M Ashcraft The origin of Microorganisms Anthony van Leeuwenhoek s Robert Hooke first to observe a microorganism animalcules were discovered in 1674 Using ground glass observed bread mold De bunked by Francesco Redi Italian at the end of the 17th century Worm and meat experiment Covered one meat with cheese cloth and found no maggots formed Disproved spontaneous generation the theory that suggested organisms can arise from non living material Despite his Redi s work the microorganism s generation was difficult to refute because various experiments yielded conflicting results John Needham 1749 showed that various boiled broths gave rise to mirco organisms Because brief boiling was thought to kill all microbes this supported s generation Spallanzani 1776 boiled the infusions longer and with a sealed tube killing all the microbes and proving that s generation was impossible When the neck cracked the broth would become cloudy Others argued that boiling destroyed the vital force necessary for spontaneous generation Louis Pasteur 1861 French chemist who refuted s generation debate Discovered air is filled with mirco organisms Filtered air through a cotton plug trapping organisms to be examined under a microscope Looked identical to those in the infusions When dropped the cotton plug into the broth saw that the microbes multiplied 2 Proved that sterile infusions would remain sterile unless tainted Organisms from the air would settle in the bend of the swan neck flask and not escape and would never reach the sterile solution John Tyndall finally explained the differences between Pasteur s mixed results Different infusions require different lengths of boiling time Found that there was heat resistant microbes by studying hay Found that there were 2 types of microbes o o Those killed by boiling Those that are heat resistant Heat resistant endospores Bacillus Clostridium o Also discovered by Cohn and Koch o Mostly from soil Proved that every part of an experiment must be replicated in order to produce the same result Mircobiology a human perspective Features of a Mircobial World Microbes including living and non living agents of the microscopic world Microscopic Extreme biodiversity Account for most of the world s biodiversity Diverse among each other Most abundant largest biomass Vital Roles Bacteria convert nitrogen into usable forms air usuable for plants Aquatic organisms replenish oxygen Degrade cellulose sewage and waste water Longest living form of life on earth Applications of Microbiology Food Production Cheese bread yogurt beer Bioremedition Degrade environmental pollutants like TNT PCD DDT M Ashcraft Medical Micro Useful Products Ethanol antibiotics cellulose Past Triumphs Killed more than war Small pox plague Present and Future Challenges Many emerging diseases Lyme etc New opportunities for spreading in rapidly moving world Changing lifestyles bring more chance of disease Resurgence of Old Diseases Microorganisms as Model Organisms Travel is main concern Vaccination is becoming more lax as the disease is dormant in pop Pop is inc in number of elderly people 3 Distinct Domains Bacteria Look identical to Achaea Prokaryotic DNA is in nucleiod Cylindrical rod spherical spiral o o o o Rigid cell walls contain chemical peptidoglycan o Binary fission divides into 2 indentical cells o Flagella Archaea Prokaryotic Eucarya o o o o 1000x smaller than eukaryotic Same as Bacteria in shape comp flagella binary fission but no peptidoglycan o Grow in extreme environments Eukaryotic Mitochondria Golgi body endo reticulum carried out by Organelles enveloped in membranes inside the cell DNA inside nucleus membrane in prokaryotics Includes single or multiple celled mirco or macroscopic large microorganisms like mushrooms energy from sunlight rigid cell wall generally aquatic Algae move by means of flagella fungi mostly terrestrial protozoa microscopic Aquatic and terrestrial environments No rigid cell wall Single celled Organic material organic material single or multi celled micro or macroscopic helminth round and tapeworms unlike fungi and algae rigid cell wall organic compounds as food Viruses Viroids Prions M Ashcraft Nonliving acellular agents Virus Viroids Prions A piece of nucleic matter DNA or RNA surrounded by a protein coat Only multiply inside of the host cell using the host s process of reproduction Obligate intracellular parasites Can make the host cell produce toxin Phage therapy treating infection with vrisus that infect bacteria Bacteriophage viruses that infect bacteria Single short piece of RNA without a protein coat Mostly plant pathogens Protein without any nucleic acid and a form of abnormal protein Cause neurological disease Can be denatured by pH heat When denatured stick together and aggregate