Introduction to General Microbiology

General Microbiology

• Microbes include bacteria, fungi, protozoa, algae, and viruses
• Microbes affect our lives

Positive Contributions of Microbes

• In food production, specific bacteria are used, such as Lactococcus lactis
• Yogurt is produced by fermenting milk with bacteria like Lactobacillus bulgaricus and Streptococcus thermophilus
• Yeast (Saccharomyces cerevisiae) helps bread dough rise by producing carbon dioxide
• Alcoholic beverages are produced by fermentation using yeast
• Soy sauce is created using molds such as Aspergillus oryzae
• In medicine and health, Penicillium mold produces penicillin, an early antibiotic
• Engineered microbes help make proteins for vaccines; an example is Escherichia coli
• In environmental roles, soil microbes like Rhizobium convert nitrogen gas into a usable form for plants
• Microbes also decompose organic waste, recycling nutrients into the ecosystem

Microbiome & Normal/Transient Microbiota

• Microbiome signifies the community of microbes living in or on bodies
• Example gut microbiome's bacteria such as Bacteroides and Firmicutes are essential for digestion and immune system function
• Normal Microbiota are microbes naturally found in and on the body, providing benefits
• Staphylococcus epidermidis skin bacteria helps protect against harmful microbes
• Transient Microbiota are microbes that temporarily reside in the body
• E. coli from contaminated food can temporarily colonize the intestines

Historical and Modern Perspectives on Microbes

• Microbes are often wrongly associated only with disease, most are beneficial and essential
• During World War I, Chaim Weizmann used bacteria to produce acetone for gunpowder
• Microbes like cyanobacteria conduct photosynthesis, producing oxygen and forming the base of aquatic food chain
• Cyanobacteria produce nearly 50% of oxygen

The Human Microbiome

• The microbiome refers to the community of microbes living in and on the human body
• Escherichia coli in the gut aids digestion
• Bacteria synthesize vitamins, like Vitamin K and B Vitamins
• Microbes help the immune system recognize harmful vs. harmless invaders
• Microbial exposure begins in the womb, with newborns receiving microbes during delivery
• Microbes acquired after birth are from ingested food, and the environment

Microbial Growth

• Microbes thrive in environments suited to their needs
• Gut microbes flourish in nutrient-rich areas
• Skin thrives survive in acidic, cooler conditions, while gut microbes prefer warm, slightly basic environments
• Disruptions in gut microbiota have been linked to diseases like diabetes and inflammatory bowel disease
• Studying plant microbiomes helps develop more sustainable agriculture practices
• Traditional view saw microbes as harmful, but most are harmless beneficial
• A small percentage of microbes are pathogenic

Microbial ubiquity

• Microorganisms are ubiquitous in environments such as soil, oceans, hot springs, and the human body

Naming and Classifying Microorganisms

• System of nomenclature was established in 1735 by Carolus Linnaeus
• Nomenclature gives organisms two names:
  • Genus is the first name and is always capitalized
  • Specific epithet is the species name, follows the genus, and isn’t capitalized
• An organism is referenced using both genus and specific epithet, which are italicized

Types of Microorganisms

• Types include Bacteria, Fungi, Protozoa, Algae and Viruses,
• Antibiotics can be used to treat bacterial infections but have no effect on viruses or other microbes
• Bacteria are unicellular organisms classified as prokaryotes, their genetic material is not enclosed in a nuclear membrane
• Bacillus: Rod-shaped, Coccus: Spherical-shaped, Spiral: Corkscrew-shaped

Bacteria Reproduction and Harmful/Helpful Examples

• Bacteria reproduce through binary fission
• Lactobacillus doubles quickly during yogurt fermentation
• Bacteria can be Organic, Photosynthetic, or Inorganic for nutrition
• Flagella allow mobility
• Harmful bacteria such as Clostridium botulinum cause botulism
• Helpful bacteria such as Lactobacillus acidophilus aids digestion

