Chapter 1: A Brief History of MicrobiologyThe Scope of Microbiology- Microbiology: a specialized area of biology that deals with the study of living things too small to be seen without magnification (microscope)- Microorganisms: a large, diverse group (different types) of microscopic organisms that exist as single cells or cell clusterso Commonly called germs, viruses, agents, but not all cause disease and many more are useful or essential for human life o Distinct from the cells of animals and plants, which are unable to live alone in nature and can exist only as parts of multicellular organismso Liver cells can’t survive on their own The Impact of Microbes on Earth (vitally important)- Microorganisms have had a profound influence on all aspects of the Earth andits residents- Microbes have extensively shaped the development of the Earth’s habitats and the evolution of other life formso When looking for life on other planets, scientists first look for signs of microorganisms- Bacterial-type (prokaryotic) organisms have been on Earth for ~3.5 billion yearso They were the only living inhabitants for ~2 billion years- Ubiquitous: can be found nearly anywhereo Live in places where other organisms cannot - Play central roles in processes that are essential to life Microbial Involvement in Energy and Nutrient Flow- Deeply involved in flow of energy and food through the Earth’s ecosystems- Photosynthesiso Anoxygenic o Oxygenic  Bacteria were responsible for changing the atmosphere of the Earth from one without oxygen to one with oxygen Photosynthetic microorganisms account for >50% of Earth’s photosynthesis, contributing the majority of the oxygen to the atmosphere As humans we are more concerned with oxygenic- Most of the air we breathe come from microorganisms- Decomposition and nutrient recyclingo Breakdown of dead matter and wastes into simple compounds that can be funneled back into the natural cycles of living thingso Breaks down leaves in the fall and grass when we cut it, primarily fungiHuman Use of Microorganisms- Humans have been using microorganisms for thousands of yearso Examples Baker’s and brewer’s yeast Cheese production Moldy bread on woundso Biotechnology: the human manipulation of microorganisms to make products in an industrial setting – cheese production- Genetic engineering: manipulation of the genetics of microbes, plants, and animals in order to create new products and GMOso Recombinant DNA technology: altering the DNA of one organism by transferring genetic material from another organisms to it Genes from microbes – insert into corn – can withstand certain things- Bioremediation: the introduction of microbes into the environment to restorestability or to clean up toxic pollutantso Large area of microbiologyInfectious Diseases and the Human Condition- Most microbes that associate with humans cause no harm and in fact provide many benefits- ~2000 microbes that cause disease (pathogens)o <1% of all microbes- More beneficial microbes- Infectious diseases still devastate human populations worldwide and are among the most common causes of death in much of human kindo Malaria: caused by a protozoan- Increasing number of emerging and reemerging diseases (SARS, AIDS, hepatitis C, viral encephalitis)o Some advances in eradication (vaccination) Polio, small pox, etc. o Great need for vaccinations – ex. malaria- Many diseases previously thought to be noninfectious probably do involve microbial infectiono Gastric ulcers, cancers, diabetes, schizophrenia, multiple sclerosis, OCD, female infertilityo Due to stress- Immuno-compromised patientso Non functioning immune system o Cancer, cervical cancer specifically - Increasing number of drug resistant stains o Antibiotic resistant bacteria Longer stays in the hospital to recover How Can Microbes Be Classified? (different types)- Bacteria and Archaea- Fungi- Protozoa- Algae- Other organisms of importanceo Parasitic worms (helminthes)o VirusesThe General Characteristics of Microorganisms PROKARYOTEEUKARYOTEBacteria and Archaea (Prokaryotes)- Prokaryotic o No membrane-bound nucleus - Lack various organelles bound with phospholipid membranes- More prokaryotes live on the body than eukaryotes inside- Bacteria have cell walls containing peptidoglycan (unique to bacteria)- Archaea have cell walls that are composed of polymers other than peptidoglycan- Most are much smaller than eukaryotes (10 folds smaller)- Live in almost every habitat containing sufficient moisture- Archaea are often found in extreme environments- Only a few bacteria and no known archaea are capable of colonizing humans and causing diseaseFungi- Eukaryotic o Have membrane-bound nucleus - Single cells or filamentous (multiple cell)- Obtain nutrients by breaking down organic mattero Ecologically importanto More harmful to plants - Possess cell walls o No peptidoglycan- Some are harmful to plants, animals, and humans, but others are useful- Moldso Typically multicellularo Have hyphaeo Reproduce by sexual and asexual spores- Yeastso Unicellular o Reproduce asexually by buddingo Some produce sexual sporesProtozoa- Single-celled eukaryotes that contain at least one nucleus- Similar to animals in nutrient needs and cellular structureo No cell wall- Live freely in water; some live in animal hosts (malaria)- Asexual (most) and sexual reproduction- Some have complex life cycles involving more than one host- Most are capable of locomotiono Pseudopodia: cell extensions that flow in direction of travelo Cilia: numerous, short, hair-like protrusions that beat rhythmically together to propel the cell through the environment (helps with movement and eating)o Flagella: extensions of a cell that are fewer, longer, and more whip like than cilia (propeller like)Algae- Unicellular or multicellular eukaryotes- Not harmful to humans- Need sunlight to grow- Can produce toxins that can in turn be harmful to humans- Photosynthetico Make their own food from carbon dioxide and water using energy from sunlighto Unicellular algae produce most of the world’s oxygen- Found near surface of fresh or salt water- Simple reproductive structures- Categorized on the basis of pigmentation and composition of cell wall - Algae are critically important to global ecology, but they gave negligible medical importance- DiatomsOther Organisms of Importance to Microbiologists- Parasitic wormso Eukaryotico Adult forms are macroscopico Microscopic eggs and immature