INTRODUCTION
The
microbial genetics as well as the molecular biology specifically and predominantly focus
upon the very nature of
‘genetic information’. Besides, it invariably modulates the precise development
and function of various cells and organisms. In fact, the application of microorganisms has been
enormously useful in mustering a definitely better and exceptionally vivid in-depth understanding of the
actual mechanism of
‘gene function’.
Importantly, it has been adequately observed that practically most of the
‘microbial traits’ are
either strategically controlled or logically influenced due to
heredity. In true sense, the inherited traits
of microorganisms
essentially comprise of the following cardinal aspects :
•
shape and structural features i.e., morphology,
•
biochemical reactions i.e., metabolism,
•
ability to move or behave in different manners, and
•
ability to interact with other microorganisms — thereby causing human ailment.
In a rather broader perspective one may consider that the individual organisms prominently do
transmit these characteristic features directly to their offspring
via genes, that are nothing but the hereditary
materials (DNA) which essentially possess relevant information(s) that precisely determines these typical
characteristic features.
It has been amply proved and duly established that almost all
‘living organisms’ prominently
find it rather advantageous to share the hereditary materials derived from a
‘genetic pool’. However,
under the influence of an effective environmental change, the microorganisms that critically possess
such
‘genes’ which are proved to be advantageous under these new conditions* shall definitely exhibit
a better chance (scope) of reproduction thereby enhancing their actual numbers in the overall population.
Both
eukaryotic and prokaryotic organisms usually exhibit different types of reproductive means,such as :
Eukaryotic Organisms
— invariably make use of ‘sexual reproduction’ having its distinctly
improved survival value
vis-a-vis its sharing capacity with respect to this general ‘gene pool’.
Prokaryotic Organisms
— usually do not have the capacity for sexual reproduction as such.
Thus, they essentially acquire other mechanisms so as to avoid the
‘genetic uniformity’, which could
prove even
‘fatal’ in the microbial species when certain experimental parameters, namely : development
of an antibiotic.
Importantly, in the recent past the
‘microbial geneticists’ do play a vital and an important role in
the ever developing field of
‘applied microbiology’ which gives rise to the production of altogether
‘newer microbial strains’
that predominantly possess remarkably higher efficiency in the syntheses of
medicinally and commercially
useful end products.
Salient Features :
The salient features of the ‘microbial genetics’ are as enumerated under :
(1)
Genetic Techniques are largely employed to test such substances that have the ability to
cause
neoplasm (cancer).
(2)
Genetic Engineering is the most recent outcome of the ‘microbial genetics’ and ‘molecular
biology’
that has enormously contributed to various dynamic scientific studies viz., microbiology, biology,
and
medicine.
(3) Meticulously
‘engineered microorganisms’ are invariably utilized to produce a plethora of
extremely useful
‘life-saving drugs’, for instance : hormones, antibiotics, vaccines, and a host of
other drugs.
(4)
‘New Genes’ may be strategically inserted into the animal and plant species :
Example :
Development of wheat and corn nitrogen-fixation genes so that they may not absolutely
require
nitrogen fertilizers viz., urea.
The earlier investigative studies by Beadle and Tatum, to make use of microorganisms
e.g., bread
mold
Neurospora, provided sufficient vital clues with respect to the ‘genetic control and influence of
the cellular functions’.
Subsequently, bacteria and viruses have actually played an important and
major role
to substantiate and elucidate further the various intricating mechansims of the genetic control.
Advantages :
The various cardinal advantages in employing the ‘microorganisms’ for an
elaborative genetic studies are as detailed below :
(1) Fast rate of growth
e.g., E. coli may duplicate in 20 minutes at 37° C,
(2) Greater ease with which relatively large populations of microbes may be handled in a laboratory
e.g.,
a single sterile petri-dish may hold upto 200–300 colonies,
(3) Relatively much simpler
‘growth media’ for the microbes are needed, and
(4) Much simpler features of the
‘genetic material’ required.
The present subject matter in this particular chapter shall be treated under the following
two
major heads :
(
a) Microbial Genetics, and(b) Microbial Variations.