Biotechnology: Class 12 — Chapter 12: Recent Innovations in Biotechnology

• Biofuels: Fuels produced from biological products, living organisms, or organic waste (e.g., landfills, recycled vegetable oil). Also known as agrofuels when derived from specific crops like soybeans, jatropha, pongamia, palm oil, and algae.
• Biodiesel: Produced from animal fats, vegetable oils, and crops (e.g., Pongamia pinnata, mustard, flax, canola) via trans-esterification. Contains higher hydrogen/oxygen and less carbon than fossil diesel, reducing particulate emissions. Can be used in pure form or as a blend (e.g., 5% blend in Europe) without engine modification.
• Bioalcohol: Bioethanol produced via fermentation of sugars released from starch or cellulose in wheat, corn, sugarcane, molasses, sugar beets, potato, and fruit waste.
• Biogas: Produced by anaerobic breakdown of organic substances (dung, manure, wastewater) by bacteria in an anaerobic digester. Consists primarily of methane ($CH_4$) and carbon dioxide ($CO_2$). Serves waste removal, environmental management, and energy production.
• Biomass: Solid biofuels (wood, sawdust, coal, agricultural waste, cow dung cakes) used directly for heating. Combustion emits pollutants like particulate matter and polycyclic aromatic hydrocarbons (PAHs).

Box 1: Ethanol Blending in Petrol

Ethanol is blended with petrol in ranges from 2% to 30% globally. In India, the government permits up to 10% blending, with the Bureau of Indian Standards (BIS) recommending a 5% target. While it reduces fossil fuel consumption and greenhouse gas emissions, high ethanol blends can reduce engine efficiency, cause sputtering, oxidize aluminum in carburetors, and rust steel components.

• Bioplastics: Biodegradable alternatives to petroleum-based plastics made from plant materials (corn starch, bamboo, seaweeds) and natural biopolymers. Polyhydroxybutyrate (PHB) is produced commercially via fermentation with Alcaligenes eutrophus or transgenically in Arabidopsis (targeting chloroplasts) and Populus leaves.
• Biotechnology in Paper Industry: Biopulping uses lignin-degrading fungi to treat wood chips, reducing energy and chemical demands. Biobleaching utilizes enzymes like xylanase to reduce chlorine usage. GM trees with reduced lignin content are also utilized.
• Biotechnology in Oil Recovery: Enhanced Oil Recovery (EOR) uses microbes and their metabolic products to extract residual oil. Genetically engineered Pseudomonas bacterium ("superbugs") are deployed to degrade hydrocarbons and clean up oil spills.

Bioremediation employs microorganisms to reduce toxicities of chemical pollutants (heavy metals like $As$, $Cr$, $Hg$, $Cd$, $Zn$) in soil or water. Selection of strategy depends on three key principles:

1. Possibility of the pollutant to undergo biological transformation to less toxic products.
2. Bioavailability of the contaminant to the microorganisms.
3. Efficiency of the bio-activity at the contaminated site.

• Herbicide Tolerant GM Crops: Developed to withstand non-selective herbicides like glyphosate. Achieved by introducing a modified gene from Agrobacterium encoding a resistant form of the target enzyme (usually in the chloroplast), creating commercial varieties like Roundup Ready canola, soybean, corn, and cotton.
• Disease Resistant GM Crops:
  • Viruses: Resistance achieved by introducing genes for viral coat proteins (acting like a plant vaccine) against yellow crookneck in squash, potato mosaic, and papaya ringspot virus (PRSV).
  • Fungi: Enhanced by incorporating antimicrobial proteins called defensins (e.g., alfalfa defensin in potatoes against Verticillium dahlia), resveratrol genes from white grapevine, Rpi-vnt1.1 gene in potatoes against late blight, and chitinase genes.
  • Bacteria: Resistance engineered by transferring lysozyme genes into potatoes against blackleg and soft rot (Erwinia carotovora).
  • Insects: Engineered using crystal (Cry) proteins or delta-endotoxins from Bacillus thuringiensis (Bt). These proteins bind to specific receptors in the insect gut, destroying cells. Examples include Bt cotton and Bt brinjal.
  • Plant Nematodes: Transgenic strategies in potatoes, bananas, and soybeans achieve up to 70% nematode resistance in field trials.

