Biology 145 Microorganisms lecture 1

Microorganisms in Human Life

• Microorganisms play essential roles in various fields of human life, including:

  • Food Production:

    • Yogurt: Produced through bacterial fermentation of milk by lactobacillus bulgaricus and streptococcus thermophilus, which convert lactose into lactic acid, giving it a tangy flavor and thick texture.

    • Beer and Wine: Fermentation by yeasts like saccharomyces cerevisiae produces alcohol and carbon dioxide, contributing to the carbonation and alcohol content of beverages.

    • Cheese: Varieties are created using bacteria and sometimes fungi that influence flavor and texture.

    • Bread: Yeast ferments sugars, generating carbon dioxide that leavens the dough and creates a soft texture.

Wastewater Treatment and Bioremediation

• Microbial Applications:

  • Microbes degrade organic waste in sewage and polluted environments, metabolizing harmful compounds and cleaning up contaminants like oil spills.

  • Biotowers:

    • Sewage is sprayed over structures called biotowers, providing surfaces for microbial attachment and biofilm formation that enhance waste breakdown.

  • Filtration and Chlorination:

    • Treated sewage undergoes filtration to remove solid waste, followed by chlorination to disinfect and kill pathogens, ensuring public health.

Serendipity in Science

• Definition:

  • Serendipity refers to unexpected discoveries made by chance, particularly important in scientific exploration.

• Example - Alexander Fleming:

  • Discovered penicillin when observing that the mold Penicillium notatum inhibited bacterial growth in a petri dish, leading to the first antibiotic.

• Impact of Penicillin:

  • Effectively targets bacterial cell walls, particularly in gram-positive bacteria, revolutionizing medicine and saving millions of lives.

Antibiotic Development

• **Predecessors to Penicillin: **

  • Mercuric compounds and sulfonamides were early antimicrobials preceding penicillin.

• Penicillin’s Significance:

  • The first naturally occurring antibiotic, its mass production during WWII saved countless lives and inspired the search for more antibiotics from natural sources.

• Mechanism of Action:

  • Inhibits peptidoglycan synthesis, leading to the lysis of bacterial cells, primarily effective against gram-positive bacteria.

Challenges with Antibiotics

• Antibiotic Resistance:

  • Overuse and misuse have accelerated resistance in bacteria, leading to strains like MRSA (Methicillin-resistant Staphylococcus aureus).

  • The need for continued research into novel antibiotics and alternative treatments remains critical.

Modern Antibiotic Production

• Most antibiotics are derived from naturally occurring compounds, with the Streptomyces genus being a primary source of antibacterial agents.

Types of Antibiotics

• Broad-spectrum: Effective against a wide range of bacteria (e.g., tetracyclines).

• Narrow-spectrum: Target specific bacteria (e.g., penicillin).

Bioremediation and Environmental Applications

• Microbial Roles:

  • Bacteria like Pseudomonas putida and Alcanivorax are involved in breaking down pollutants, including oil spills and toxic substances.

• Biotechnology:

  • Engineered bacteria produce therapeutic proteins (e.g., insulin) and probiotics improve gut health.

Unique Bacterial Characteristics

• Colorful Bacteria:

  • Microbial growth in a Winogradsky column illustrates vibrant colors due to different metabolic functions:

    • Green: Cyanobacteria (photosynthetic).

    • Purple/Pink: Sulfur bacteria.

    • Black: Sulfate-reducing bacteria.

Bioluminescence and Complex Structures

• Some bacteria exhibit bioluminescence, beneficial for various ecological interactions.

• Examples include Myxobacteria: known for forming fruiting bodies through social behavior and cellular communication.

Bioremediation Examples

• Exxon Valdez Oil Spill:

  • Hydrocarbon-degrading bacteria were used to metabolize oil into harmless substances, aiding in environmental recovery.

• Use of Bacillus thuringiensis:

  • Employed as a natural insecticide, with genetically modified crops incorporating its toxin for pest resistance.

Infectious Diseases and Challenges

• Bacteria can cause serious illnesses, such as necrotizing fasciitis and pneumonia, often leading to severe health issues.

• Antibiotic resistance remains a major public health threat, requiring attention to responsible antibiotic use and development of new treatments.

Global Impact of Antibiotics

• Access to antibiotics and healthcare affects low-resource regions disproportionately, promoting initiatives to enhance stewardship and prevent misuse.

Future in Microbiology

• Career Opportunities:

  • Diverse roles available in healthcare, pharmaceuticals, biotechnology, and environmental sciences.

• Education Paths:

  • Typically involves degrees in microbiology or related fields, with advanced education for specialized areas.

Addressing Global Problems

• Microbiologists confront pressing issues like antibiotic resistance, sustainable agriculture, and medical technology advancement.