Recombinant DNA Technology and Genetically Modified Foods

Recombinant DNA Technology

  • Definition: Modifying an organism's phenotype by integrating genetically altered vectors into its genome.
  • Process: Introducing foreign DNA containing a gene of interest into a host organism.
  • Recombinant Gene: The introduced gene.
  • Genetic Engineering: Popularly known as recombinant DNA technology.
  • Key Scientists: Boyer and Cohen (1973).
  • Restriction Enzymes: Discovered by Werner Arbe in 1968; proteins that cut DNA at specific sequences.
  • Process Steps:
    • Desired gene selection.
    • Vector selection for gene integration.
    • Recombinant DNA introduction into the host.
    • Maintenance and propagation in the host.

Tools of Recombinant DNA Technology

  • Enzymes:
    • Restriction enzymes: cut DNA.
    • Polymerases: synthesize DNA.
    • Ligases: bind DNA fragments.
  • Restriction Enzymes:
    • Endonucleases: cut within DNA strands.
    • Exonucleases: remove nucleotides from strand ends.
    • Sequence-Specific: Recognize and cut at palindrome sequences at restriction sites.
    • Sticky Ends: Created by cuts at non-adjacent locations on DNA strands.
    • Blunt Ends: Created by straight cuts across DNA strands.
  • Vectors:
    • Function: Carry and integrate desired genes into host organisms.
    • Common Vectors: Plasmids and bacteriophages (high copy number).
    • Components:
      • Origin of replication: initiates replication.
      • Selectable marker: antibiotic resistance genes (e.g., ampicillin).
      • Cloning sites: restriction enzyme recognition sites for DNA insertion.
    • Plasmid: extra−chromosomalDNAextra-chromosomal DNA capable of independent replication in bacteria.
    • Bacteriophage: Virus that infects bacteria.

Host Organism

  • Role: Receives recombinant DNA.
  • Insertion Methods:
    • Microinjection: Direct injection using a fine needle.
    • Biolistic/Gene Gun: Projectiles coated with DNA shot into cells.
    • Alternate Cooling and Heating: Induces temporary membrane pores.
    • Calcium Ions: Neutralize DNA charge to facilitate uptake.

Process of Recombinant DNA Technology Steps

  • Step 1: Isolation of Genetic Material
    • Isolate desired DNA in pure form.
    • Enzymes Used: lysozymes, cellulase, chitinase, ribonuclease, proteases, etc.
    • Purification: Ethanol precipitation to spool out purified DNA.
  • Step 2: DNA Splicing
    • Restriction enzymes determine gene insertion location.
    • Restriction enzyme digestion: Purified DNA incubated with selected enzyme.
    • Specific DNA sequence recognition and cleavage.
    • Electrophoresis separates digested fragments.
  • Step 3: Amplifying Gene Copies via PCR
    • PCR: Amplifies single DNA copies into millions.
    • Use: Generate sufficient DNA for manipulation, analysis, or vector insertion.
  • Step 4: Ligation of DNA Molecules
    • Joining DNA fragment and vector using DNA ligase.
    • Sticky ends anneal to form new rDNA.
    • DNA ligase creates phosphodiester linkages.
    • Resulting molecule: Recombinant DNA molecule.
    • Recombinant Proteins: Proteins produced via recombinant DNA.
  • Step 5: Insertion of Recombinant DNA Into Host
    • Transformation: Introduction of recombinant DNA into host cells.
    • Multiplication and expression of the protein.
  • Step 6: Selection & Screening of Transformed Cells
    • Identify cells that incorporate recombinant DNA using selectable markers (e.g. antibiotic resistance).
  • Step 7: Validation of Recombinant DNA Integration
    • Verify integration with techniques like nucleic acid hybridization and blue-white screening.

Applications of Recombinant DNA Technology

  • Medicine and Research: gene identification, mapping, and sequencing.
  • Disease Detection: detecting diseases like HIV.
  • Agriculture: developing genetically engineered crops.
  • Gene Therapy: correcting gene defects.
  • Antibody Probes: examining protein synthesis.

Limitations of Recombinant DNA Technology

  • Environmental Contamination: Gene pollution risks.
  • Superweeds: Development through hybridization and gene transfer.
  • Potential Toxicity: Possible toxic metabolites or proteins in rDNA-modified plants.

