SSC Biology Microbes in Human Welfare Biology in Human Welfare

Introduction

• The strategies for enhancement in food production aim at

-   increasing the amount of food obtained from animals.

-   increasing the yield of agricultural crops.

• Animal Husbandry
• Animal husbandry deals with the care, breeding & management of domesticated animals that are useful to humans.

• Poultry Farming
• Poultry is a rearing of domesticated fowls (chickens), ducks, geese, turkeys, guinea fowls and pigeons.
• Poultry birds exclusively grown for meat are called broilers, layers are for egg production, and cockerel for young male fowls and rooster are mature male fowls.

• Fisheries
• Pisciculture is the rearing, breeding and catching of fishes.
• Aquaculture is rearing and management of useful aquatic plants and animals like fishes, oysters, mussels and prawns, etc.

• Bee keeping or Apiculture
• Apiculture is rearing and breeding of honeybees for the production of honey.
• The commonest species of honeybee is Apis indica.

• Animal Breeding
• Animal breeding is the production of new breeds of domesticated animals with improved traits.

-   Inbreeding: Mating between the closely related animals of same breed.

-   Out-breeding: Mating between the animals which are not closely related.

-   Out-crossing: Mating between the animals of the same breed which do not have a common ancestor.

-   Cross-breeding: Mating between the superior animals of different breeds of the same species.

• MOET (Multiple Ovulation Embryo Transfer) technique is a programme which improves the chances of successful production of hybrids.

• Plant Breeding
• Plant breeding refers to the modification and improvement of genetic material of plants resulting in the development of crops which are more beneficial to human beings.

Table: Crop varieties bred by hybridization and selection for disease resistance to fungi, bacterial and viral disease.

• Examples of insect pest resistance crops bred by hybridization are

(i)  Pusa Gaurav variety of Brassica is resistant to aphids.

(ii) Pusa Sawani and Pusa A-4 varieties of Okra (Bhindi) are resistant to shoot and fruit borer.

(iii) Pusa SEM 2 and Pusa SEM 3 varieties of flat bean are resistance to aphids and fruit borer.

Single Cell Protein (SCP)

• Single Cell Protein (SCP)
• Single cell protein refers to the dried microbial cells or total protein extracted from pure microbial cell culture (algae, bacteria, yeasts and filamentous fungi) which can be used as food supplement to humans or animals.

• Tissue Culture
• Plant cells and plant organs can be cultured in vitro (e.g., in test tube or any other container) on a suitable medium (e.g., agar medium), is called plant tissue culture.
• A plant part excised from its original location and used for initiating a culture is known as explant. The explants, media, vessels and instruments used in tissue culture must be sterilized to make them free from any microbes.

• Microbes in Human Welfare
• Microbes can be grown on culture nutritive media to form colonies which are used for mass production of certain desirable products and for scientific study of metabolism, genetics and structure of micro-organisms.

Lactobacillus lacti: Milk fermentation

Lactobacillus acidophilus: Cheese production

Streptococcus thermophilus: Yoghurt production

• Antibiotics are chemical substances, which are produced by some microbes and can kill or retard growth of other disease causing microbes.
• Alexander Flemming while working on Staphylococci plates observed that in one of unwashed culture plate, it could not grow because of chemical produced by mould Penicilliun notatum grown on it which produces chemical penicillin.

• Microbes in Production of Biogas
• Produced by methanogens, which are anaerobic bacteria growing on cellulosic material and produce large amount of methane along with \[C{{O}_{2}}\]and \[{{H}_{2}}\] e.g., Methanococcus, Methanobacterium.
• Bt Cotton is genetically modified cotton having Bacillus thuringiensis genes. Bacterium Bacillus thuringiensis (Bt) is used as microbial control agent in order to control butterfly caterpillars.

• Microbe as Biofertilisers
• Rhizobium species in root nodules of leguminous plant.
• Azospirillium and Azotobacter are free living species in soil.
• Cyanobacteria such as Anabaena, Nostoc and Oscillatoria (autotrophic micorbes) m paddy field.

