Exam 4 Notes Updated PDF

📖 Exam 4 Notes Updated Created @November 5, 2024 12:01 PM Class Micro Reviewed 📌 SUMMARY: Study Guide: Biochemical Cycling & Soil Describe the roles/interactions/symbio...

📖 Exam 4 Notes Updated Created @November 5, 2024 12:01 PM Class Micro Reviewed 📌 SUMMARY: Study Guide: Biochemical Cycling & Soil Describe the roles/interactions/symbiotic relationships discussed in lecture that microbes play in ecosystems; please include specific examples. Nitrogen Fixation: Some bacteria (e.g., Rhizobium in legumes) form symbiotic relationships with plants by fixing atmospheric nitrogen, which benefits plant growth while receiving nutrients in return. Carbon Cycling: Decomposing bacteria and fungi break down organic material, releasing carbon dioxide (CO₂) back into the environment, aiding in carbon cycling. Mycorrhizal Fungi: Fungi associated with plant roots assist in nutrient and water absorption, improving plant resilience and growth. Discuss the reasons that soil microbial communities are not well understood. Exam 4 Notes Updated 1  Diversity and Complexity: Soil contains a vast number of microbial species, many of which are unculturable in lab settings. Environmental Variability: Microbial communities fluctuate with changes in moisture, temperature, and nutrient availability, making it hard to replicate and study these conditions. Symbiosis and Dependency: Many microbes depend on interactions with other organisms, making isolation and study of individual species challenging. Describe the various environmental conditions found in soils, including the different types of soils and the types (i.e., chemolithotrophs) of microorganisms found in them. Soil Types and Conditions: Organic-Rich Soils: Support heterotrophs and decomposers due to the abundance of organic material. Mineral Soils: Favor chemolithotrophs, which use inorganic compounds (e.g., ammonia) for energy. Moisture Levels: Surface soils with oxygen support aerobic bacteria, while waterlogged soils favor anaerobic bacteria. pH and Temperature: Influence microbial growth, with some microbes adapted to extreme conditions in specialized soils. Discuss the specific roles that microbes have in the nitrogen cycle. Nitrogen Fixation: Bacteria like Rhizobium convert atmospheric nitrogen (N₂) to ammonia (NH₃), providing a usable form of nitrogen for plants. Nitrification: Ammonia is converted to nitrite (NO₂⁻) by Nitrosomonas, and then to nitrate (NO₃⁻) by Nitrobacter, making nitrogen available for plant uptake. Denitrification: Anaerobic bacteria (e.g., Pseudomonas) reduce nitrate back to nitrogen gas (N₂), releasing it into the atmosphere and completing the cycle. Food Exam 4 Notes Updated 2  Discuss the interaction of intrinsic (food-related) and extrinsic (environmental) factors related to food spoilage. Intrinsic Factors: Nutrient Composition: High-protein and high-lipid foods spoil quickly due to microbial growth, as seen in meats and dairy. Water Activity: Foods with higher water content spoil faster because microbes require water to grow (e.g., fresh milk vs. powdered milk). pH: Foods with low pH (acidic foods) inhibit microbial growth (e.g., citrus fruits), while neutral or slightly alkaline foods are more prone to spoilage. Oxidation-Reduction Potential: Aerobic microbes thrive in high-oxygen foods, while anaerobes grow in low-oxygen or anaerobic conditions. Extrinsic Factors: Temperature: Lower temperatures slow microbial growth, prolonging food shelf life (e.g., refrigeration), while room temperature encourages rapid spoilage. Humidity: High humidity levels promote spoilage by encouraging microbial activity on the surface. Pre-existing Microbial Load: The initial number of microbes on food influences the spoilage rate; foods with more microbes initially spoil faster. Describe the various physical, chemical, and biological processes used to preserve food. Physical Methods: Temperature Control: Refrigeration slows down microbial growth, while freezing nearly stops it. Heat treatments like pasteurization kill pathogens (e.g., milk). Dehydration: Reduces water activity, inhibiting microbial growth (e.g., dried fruits). Chemical Methods: Exam 4 Notes Updated 3  Salting and Sugaring: Creates a high-osmolarity environment that dehydrates microbes. Acidification: Adding acids (e.g., vinegar) lowers pH, making the environment inhospitable for many microbes. Biological Methods: Fermentation: Microorganisms (e.g., Lactobacillus) produce acids that preserve food naturally (e.g., yogurt, sauerkraut). Preservative Microbes: Lactic acid bacteria are used to inhibit spoilage organisms in certain foods. Differentiate between food infections and food intoxications & give an example of each that was discussed in lecture. Food Infections: Caused by consuming food contaminated with pathogenic microbes that then colonize the host. Example: Salmonella infection from undercooked poultry, which requires a high infectious dose (about 10,000 cells). Food Intoxications: Result from ingesting toxins produced by microbes in food before consumption, not by the microbes themselves. Example: Staphylococcus aureus intoxication occurs when S. aureus grows on food left at unsafe temperatures, producing toxins that cause rapid onset of nausea and vomiting. Discuss the detection of disease-causing organisms in food. Traditional Culture Techniques: Involve culturing food samples on selective media to identify pathogens based on their colony characteristics. Rapid Detection Methods: Include immunoassays (e.g., ELISA) to detect specific pathogens or PCR-based methods to amplify pathogen DNA, providing faster and often more accurate results. Hurdles in Detection: Pathogens may be present in low numbers, making detection challenging. Additionally, some pathogens require specific growth conditions, and their detection can be inhibited by other microbial flora. Exam 4 Notes Updated 4  Describe foods discussed in lecture that are made with the aid of microorganisms and indicate the types of