Genetically Modified Foods (GM Foods/ GMOs)

  • Definition: Plants with altered genetic material using genetic engineering.
  • Process: Introducing genes from other organisms to confer desirable traits.
  • GM Plants: Modified to enhance traits like herbicide tolerance or nutritional quality.
  • International Scenario:
    • Top Producers: USA, Brazil, Argentina, Canada, and India.
    • USA: Largest producer, planting 37.6% of global biotech crops.
  • National Scenario:
    • Bt Cotton: Only approved GM crop in India since 2002.
    • Unapproved GM Crops: Punishable offense (Environment Protection Act, 1989)
  • Genetic Modification Stages:
    1. Gene Identification.
    2. Gene attachment to a carrier (plasmid).
    3. Addition of a promoter.
    4. Gene insertion into a bacterium for copy creation.
    5. Examination of traits.
    6. Breeding with conventional plants.

Examples of Genetically Modified Foods

  • Golden Rice:
    • Modified to produce higher β−caroteneβ-carotene content to combat vitamin A deficiency.
  • Bt Brinjal:
    • Modified with cry1Accry1Ac gene from Bacillus thuringiensis to resist Brinjal Fruit and Shoot Borer (BFSB).
  • FlavrSavr Tomato:
    • Modified to suppress polygalacturonase (PG) gene, increasing firmness and shelf life.
  • Bt Cotton:
    • Expresses endotoxin protein from Bacillus thuringiensis.
    • Confers resistance to bollworms.
  • Genetically modified potato:
    • Carrying gene Cry3A from soil bacteria Bacillus thuringiensis to control potato beetle.

Challenges of GM Crops

  • Environmental Concerns
  • Potential Harm to Human Health
  • Economic Issues
  • Impact on Traditional Farming Practices
  • Increased Chemical Use
  • Market Monopoly
  • Antibiotic Resistance

Regulatory Framework

  • India: GEAC approves/disapproves GM food releases.
  • FSSAI: Regulates processed foods with GM ingredients (Food Safety and Standards Act, 2006).
  • Distinction: FSSAI regulates processed (nonviable) GM foods, while GEAC handles viable plant material.

Bioreactors

  • Definition: Apparatus for growing organisms used in production (pharmaceuticals, antibodies, vaccines) or bioconversion.
  • Function: Sustain and support cell and tissue cultures under optimal conditions (temperature, pH, gas flow, etc.).
  • Components:
    1. Fermentation Vessel: Double-jacketed cylinder made of stainless steel or glass.
    2. Sparger: Provides sterile air to ensure aeration.
    3. Heating and Cooling Device: Double jacket with cold water circulation; thermostatically controlled baths.
    4. Baffles: Prevent vortex formation and improve aeration.
    5. Impellers: Maintain microbial cell suspension and uniform air distribution. Vortex is a circular motion that can form in a fermenter when an agitator rotates in a liquid, causing improper mixing and difficult gas exchange
    6. Valves: Control liquid flow.
    7. Sensors: Monitor temperature, foam level, pH, dissolved oxygen, etc.

Fermentation

  • Definition: One of the oldest methods of preserving foods.
  • Benefits: Aids digestion, enhances flavor, reduces food safety concerns.
  • Upstream Processing: Selection and propagation of microbial cultures.
  • Process Control: Bioreactors maintain optimal conditions.
  • Downstream Processing: Product separation, sterilization, packaging, etc.
  • Types of Fermentation:
    • Homo Fermentation: Single product formed (e.g., glucose to lactic acid).
    • Hetero Fermentation: Multiple products formed (e.g., lactic acid, ethanol, CO2).

Fermentation Systems

  • Submerged Liquid Fermentation:
    • Cultivation: Microorganisms in enriched liquid broth.
    • Industrial Applications: Enzyme synthesis, etc.
    • Substrates: Molasses and broths.
    • Enzymes: Harvested by removing insoluble products and concentrating the broth.
    • Modes:
      • Batch Mode: All prerequisites added at once.
      • Fed-Batch Mode: Substrates added as needed.
      • Continuous Mode: Constant nutrient feed and removal of spent medium.
  • Surface Fermentation:
    • Cultivation: Microorganisms on liquid surface.
    • Uses: rare.
  • Solid State Fermentation:
    • Definition: Fermentation in near-absence of free water.
    • Substrates: Grains, rice, wheat, etc.
    • Benefits: Use of nutrient-rich waste materials.\

Solid State Fermentation Factors

  • Micro-organism: filamentous fungi
  • Substrate: Provide physical support and nutrients to the growing culture.

Food Waste

  • Definition: Edible food that is thrown away, lost, or left uneaten.
  • Global Impact: Approximately 1.3 billion tons wasted annually.
  • India: 68.7 million tons wasted annually, 55 kgs per person.