• Biotechnology
• It deals with large scale production and marketing of products and processes using living organisms, cells or enzymes.
• Examples of Biotechnology are GMO [Genetically modified organisms], TVF (in vitro fertilization), Test tube babies, DNA vaccines and gene therapy.
• Genetic engineering can be defined as the generation of new combination of heritable material by the insertion of desired genes or DNA sequences, produced by whatever means outside the cell, into any carrier system so as to allow their incorporation into a host organism in which they do normally occur but in which they are able to perform normal behaviour and propagation.
• Three techniques of genetic engineering are:

(i) rDNA (recombinant DNA technology)

      (ii) Gene cloning/gene amplification

(iii) Gene therapy

• Tools of (recombinant DNA technology) rDNA technology are

(i) Vector - Plasmid, Bacteriophage, Cosmid, BAC, YAC

(ii) Host - with Ori C [origin of replication]

(iii) Restriction endonuclease - with well-defined recognition site

• Vectors are cloning vehicles required to transfer DNA of interest from one organism to another.
• Plasmids are extra-chromosomal, circular, double stranded autonomously replicating sequence in bacterial cell. Bacteriophage is virus which infect bacteria. They have special sticky "cos" site to accept foreign DNA.
• Cosmid can be defined as the hybrid vectors derived from plasmids which contain cos site of phage 1.
• BAC (Bacterial Artificial Chromosome): Episome + Foreign DNA.
• YAC (Yeast Artificial Chromosome): Yeast DNA + Marker gene from competent bacteria.
• Marker sequences are the ones whose phenotype gives observable change, e.g., Tetracycline resistance gene, alcohol fermentation gene.
• Palindromic sequence are the ones which read same in one orientation on both the strands.

For e.g., \[\begin{align}

  & 5'-GAATTC-3' \\

 & 3'-CTTAAG-5' \\

\end{align}\] is palindrome as it reads same on both strand in 5' \[\to \]3' direction. Same is true for 3'\[\to \] V direction.

• Restriction Enzymes
• Enzymes that recognizes a specific sequence of double stranded DNA and cut the DNA at that site are called restriction enzymes. They are often referred as molecular scissors.
• Restriction endonuclease was found by Arber in 1963 in bacteria. First was Eco RI found in colon bacterium?

Escherichia coli. Recognition sequence of Eco RI is 5\[5'-GAATTC-3'\]

• Agrobacterium tumefaciens is cloning vector for plants which is T-DNA (transforming DNA) to transform normal plant cell into tumour and direct them to form mass of cells called galls which start secreting chemical required by bacteria.

• Applications of Biotechnology are 
  • GM crop production
  • 

• Therapeutics
• Gene therapy
• Molecular diagnosis

• GM Crop Production - Genetically Modified Crop

(i)   Purpose of introduction of GM crop was to minimise use of fertilisers and chemicals so that their harmful effect on environment could be reduced.

(iii) Examples GM crops are BT cotton and Pest resistant plants. BT cotton: It is a pest resistant plant which resist attack of Lepidopterans insects. The plant BT toxin gene which cause death of insect larvae by causing cell lysis and swelling of epithelium of midgut.

• Bt toxin is biologically produced by bacterium called Bacillus thuringiensis (BT). This toxin is insecticidal protein crystal produced in bacteria (inactive form in bacteria) during a particular phase of growth.
• Transgenic plants are organisms containing a foreign gene from a different species received by genetic engineering.
• Examples of Transgenic plants are

Therapeutics

• Insulin production
• Insulin is a hormone used for diabetic’s patient.
• Insulin was extracted from pancreas of cattle, pigs in limited quantity.
• PCR is a gene amplification technique that has found wide spread use in medicine & molecular biology.
• ELISA is a laboratory test, which can quickly determine antigen or antibody levels in blood or other fluids.
• A single stranded DNA/RNA attached with radioactive molecule is called molecular probe. Molecular probe are used for detection of gene by complementary hybridising in cloned cell, followed by autoradiography.

• Biopiracy
• Biopiracy is use of bioresource by multinational companies and other organization without proper authorization from countries and people concerned without compensatory payment.