1 1 What is a Microbe Chapter 1 Microbial Life Microbe living organism that requires a microscope to be seen mm 0 2um in size single cell with cell membrane wall the capacity to reproduce Viruses are 10x smaller 100nm Both prokaryotes bacteria archaea and eukaryotes Include members of all 3 kingdoms Bacteria Archaea Eukarya protists etc Has its own genome of several million bp s 1kD bp s gene Exceptions supersized 1mm microbial cells marine sulfur killer algae microbial communities mushrooms kelps biofilms viruses considered a microbe but not a functioning cell Only 0 1 of the microbes in our biosphere can be cultured in laboratories Microbial disease is the 1 cause of human mortality 1800s golden age for microbiology human tissue could be distinguished from microbial cells Genome total genetic info in chromosomal DNA of an organism First genomes to be sequenced were of viruses Fred Sanger developed first method of DNA sequencing w large genome sequences o 1980 Nobel Prize o Completed first genome sequence of a bacteriophage 5000 bp 10 genes o Previously separate genome into multiple cosmids and sequence individually Metagenome sequences taken directly from the environment Craig Venter Celera Genomics TIGR The Craig Venter Institute o 1995 first genome sequence of a cellular microbe Haemophilus influenzae o Also sequenced Bacillus anthracis Colwellia psychrerythraea o Invented the shotgun sequencing technique most popular 1 2 Microbes Shape Human History Yeast bacteria food beverages cheese bread wine Rock eating bacteria lithotrophs enabled mining of metals by leaching cooper Lithotrophic oxidation of minerals for energy generates strong acid breaking down the ore About 20 of world s copper plus some uranium and zinc is produced by bacterial leaching Disease Microscopes 14th century bubonic plague Yersinia pestis wiped out 1 3 of Europe s population 19th century tuberculosis Mycobacterium tuberculosis Today Ebola AIDS HIV Florence Nightingale British nurse and statistician who recognized the significance of disease in warfare more soldiers have died from infections than from wounds in battle First built in the 1600s time of Isaac Newton Robert Boyle conversion of matter Robert Hooke built first compound microscope to observe mold coined the term cell Antoine van Leeuwen invented a better microscope to observe first single cell microbe o Found that heat killed the microbes in his teeth o Believed to have died of a disease contracted from sheep whose bacteria he observed Spontaneous generation theory that living creatures could arise without parents Francesco Redi showed maggots in decaying meat were offspring of flies argued against spontaneous generation Lazzaro Spallanzani worked to disprove spontaneous generation o Showed sealed flask of meat broth sterilized by boiling failed to grow microbes o Demonstrated cell fission by watching a single microbe divide into two Louis Pasteur disproved spontaneous generation o Discovered the microbial basis of fermentation the process of microbes gaining energy by converting sugars to alcohol via living yeast o Devised swan neck flasks showed after boiling the contents remained free of microbial growth despite access to air o Developed first vaccines based on attenuated weakened strains o Discovered fundamental chemical property of chirality symmetry in molecules John Tyndall showed repeated cycles of heat were necessary to eliminate spores formed by certain kinds of bacteria Autoclave steam pressure device standard method for sterilization effectively kills endospores 1 3 Medical Microbiology Germ Theory of Disease many diseases are caused by microbes germs Robert Koch one scientist who established this theory o Researched anthrax and TB o Koch s Postulates criteria for establishing a causative link between an infectious agent and a disease 1 Microbe is always present in diseased host absent in healthy 2 Microbe is grown in pure culture no other microbes present 3 Introduce pure microbe into healthy host individual becomes sick 4 Same microbe re isolated from now sick individual Differences today many microbes are un culturable only grow in vivo microbe in healthy patient may not get sick immediately time of onset could be years Richard J Petri invented the covered petri dish Angelina Hesse used agar which remained solid for culturing Immunization stimulation of an immune response by deliberate inoculation with an attenuated pathogen First protection from deadly disease smallpox Lady Mary Montagu introduced smallpox inoculation to Europe 1717 o Children were deliberately inoculated with a mild case of smallpox via material from smallpox pustules which contained naturally attenuated virus Edward Jenner deliberately infected patients with matter from cowpox lesions 1749 1823 cowpox inoculation vaccination from similar smallpox established practice of vaccination o Cowpox was the basis of the modern smallpox disease Louis Pasteur o Studied fowl cholera transmissible disease of chickens o Found that a weakened attenuated microbe with less potency to cause disease could o First case of immunization through vaccination attenuation through heat treatment or still confer immunity aging o Most famous vaccination rabies complex series of heat treatments and inoculations o This vaccination lead to the development of the Pasteur Institute who discovered HIV Antiseptics Antibiotics Ignaz Semmelweis ordered doctors to wash their hands with chlorine antiseptic agent to prevent the spread of infection 1847 mortality rates fell Joseph Lister developed carbolic acid to treat wounds and clean surgical instruments 20th century aseptic surgery was developed microbe free environments Antiseptic chemicals killed microbes patients antibiotics would kill only microbes Alexander Fleming o While culturing Staphylococcus found one plate contaminated with the mold Penicillium notatum which was surrounded by a clear region free of Staph o Discovered Penicillium notatum mold generated a substance that killed bacteria aka penicillin 1929 first antibiotic o Microbes produce antibiotic compounds with highly selective effects Howard Florey Ernst Chain purified penicillin 1941 first commercial antibiotic to save lives o Penicillin inhibits formation of the bacterial cell wall Mode of action for antibodies studied until 1990s interferes with peptidoglycan of cell wall Antibiotic resistance ex Mycobacterium tuberculosis Discovery of Viruses Dmitri Ivanovsky studied tobacco