Economic Los

  • India wastes approximately 92,000 crore/year, equivalent to 1% of India's GDP

Wastes Produced by Various Food Industries

  • Fruit and Vegetable Industry: leaves, peel, pomace, rind, stem, seeds, spoiled fruits and vegetables
  • Meat industry: body hairs, blood, fat, feathers at the slaughterhouse
  • Oil industry: wastewater, organic solid waste (i.e., seeds and husks) and inorganic residues
  • Dairy industry: suspended solids and organic matter, some whey concentrates oils, grease, residues of cleaning products, nitrogen, phosphorus, sodium chloride residue etc.

Food Waste Management - Way Forward

  • Streamlining the Supply Chain: efficient supply-chain practices such as cold storage facilities and better inventory management.
  • Effective Management of Excess Food : Redirect excess food to NGOs.
  • Govt. Policies : Proper policies for food wastage.
  • Sustainable Waste Management:
    1. Prevention
    2. Minimization
    3. Reuse
    4. Recycling
    5. Disposal

AI's Role in Food Waste Management

  • Functions:
    • Demand Forecasting: predict future demand for food products.
    • Quality Control: assess the quality of perishable goods.
    • Shelf-Life Prediction: estimate the remaining shelf-life of perishable items.
    • Supply Chain Optimization: enhance transportation routes, scheduling, and logistics.
    • Smart Inventory Management: optimize the management of inventory.
    • Donation and Redistribution: connect food producers, retailers, and food banks.
    • Consumer Engagement: educate and engage consumers in reducing food waste.

Waste utilization

  • Fat: mango processing ends up in considerable proportion of peel and stones. The estimated fat content in mango kernel is more than 10 per cent.
  • Magaz: It is a seed kernel, confectionary, bakery, ice creams and beverages.
  • Starch: presently more than 1,40,000 tonnes of starch is available from mango seed kernel and 4- 5 tonnes starch per thousand banana plants is available.
  • Tutti-Frutti: extracted papaya and water melon rind after removal of green portion are most suited for the production of tutti-frutti
  • Amchur / pickle: Dropped green mangoes may be used for the preparation of pickles, amchur and raw mango slices.
  • Food grade flavours: Citrus is a good source of flavour. It is a by-product from shaved citrus peel.
  • Chutney: utilize fresh apple pomace, grape pomace, mango and tomato wastes to prepare chutney
  • Edible oil: Apricot kernel, grape seed and citrus seed.
  • Flour and fortified atta: Jack fruit seeds, mango kernel and residues left after extracting juice or the unmarketable surplus of fruits like anola and jamun, and vegetables. This flour is used as health protective flour.
  • Jam and jelly: apple pomace to make jelly.
  • Marmalade: is prepared from citrus peel.
  • Candied peel: prepare candied peel from orange or grape fruit peel.

Wastes preparation for industrial products

  • Oil: Cashew shell contains about 20 per cent oil and resin.
  • Pectin: mango and citrus peel, apple pomace, raw papaya, cashew apple, etc.
  • Essential oil: peel oil in small- scale unit.
  • Natural colour: grape skins, kokum (Garcinia indica), phalsa (Grewia subinaequalis), jamun, safflower, etc.
  • Cups and plates: banana plant leaves are used to prepare disposable cups and plates.
  • Citric acid from lemon peel
  • Varnish and resin from tomato peel
  • Surfactants, wetting agents and detergents from tomato seed meal
  • Citrus seed and mango kernel oils for soaps and detergents
  • Glucosides and bioflavins anti-oxidants from citrus peel
  • Papaya latex for proteolytic enzyme papain
  • Paper pulp from banana stem
  • Fibre from pineapple leaves, mango peel and apple pomace.

Wastes preparation for animals

  • Citrus wet peel: Wet peel contains 70-90% moisture. Wet peel or fresh peel is consumed by the animals directly.
  • Citrus dried peel: dried peel is the most common form of animal feed. Process the dry peel into pellets or powder bran.
  • Skin, core, trimmings, shreds and leaves: feed them directly to the animals or dry for future use in various forms.
  • Wet pineapple bran: pineapple skin and ends are the major source of pineapple bran
  • Dry pineapple bran: dried form of wet bran and transportable.
  • Poultry feed: banana peel, mango seed kernel, dried mango peel and citrus and tomato seeds.
  • Tomato waste: After extracting varnish from peel and oil from seed, marc used as cattle feed.