxic compounds in aquatic environments. The use of these organisms has now become “institutionalized” for
a wide range of toxicological assays. These assays are versatile because the
change in signal (bio luminescence) is linked directly to change in the global
metabolism of the cell independent of the cause.
The advent of genetic manipulation by recombinant DNA technology has
created a broad range of specific microbial bio-sensors. The great majority of
these are genetically engineered bacteria within which a promoter–operator
(the sensing element) responds to the stress condition (toxic organic or

inorganic compound, DNA damage, etc.) and changes the level of expression of a reporter gene that codes for a protein (the signal). The protein may be detected either directly (e.g., green fluorescent protein) or through its catalytic activity (e.g., formati…

MICROBIAL BIOTECHNOLOGY: SCOPE, TECHNIQUES CONTD

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ENVIRONMENTAL APPLICATIONS OF MICROORGANISMS:

3) BIOMINING: HEAVY METAL EXTRACTION USING MICROORGANISMS:

Biomining utilizes naturally occurring prokaryotic communities. Here,microorganisms are used to leach metals, principally copper but also nickel and zinc, from low-grade sulfide- and/or iron-containing ores. The process exploits the energy metabolism of various acidophilic chemolithoautotrophs that utilize inorganic compounds as energy sources and carbon dioxide as the
source of carbon. These organisms use either ferrous iron or sulfide as an
electron donor and oxygen as an electron acceptor with the formation of
ferric iron or sulfuric acid. In the first case, the subsequent reaction of Ferric ions
with insoluble metal sulfides yields soluble metal sulfates; in the second,
metal sulfides are oxidized directly to metal sulfates. The metals are readily recovered from the leachate by electrolytic procedures, and the residual
solution is recycled.
Gold is inert to microbial action. However, bi…

MICROBIAL BIOTECHNOLOGY: SCOPE, TECHNIQUES CONTD

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ENVIRONMENTAL APPLICATIONS OF MICROORGANISMS:

2) BIO REMEDIATION: Bioremediation depends on the activities of living organisms to clean up pollutants dispersed in the environment. Physical or chemical treatments, such
as vaporization, extraction, or adsorption, relocate rather than remove pollutants. In contrast, there are many instances in which biodegradation converts organic pollutants to harmless inorganic products, including carbon dioxide, water, and halide ions. Other advantages are that bioremediation
is generally inexpensive and causes little disturbance to the environment. Naturally occurring consortia, frequently dominated by bacteria, have the capacity to degrade a wide spectrum of environmental pollutants.
Notably, such consortia are responsible for the cleanup of massive oil spills. There is a long list of oil spills with serious environmental impact. Following are three of many examples of this type of widely dispersed pollution. In March 1989, some 41 million liters (>1…