microorganisms used in their production. Cheese: Produced by lactic acid bacteria (e.g., Lactococcus lactis), which ferment lactose, causing milk to curdle and form cheese. Yogurt: Created by fermenting milk with bacteria like Streptococcus thermophilus and Lactobacillus bulgaricus, which produce lactic acid, giving yogurt its texture and tangy flavor. Wine and Beer: Made with Saccharomyces cerevisiae (yeast) that ferments sugars to produce ethanol and carbon dioxide. Sauerkraut: Fermentation of cabbage by lactic acid bacteria, including Leuconostoc species, creates the sour taste and preserves the food. What are probiotics? What are the pro/cons and limitations of their use? Probiotics: Live microorganisms that, when consumed in adequate amounts, provide health benefits by improving gut flora balance. Pros: May aid digestion and improve gut health. Can help prevent certain infections by competing with pathogens. Cons: Not all probiotics survive stomach acid to reach the gut. Some people may experience mild digestive discomfort. Limitations: Not all probiotics work for every individual or condition. The benefits can be strain-specific, and effects may vary widely based on the individual’s existing gut microbiota. Industrial/Waste Water & Bioremediation Exam 4 Notes Updated 5  Discuss the sources of microorganisms for use in industrial microbiology. Natural Environments: Soil and water ecosystems are major sources, as they contain a wide variety of microbes with diverse metabolic capabilities. Laboratory Cultures: Strains are often isolated and then optimized in laboratories to enhance production of desired products. Genetic Engineering: Microbes are genetically modified to improve efficiency in industrial processes, such as producing enzymes or biochemicals on a larger scale. Discuss the wastewater treatment and water purification & their importance. Wastewater Treatment: Primary Treatment: Physical processes like sedimentation remove large particles and organic matter. Secondary Treatment: Microbial processes, including aerobic digestion, break down organic pollutants, reducing biological oxygen demand (BOD). Tertiary Treatment: Involves additional filtration, chemical treatments, and disinfection (e.g., chlorination) to remove remaining pathogens and contaminants. Water Purification: Purification ensures safe drinking water by removing microbes, toxins, and chemicals through filtration, chlorination, and sometimes UV treatment. Importance: Prevents waterborne diseases, ensures safe reuse of water in ecosystems, and maintains public health. Describe the major products or uses of industrial microbiology. Enzymes: Microbial enzymes like amylase and protease are used in detergents, food processing, and biofuels. Antibiotics: Produced by microbes such as Streptomyces, used to treat bacterial infections. Exam 4 Notes Updated 6  Biofuels: Ethanol produced by yeast fermentation and biogas generated by anaerobic bacteria contribute to sustainable energy solutions. *Fermented Foods**: Lactic acid bacteria are used to produce foods like yogurt, cheese, and fermented vegetables. Discuss the manipulation of microorganisms and the environment to control biodegradation. Bioremediation: The use of microorganisms to break down pollutants in the environment, such as oil spills or industrial waste. Environmental Manipulation: Nutrient Addition: Adding nutrients like nitrogen and phosphorus stimulates microbial growth to enhance pollutant breakdown. Controlled Conditions: Temperature, pH, and moisture are managed to optimize microbial degradation of contaminants. Genetic Engineering: Some microbes are engineered to degrade specific pollutants more efficiently (e.g., hydrocarbon-degrading bacteria for oil spills). Presentation-Based Notes for Potential Test Questions Pseudomonas Pseudomonas species are versatile bacteria found in various environments, including soil and water. Known for resilience and ability to survive in harsh conditions. Produces biofilms, contributing to antibiotic and environmental stress resistance. E. Coli in Municipal Water E. coli contamination often linked to sewage leaks or agricultural runoff. Detection methods: water testing and rapid detection to prevent outbreaks. Preventive measures include water purification processes and regular testing. Exam 4 Notes Updated 7  Salmonella and Pet Chickens Salmonella can be transmitted to humans through contact with pet chickens. Often present on feathers, in droppings, and on contaminated surfaces. Prevention includes proper handwashing, avoiding contact with the face after handling chickens, and safe pet practices. Bear Meat and Salmonella Bear meat and other wild game can harbor Salmonella due to lack of controlled processing. Risk of infection increases if the meat is not thoroughly cooked. Important precautions include cooking meat to the recommended internal temperature and practicing safe handling. Gummy Poisoning Highlights contamination risks in processed foods, specifically gummy candies. Contamination sources may include improper handling during manufacturing, bacterial growth, or chemical residues. Emphasizes the importance of safe processing practices and monitoring in food production facilities. Salmonella and Cantaloupe Salmonella contamination in cantaloupe can occur during growth, harvest, or processing. Factors include contaminated irrigation water, contact with soil, and improper handling. Preventive measures include proper washing, storage, and handling practices for produce to avoid cross-contamination. Restaurant-Based Salmonella Case Exam 4 Notes Updated 8  Outbreaks in restaurants are often linked to poor food handling practices, cross-contamination, or insufficient cooking. Critical control points include temperature control, regular handwashing, and safe food storage. Emphasizes the importance of food safety training and adherence to health guidelines in the food industry. Class Notes: Recall Notes Write 3+ Qs to test Future You Exam 4 Notes Updated 9