The CRISPR-Cas9 system uses a guide RNA bound to target DNA and the Cas9 nuclease to edit genes precisely. It bypasses Mendelian inheritance limits to transfer specific traits across generations rapidly. Applied in rice, tomato, and soybean to improve yield, nutritional quality, and stress tolerance. Challenges include off-target effects, low efficiency, and regulatory/safety concerns.

• Stem Cell Technology: Stem cells can proliferate and differentiate to replace dead or damaged cells. When placed in a hydrogel (e.g., Matrigel) with exogenous factors, they self-assemble into 3D structures.
• Organoids: Ultra-small, self-assembled 3D tissue cultures derived from pluripotent stem cells (PSCs) or adult stem cells (ASCs). They mimic organ complexity, spatial cell organization, and cell-matrix interactions.
• Spheroids: Multicellular 3D cell aggregates (e.g., tumor spheres) obtained via mechanical dissociation, dependent on suspension culture or non-adherent surfaces, lacking the ordered self-assembly of organoids.

Computer-assisted 3D Bioprinters construct tissue-engineered scaffolds using bioink (biopolymers embedded with cells and nanoparticles containing growth factors) based on MRI/CT dimensions.

• Carticel: Autologous cartilage cells (chondrocytes) expanded in vitro and implanted to treat cartilage injuries.
• laViv: Autologous fibroblasts injected into the face to remove wrinkles or for cosmetic nose reconstruction.
• Dermagraft: A patch of allogenic fibroblast dermal substitute used to treat diabetic ulcers.

Conversion of bulk materials to nanoscale alters their physicochemical, biological, mechanical, optical, and electronic properties due to an exponential increase in surface-area-to-volume ratio.

• Gold Nanoparticles: Bulk gold is golden; nanoparticles smaller than 30 nm are ruby red, up to 100 nm are pink, and larger particles appear darker.
• Quantum Dots (QDs): Cadmium-selenium ($CdSe$) nanocrystals of different sizes that produce distinct fluorescence colors that do not quench with light, used in diagnostic imaging.

• Nanomedicine & Drug Delivery Systems (DDS): Nanocarriers (20 to 30 nm) target diseased sites, increasing bioavailability and reducing systemic toxicity. Exploits the Enhanced Permeability and Retention (EPR) effect in tumors, where leaky endothelial gaps allow nanoparticle accumulation (e.g., Paclitaxel-loaded albumin nanoparticles, liposomal doxorubicin).
• Cosmetics: Zinc oxide ($ZnO$) and titanium oxide ($TiO_2$) nanoparticles provide UV protection in sunscreens. Liposomes and nanoemulsions enhance skin penetration of vitamins and essential oils.
• Agriculture & Food Packaging: Nano-pesticides enable precision farming with lower chemical exposure. Nanomaterials in packaging extend food preservation. Silver and iron nanoparticles disinfect livestock.
• Textiles: Nanomaterials impart stain/water repellence, wrinkle-free features, fire retardancy, and electrical conductivity to fibers.
• Nanobiosensors: Low-cost, point-of-care diagnostic devices for bedside or field detection of biological biomarkers, utilizing "Lab on a Chip" microfluidic technology.

• Reductionist Approach: Studying organisms by breaking them down from higher-level descriptions (whole animal/plant) to tissues, cells, organelles, and molecules (DNA, proteins).
• Integrative Approach: Collecting multi-level data to build computer models of tissues and metabolic pathways (Bioinformatics, Systems Biology).
• Synthetic Biology: Designing and constructing new biological parts, devices, and systems, or re-designing existing natural biological systems. Requires standardized biological parts and rules of composition.

Top-Down vs. Bottom-Up Synthetic Biology

• Top-Down Approach: Reconstitution and stripping down of existing forms of life to create simplified genomes or metabolic networks.
• Bottom-Up Approach: Creating entirely new forms of life from non-living chemical constituents (e.g., chemical synthesis of a fully functional yeast chromosome).