Microbiology and Parasitology: An Overview

Microbiology and Parasitology Overview

• Microbiology involves studying microorganisms.
• Microorganisms are too small to be seen unaided.
• Microbiology focuses on understanding microscopic organisms and applying this knowledge to benefit humankind and Earth.
• Parasitology is the study of parasitic organisms, their biology, and their interactions with hosts and the environment.
• Human (or medical) parasitology focuses on parasites of medical importance, including protozoology, helminthology, and entomology.
• Parasitology is important in clinical and preventative medicine in the context of understanding parasitic diseases.

Microbiology as a Science

• Microbiology is a basic biological science, using and developing tools to investigate fundamental life processes.
• Microbial cells share characteristics with cells of multicellular organisms and can achieve extremely high densities.

Fields of Microbiology

• Microbial physiology examines the functions of microbial cell structures, growth, and metabolism in living organisms, encompassing bacteria, fungi, viruses, and parasites.
• Microbial genetics, a subject area in microbiology and genetic engineering, involves the study of microorganisms for different purposes.
• This study utilizes either a microorganism's entire genome or specific genes.
• Microbial biochemistry includes biochemical reactions involved in microbial growth, pathogenesis, and host interactions; includes the study of microbial cell structure, metabolism, and interactions with proteins, fatty acids, and nucleic acids.
• Microbiology is an applied biological science at the center of human/veterinary medicine, agriculture, and industry.
• Many microorganisms are essential to soil fertility and domestic animal welfare.
• Large-scale industrial processes leverage microbes for antibiotic and human protein production.
• Medical microbiology applies microbiology to medicine for the diagnosis, treatment, and prevention of diseases caused by microorganisms.
• This field also investigates clinical applications of microbes to improve health.
• Agricultural/soil microbiology examines microorganisms in soil, their functions, and their effects on soil properties, focusing on bacteria, actinomycetes, fungi, algae, and protozoa.
• Industrial microbiology uses microorganisms in industrial processes to produce medicines, cleaning agents, fuels, electricity, and foods.
• Aquatic microbiology studies microbes in fresh and saltwater systems, including microscopic plants, animals, bacteria, viruses, and fungi and their interactions.

Impact of Microorganisms on Humans

• Cyanobacteria, or blue-green algae, are among Earth's earliest organisms that produce oxygen via photosynthesis fixing CO2 in water.
• RNA and DNA analysis indicates that all photosynthetic organisms derive the ability from cyanobacteria through endosymbiosis
• Chloroplasts are what remain after engulfing cyanobacteria.
• Microorganisms, though tiny, account for most of Earth's biomass
• Humans, plants and animals depend on microbial activity for nutrient cycling etc.
• Humans and microorganisms share an intimate relationship, with over 90% of the body's cells being associated with microbes.

Historical Roots of Microbiology

• Robert Hooke (1635–1703) was a mathematician, historian, and microscopist.
• Hooke's "Micrographia" (1665) was the first book dedicated to microscopic observations
• Hooke's book included illustrations of molds, marking the first known description of microorganisms.
• Antoni van Leeuwenhoek (1632–1723) used simple microscopes to examine natural substances and discovered Bacteria in 1676.
• Ferdinand Cohn (1828–1898), a botanist and microscopist, studied unicellular algae and bacteria and their heat resistance
• Cohn found that some bacteria form endospores.
• Cohn described the life cycle of Bacillus and showed that boiling killed vegetative cells, but not endospores and founded a scientific journal of plant and microbial biology.

Disproving Spontaneous Generation

• The theory of spontaneous generation stated that living organisms could arise from non-living matter.
• Believed for almost 2000 years based on observations without controlled experiments

Spontaneous Generation Examples

• Nile River floods lead to frogs appearing, leading to the conclusion that muddy soil created the frogs.
• Medieval grain stored in leaking barns appeared to produce mice.
• Sewage in cities seemed to turn into rats in cities in Europe that had an outbreak of Bubonic Plague
• Rotting meat appeared to turn into flies.

Redi's Experiment (1668)

• Francesco Redi used open and closed flasks with meat to test whether rotten meat turns into flies.
• He observed which flasks developed maggots.
• No maggots appeared in closed flasks, disproving spontaneous generation for larger organisms.

John Needham's Experiment (1745)

• John Needham showed that microorganisms flourished in soups exposed to air.
• He suggested a "life force" in inorganic molecules caused spontaneous generation.
• His experiments seemed to support spontaneous generation
• People at the time failed to realize that his soups were already contaminated.
• The soups also did not boil long enough to kill any microbes.

