Chapter 1

What is microbiology Study of organisms too small to be seen by the unaided eye – Microorganisms Relatively simple in their construction, mostly unicellular No distinct tissues

The Importance of Microorganisms Microbes exceed every other groups of organisms Found everywhere (ubiquitous) – ice capped mountains, bottom of the ocean Air, water, soil Inside us – normal flora – gastrointestinal, genitourinary, respiratory tract, on the skin Source of nutrients, some carry out photosynthesis Unicellular algae – bottom of the food chain

Aquatic environments. Unicellular algae bottom of the food chain. Unicellular algae > tiny fish > large fish > shark. Algae are autotrophs. They use CO2 and water to make sugar. Soil microbes are involved in recycling chemical elements. Breakdown cellulose and release CO2. Making food products (yogurt, cheese, bread). Yeast + flour > dough

Small ball of dough -----large ball of dough Therapeutic substances – genetic engineering is used to force E. coli to make human insulin. Bioremediation – microbes are used to clean up chemical pollutants (oil spills) in the environment. Insecticide – BT toxin is sprayed on plants. Sewage treatment – breakdown organic matter to produce methane.

Harmful aspects Tuberculosis, Lyme disease Spoilage of food products. Milk ----- sour. Lactose --- acids.

Members of the microbial world Procaryotic cells – pre-nucleus DNA is not surrounded by a membrane Eucaryotic cell – true nucleus DNA is surrounded by a membrane

Classification of organisms 1969 Robert whittaker 5 kingdom system Classification based on Cell type - prokaryotic/eukaryotic Cellular organization – unicellular/multicellular Nutritional requirements – photosynthetic/nonphotosynthetic

Classification of organisms Prokaryotae (monera) – procaryotic organisms – bacteria Protista - protozoa Fungi – Yeasts and molds Plant – ferns, trees, flowering plants Animal – worms, insects, vertebrates

3 domains Ribosomal RNA sequence Archaea, Bacteria, Eukarya Bacteria – procaryotic Normal flora, pathogens Peptidoglycan

Archaea Procaryotic Unique ribosomal RNA sequence Unusual, extreme environments Salt lakes, dead sea Do not have peptidoglycan cell wall Pseudomurein No pathogenic species known

viruses Acellular Obligate intracellular parasites Either have DNA or RNA No plasma membrane, cytoplasm

History of microbiology 1665 Robert Hooke – plant materials (leaves and stems). Little boxes – cells. 1673 – 1723 Anton van Leeuwenhoek observed microbes under the microscope.

Discovery of Microorganisms Antony van Leeuwenhoek (1632-1723) first person to observe and describe microorganisms accurately Figure 1.3 (a)

Figure 1.3 (b) and (c)

Rain water, scrapings from his teeth. Called the microbes animalcules. Spontaneous generation theory – life could arise from nonliving matter. Decaying meat could give birth to maggots (larvae of flies)

The Conflict over Spontaneous Generation living organisms can develop from nonliving or decomposing matter Francesco Redi (1626-1697) disproved spontaneous generation for large animals showed that maggots on decaying meat came from fly eggs

Fine net No maggots

But could spontaneous generation be true for microorganisms? John Needham (1713-1781) his experiment: mutton broth in flasks  boiled sealed results: broth became cloudy and contained microorganisms Lazzaro Spallanzani (1729-1799) broth in flasks sealed  boiled results: no growth of microorganisms

Needham 1745

Louis Pasteur (1822-1895) his experiments placed nutrient solution in flasks created flasks with long, curved necks boiled the solutions left flasks exposed to air results: no growth of microorganisms

CO 01

Pasteur’s experiment S shaped curve S shaped curve S shaped curve

Germ theory of disease Belief microbes could cause diseases Before Pasteur’s time people thought a disease was a punishment for someone’s misdeeds. 1850s Pasteur discovered fermentation. Yeasts broke down sugars in grapes to release alcohol and CO2 If microbes could cause changes in grapes, they could cause changes in humans and animals Robert Koch proved the germ theory of disease

Fig. 1.6

Drew blood from the animals that had died of the disease. Isolated a rod-shaped bacterium (isolate #1) Grew bacterium in the lab and obtained a pure culture of the bacterium. Injected bacterium into healthy animals. They got sick and died. He isolated rod shaped bacterium from these animals (isolate #2)

Compared the 2 isolates and found that they were identical. Anthrax. Bacillus anthracis. The above steps are known as Koch’s postulates. They are used even today to determine the causative agent of a mysterious infectious disease.

Koch’s postulates The microorganism must be present in every case of the disease but absent from healthy individuals. The suspected microorganism must be isolated and grown in a pure culture. The same disease must result when the isolated microorganism is inoculated into a healthy host. The same microorganism must be isolated again from the diseased host.

The Development of Techniques for Studying Microbial Pathogens Koch’s work led to discovery or development of: agar petri dish nutrient broth and nutrient agar methods for isolating microorganisms

Other developments… Charles Chamberland (1851-1908) developed porcelain bacterial filters used by Ivanoski and Beijerinck to study tobacco mosaic disease determined that extracts from diseased plants had infectious agents present which were smaller than bacteria and passed through the filters Infectious agents were eventually shown to be viruses

Immunological Studies Edward Jenner (1798) used a vaccination procedure to protect individuals from smallpox Cowpox materials from cowpox lesions to protect people from snallpox.

The Development of Industrial Microbiology and Microbial Ecology Louis Pasteur demonstrated that alcohol fermentations and other fermentations were the result of microbial activity developed the process of pasteurization to preserve wine during storage

Additional Developments… Sergei Winogradsky (1856-1953) and Martinus Beijerinck (1851-1931) studied soil microorganisms and discovered numerous interesting metabolic processes (e.g., nitrogen fixation) pioneered the use of enrichment cultures and selective media

The Scope and Relevance of Microbiology importance of microorganisms first living organisms on planet live everywhere life is possible more numerous than any other kind of organisms global ecosystem depends on their activities influence human society in many ways

Microbiology has basic and applied aspects Basic aspects are concerned with individual groups of microbes, microbial physiology, genetics, molecular biology and taxonomy Applied aspects are concerned with practical problems – disease, water, food and industrial microbiology

Microbiology actually represents many fields of study Many specialties Examples medical microbiology is concerned with diseases of humans and animals immunology is concerned with how the immune system protects a host from pathogens

More fields… microbial ecology is concerned with the relationship of organisms with their environment microbial genetics and molecular biology are concerned with the understanding of how genetic information functions and regulates the development of cells and organisms

The Future of Microbiology: Challenges and opportunities for future microbiologists infectious disease new and improved industrial processes microbial diversity and microbial ecology less than 1% of earth’s microbial population has been cultured

Easier to grow Results can be obtained faster Easier to manipulate their environment and their DNA Most of the concepts and processes in biology are first discovered in microbes Gave foundation that helped scientists to discover the processes in other organisms including humans