L12 Flashcards
What are the levels of taxonomic classification?
Bacteria, proteobacteria, gammaproteobacteria, enterobacteriales, escherichia, escherichia coli, strain K-12
What is the bacterial phyla?
80+ phyla, distinguished based on 16s ribosomal RNA. 90% of genera come from four phyla ; proteobacteria, actinobacteria, firmicutes, bacteriodetes. Proteobacteria is the largest
What is the proteobacteria phyla?
Largest and most metabolically diverse, different shapes, gram-negative bacteria. 6 classes : alpha, beta, gamma, delta, epsilon, zeta. Used in medicine, agriculture etc. horizontal gene flow important in shaping metabolic diversity.
What is an proteobacteria example?
E. coli gram-negative, gammaproteobacteria, facultative anaerobic, rod shaped. Inhabit intestinal tract, some pathogenic strains.
What is the firmicutes phylum?
Gram-positive, other than gram-negative mycoplasmas. Live in gut, form endospores. First colonisers of intestine of newborns. Genetic exchange is common and non-selective. Obligate aerobes of facultative or strict anaerobes.
What do some bacteria produce?
Endospores
What are endospores?
Survival structures, can survive metabolically inert state for decades, high resistance to temp, stresses, radiation. Most resistant bio structures, germinate to become vegetative cells when appropriate nutrients become available.
How do endospores form?
Bacterial chromosome is replicated, and cells divide asymmetrically. Mother cell engulfs the developing endospores then once development is complete it is released.
What are the steps of endospores formation? 1-3
While the chromosome is replicated, the nucleoid lengthens to form the axial filament. A sporulation septum forms at a point about a quarter of a cell length - polar septum. The large portion of the cell is called the mother cell which nourishes the developing endospore. The mother cell engulfs the developing endospore completely
What are the steps of endospores formation? 4-7
The developing endospore is surrounded by two cell membranes, its own and the mother cells. A layer of mureinm the cortex, is synthesised between two membranes. The developing endospore becomes surrounded by additional layers, the exosporium. The developing endospore synthesises dipicolinic acid. The mother cell lyses releasing the mature endospore.
How does position of endospore in mother cell differ?
Terminal endospores include clostridium tetani, central endospore Bacillus megaterium, subterminal endospore, bacillus subtilis.
How is endospore staining completed?
Bacteria stained with malachite green dye, bacteria are treated with steam to allow the green malachite green dye to penetrate the endospores coat, slide is rinsed. Counter stain of safranin.
What resulted do stained Bacillus megaterium show?
Vegetative cells (pink) endospores (green).
What resulted do stained Bacillus subtilis show?
Vegetative cells (pink) endospores (green)
What is the actinobacteria phylum?
Gram-positive, very morphologically diverse, in soil they breakdown plants and animal debris. Antibiotic producers. They are bacteria despite filamentous growth and sporulation. Some are pathogenic and cause infection in fish and humans.
What are the filamentous actinobacteria?
Streptomyces
What are the streptomyces?
Filamentous actinobacteria, 600+ species, grow at filament tips and branch. Result in compact, convoluted mycelium and colony. Primarily in soil microorganisms. Favour alkaline/neutral soil. Found in well drained soil. Produce many extracellular enzymes. 50% produce antibiotics. Large genomes.
What is the Cyanobacteria phylum?
Gram-negative photosynthetic bacteria, which harvest light energy and generate oxygen. Original producers of atmospheric oxygen. Release half of all oxygen in the air. Some are filamentous other unicellular. Blooms cause oxygen depletion. Some produce toxins, which can affect the organisms that feed on Cyanobacteria and the predators that feed on them. Cyanotoxins in drinking water may be a risk to humans.
