2. Domains of Life Dr Thirunahari Ugandhar
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Domains of Life
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2. Domains of Life Dr Thirunahari Ugandhar
- 1. The Systematic position of microorganisms in the universal tree of life. by Dr. Thirunahari Ugandhar Associate Prof of Botany Department of Botany Kakatiya Govt College (A) Hanamkonda
- 3. The Domains of Life
- 6. • The Tree of Life and Exploration of Microbial Diversity • The tree of life, or phylogenetic tree, is a diagram that represents evolutionary relationships among various forms of life, including plants, animals, and microorganisms. • Key Concepts of the Tree of Life • 1. Domains of Life • The highest rank in the phylogenetic tree includes three domains: Bacteria: Prokaryotic cells lacking membrane-enclosed nuclei and organelles. • Archaea: Prokaryotic cells with unique genetic and biochemical traits, many of which are extremophiles. • Eukarya: Eukaryotic organisms with membrane-enclosed nuclei and organelles, including unicellular microbes and multicellular plants, animals, fungi, and protists. • 2. Taxonomic Hierarchy • Domains are subdivided into Kingdom, Phylum, Class, Order, Family, Genus, and Species, forming a hierarchical classification system
- 7. • 3. Historical Perspective • Initially, life was classified into five kingdoms: • Animals, Plants, Fungi, Protists, and Bacteria. • American microbiologist Carl Woese introduced the three-domain system in the 1970s based on genetic relationships rather than physical traits. • Woese used the 16S and 18S rRNA for phylogenetic analysis, revolutionizing the understanding of life's evolutionary relationships. • 4. Eukarya Domain • Combines unicellular and multicellular organisms, including plants and animals. • Microbial groups in Eukarya are more diverse than in the other domains.
- 8. • 5. Archaea • Defined as a new domain by Woese, Archaea includes organisms that thrive in extreme environments (e.g., high temperature, salinity, or acidity), called extremophiles. • 6. Diversity in Microbial Groups • Microbes dominate the tree of life with extraordinary variety compared to plants and animals.
- 10. Exploration of Microbial Diversity: Culture-Dependent Methods • Microbial diversity is investigated using various approaches, with culture-dependent methods being a cornerstone technique. • These methods involve isolating and cultivating microorganisms under controlled laboratory conditions, allowing researchers to study their morphology, physiology, and biochemical properties. Key steps in culture-dependent methods include: 1. Sample Collection: Gathering environmental or clinical samples containing microbial communities. 2. Media Preparation: Using selective or differential growth media tailored to target specific microbial groups. 3. Culturing: Incubating samples under specific conditions (temperature, pH, oxygen levels) to promote microbial growth. 4. Identification: Employing microscopic, biochemical, or molecular techniques to classify the cultured microorganisms.
- 11. Exploration of Microbial Diversity: Culture- Dependent Methods
- 12. • 3. Advantages: • Isolation of specific microbes for further study. • Identification of metabolic traits and antibiotic production. • Enables experimental studies on microbial physiology and genetics. • 4. Limitations: • Many microbes are unculturable under standard laboratory conditions, leading to an underestimation of diversity. • Certain microbes require complex or unknown growth conditions. • 5. Examples of Media Types: • General Media: Nutrient agar for non-selective growth. • Selective Media: Contains specific agents to encourage the growth of certain microbes while inhibiting others. • Differential Media: Helps distinguish between microbial types based on biochemical reactions (e.g., blood agar).
- 13. • Applications of Culture-Dependent Methods in Microbial Diversity 1. Discovery of Novel Antibiotics and Enzymes: Culturing diverse microbes helps identify new bioactive compounds and enzymes for medical and industrial applications. 2. Industrial Fermentation Processes: Utilized in producing food products (e.g., yogurt, cheese), biofuels, and pharmaceuticals through microbial fermentation. 3. Environmental Monitoring and Bioremediation Studies: Aids in isolating microbes capable of breaking down pollutants or monitoring environmental health. 4. Complementary Role in Microbial Research: Culture-dependent methods remain fundamental in microbial studies, complementing molecular and culture-independent approaches to reveal diversity and ecological roles.