Archaea

• Archaea are prokaryotes similar to bacteria
• They lack peptidoglycan in their cell walls
• Methanogens produce methane in oxygen-free environments
• Halophiles thrive in salty areas
• Extreme Thermophiles live in hot springs
• Archaea contributes to biotechnology

Fungi

• Fungi are eukaryotes with a nucleus, can be unicellular (yeast) or multicellular (mold, mushrooms)
• Composed of chitin, unlike bacterial peptidoglycan
• Reproduction is sexual or asexual.
• Example decomposition via molds on dead plants and animals

Protozoa

• Protozoa are unicellular eukaryotic microbes that move using pseudopods, cilia, or flagella
• Nutrition is from absorbing or ingesting organic compounds
• Some are photosynthetic, e.g. (Euglena)

Algae, Viruses & Multicellular Animal Parasites

• Algae are photosynthetic eukaryotes that produce oxygen and carbohydrates
• Habitats are in freshwater, saltwater, and soil
• Viruses are acellular entities made of DNA or RNA surrounded by a protein coat
• They reproduce inside host cells, with a core of DNA or RNA, a protein coat, and envelope
• Multicellular Animal Parasites live part of their life cycles as microscopic forms

Classification

• Microbial classification system devised by Carl Woese
• System includes Bacteria, Archaea, and Eukarya
• Bacteria cell walls contain peptidoglycan
• Archaea cell walls, if present, lack peptidoglycan
• Eukarya includes protists, fungi, plants, and animals

Human Welfare & Element Recycling

• Microbes includes beneficial activities
• Vast majority of microbes benefit humans, animals, and plants
• Biotechnology companies use bacterial enzymes to break down plant cellulose so that yeast can metabolize
• Microbes produce alternative fuels like methane and ethanol to generate electricity and power vehicles
• Bacteria decompose organic waste, recycle vital elements between soil and the atmosphere
• Bacteria and fungi decompose organic waste and dead organisms, returning carbon dioxide and algae
• Atmospheric nitrogen converted by bacteria

Sewage Treatment, Bioremediation & Insect Pest Control

• Society's awareness emphasizes responsibility to recycle water, and sewage includes:
  • Human excrement and waste
• Plants remove materials, eliminate harmful bugs and combine processes and microbes
• Sewage treatment process involves liquid and organic materials converted by bacteria into Carbon dioxide, Nitrates, Phosphates etc
• Scientists use microbes to clean toxic wastes from processes since 1988, to:
  • Use pollutants as energy
  • Enzymes to breakdown harmful toxins
• Bioremediation has been used in underground, oil spills

Insecticides and Recombinant Biotechnology

• Bacillus thuringiensis used in pest control
• Bacillus thuringiensis bacteria produces protein crystals toxic, inserted toxin gene
• Recombinant DNA has revolutionized biotechnology

DNA Technology

• Production of natural proteins, vaccines,
• Gene therapy of inserted/replaced human cells
• Control crop-damaging insects to protect fruits
• Agricultural applications of recombinant DNA technology improves appearance and shelf life, droughts
• Recombinant DNA offers resistance to insects and microbial diseases and increased high temperatures

Microbes and Human Disease

• Microbes can be beneficial and harmful
• Resistance, the body's ability to ward off diseases, depends on physical barriers such as external support antibiotics
• Biofilms are complex aggregates of microbes attached to solids
• Biofilm protect from harmful microbes
• Biofilm resistance to antibiotics, due to the protective barrier

Infectious Diseases

• Occur with life cycle within host, Post-World War II Malaria expected to be eradicated by DDT
• Pertussis (whooping cough) vaccine decreased disease
• Sanitation measures prevent cholera transmission
• Emerging Infectious Diseases affect Malaria, Pertussis, Cholera
• Reemerging/Emerging Diseases infectious diseases reemerge/increase
• Evolutionary changes, the spread, increasing exposure

Factors that Contribute to EIDs

• The evolutionary changes of organisms like, (Vibrio cholerae)
• Spread of known diseases to others
• High exposure
• Changes pathogens (Powassan)