Lazzaro Spallanzani's Experiment (1765)

• Lazzaro Spallanzani boiled soups for an hour and sealed the containers.
• The soups remained clear until the seals were broken, disproving spontaneous generation, however, spontaneous generation remained the theory.
• The sealed Vials, according to critics, did not allow air for organisms to survive.

Louis Pasteur: How Microbes Arise

• By 1860, the Paris Academy of Sciences offered a prize to resolve the spontaneous generation debate.
• Louis Pasteur won the prize in 1864 with an experiment disproving spontaneous generation in microscopic organisms.
• Louis Pasteur hypothesized microbes originated from organisms in the air, not the air itself.
• He put broth in special S-shaped flasks, boiled them, and placed them in different locations.

Pasteur's Experiment Steps

• S-shaped or swan-necked flask was filled with broth.
• The special shape was to trap any dust or bacteria.
• The flasks were boiled to kill microbes.
• The flasks did not turn cloudy afterward and no microbes were found unless they were left at various locations and dust collected on the necks.
• Pasteur's S-shaped flask kept microbes out, proving microbes only come from other microbes; This is called biogenesis.
• Discoveries from pasteurs experiments included microbial life being destroyed by heat/pasteurization, and aseptic techniques (preventing contamination by unwanted microorganisms)

Koch's Postulates and Pure Culture Microbiology

• Robert Koch (1843–1910) studied anthrax, caused by Bacillus anthracis and used special stains to see it in the blood of animals that succumbed to the disease.

Koch's Postulates

• The suspected pathogen must be in all cases of the disease, not in healthy animals
• The suspected pathogen must be grown in a pure culture.
• Cells from the pure culture of the suspected pathogens must cause disease in healthy animals
• The suspected pathogen must be reisolated and shown to be the same as the original.

Important figures from The Rise of Microbial Diversity

• Robert Koch first cultivated bacteria on solid media; he initially used potato slices, where gelatin was used as a solidifying agent for various nutrients
• Walter Hesse, associate of Koch, first used agar in bacterial culture recommended by his wife Fannie (using agar to solidify fruit jelly) desirable as a gelling agent for microbial culture media.
• Richard Petri developed the Petri dishes, transparent double-sided dishes.
• Significance of Pure Cultures is the classification of microbes as varieties, strains, kinds, or other labels
• Martinus Beijerinck (1851–1931) formulated the Enrichment culture technique where microorganisms are isolated from natural samples adjusting nutrient to favor a particular metabolic group.
• He isolated the aerobic nitrogen-fixing bacterium Azotobacter from the soil; as well as other pure cultures from soil, as well as isolated the tobacoo mosaic disease caused by a virus.
• Sergei Winogradsky proposed chemolithotrophy by the oxidation of inorganic compunds; and isolates the nitrogen fixing bacterum of Clostridium pasteurianum

Where Did Life Come From?

• Primitive Earth differed greatly from Earth today.
• Abundant energy sources and time for simple molecules to made.
• Alexander Oparin published 'The Origin of Life' in Nov. 1923 stating that the first organisms to emerge in the anaerobic envi. of the earth, however these were heterotrophic bacteria.
• Stanley Miller (1953) tested the Oparin hypothesis and showed organic compounds could be synthesized under primitive conditions

Important figures from Miller's Experiment and Alternate Theories

• Miller showed that tarry hydrocarbons formed, as well as amino acids, and lactate & formate
• Miller’s atmosphere has been shown not to be correct
• Volcanic activity occurred that was full of fumarolic gases, volcanic activity, and heat.
• Gases included CO2, N2, SO2, H2S
• UV light was intense
• Organic compounds synthesized, and came brrought by meteorites
• Mineral surfaces as catalyzers, or carbonaceous chondrites

Panspermia

• Some believe that life on Earth originated through seeds in meteors.
• EX. Deinococcus radiodurans

Abiotic Chemical Evolution - Origin of First Cells

• Synthesis and accumulation
• Polymerization
• Aggregation
• Origin of heredity
• Protocells evolved into protobionts which were self-organized, ordered with sphericall collection as a stepping stone for origins of life
• From these evolutions sprung the Last Universal Common Ancestor (LUCA) or progenotes in which there was a combination and symbiosis; these were also the believed origin of all life on Earth
• Cell Membranes of a Eukarya and Bacteria are similar with similar linked acids, Archaea is different and there is evolutionary theory.

Extent of Microbial Life Based on Statistics:

• 66% Located in Marine subsurface
• 26% Located in Terrestrial Subsurface
• 4.8% Located in Surface soils
• 2.2 % Located in the Oceans
• and the rest are located in other habitats.