History of Microbiology

1. Before the discovery of microbes, reports were there that some organisms are associated with diseases. Lucretius (about 98-55 BC) and physician Giralomo Fracastoro (1478-1553) suggested that diseases are caused by invisible living creatures

2. Francesco Stelluti (Italian) was first to use microscopic observation between 1625 to 1630 of bees and weevils by the microscope provided by Gallileo

3. Microbiology the science of microbes got late start when other branches were established because the tool (microscope) to observe the very small group of organism was not there. The existence of microbes was reported in mid1600

4. Credit for this this momentous development goes to two great scientists Robert Hooke and Anton Von LeeuenHoek

Robert Hooke (1635-1703)Curator of experiments of Royal Society of London He spent much of his time in examining various materials under his own compound microscope and published his reports in book entitled MicrographiaBook contained detailed drawing of insects, their larve, eggs, feathers, hairs, rocks and cork.He was first to report Fungi“Long Cylindrical transparent stalks not straight but a little blended with weight of a round white knobs which grew on top of each of them”He suggested these knobs as common spore bearing cups of common white mushroom. He suggested the compartmentalization of structures in living systems, now known as Cells

Anton Van LeeuwenhoekCredit for discovery of microbes goes to Leeuwenhoek Born in Delft in 1632and at age of 16 sent to Amsterdam to apprentice in a draper shop to learn the technique and appointed as cashier before returning to DelftAlthough not attended any University but learned Mathematics became a successful businessman, a surveyor and official wine gauger for the town of Delft. Taking the last responsibility he assayed all the wines entering the town and have responsibilities to calibrate the vessels in which they were transported. During this time the institutions were mostly devoted to theology, law and philosophyHis main hobby was to construct Microscope and spent his maximum life in making Microscopes and he was first to observe microbes. His friend Renier de Graaf communicated several works to Royal Society in England

Henary Oldenberg was the editor & was of opinion that scientific informations should not have nationalistic restrictions. So, Leeuenhoek was encouraged to communicate his findings First report in Philosophical transaction dealt with mouth parts, molds, eyes of bees, louse. Due to Oldenbergs contact and translation of his work generated interest in scientific world. He continuously send letters to Royal Society and unanimously elected as fellow of Royal Society. Over 200 of his letters have been preserved in the Museum of Royal Society.In 18th of his letter October 9th , 1676 first description of unicellular organisms (Protozoa) and first report of small microbe like bacteria was covered. He studied water from fresh water lake, river, well, rain and sea. He termed these as “animalcules” Most important was from human mouth, he wrote in 1683.

He described rod shaped bacteria, spherical, cork screw shaped bacterial forms.His observation remained unconfirmed for many years because no one was able to make the microscopic observation of quality needed to observe bacteria. His microscope was send to Royal Society in London, no body followed in Leeuenhoeks foot steps and the branch of Microbiology remained dormant for many years after his death

Microbiology study of microbial forms is multifaceted discipline concerned with infectious diseases, agricultural practices, sanitation and industrial production of enzymes, chemicalsMicrobes are unique models to study nutrition, metabolism and genetics and used as instruments in development of BiotechnologyMicrobes have marked effect on course of human population, history, strength of armies, out comes of battlesDecline of Rome under emperor Justinian (AD 565) was hastened by the epidemic of bubonic plague and Smallpox. The people of Rome were decimated & demoralized by the massive epidemic and as a result were powerless against Barbarian hordes which destroyed empire

Important diseases were Typhus, Plague, Small pox, syphilis, cholera caused suffering and great loss of human lifePopulation of Europe, N. America and Middle East was about 100 millions when Plague (black death) struck in 1936, Epidemic came down through “silk road” to China, bringing Death to Asia, Mean time spread to Europe and within a short period caused loss of 25 million people in short time.This caused population in check in 16 and 17th century. Last great epidemic occurred in 1720 & 1722 in France

Appeared in India in 1892 & killed 6 million people in India aloneDuring this time Napoleon began his retreat from Moscow in 1312, most of his army became victim of typhus, pneumonia, dysentery and other illness. Diseases cold & deprivation all played leading roles in his departure.In 1813 again recruited new army of 5,00,000 young warriors, huge population with unsanitary condt. Rendered them susceptible to infectious diseases.When faced allies at Leipzig, battle and diseases reduced his army to approximately (5,00,000 to 1,76,000) causality of earlier battle 1,05,000 but about 2,20,000 people were incapacitated by illness. So, microbes were responsible for his defeat.

Status Prior to 1650From dawn of civilization until middle of 19th century – success in combating diseases, fight against destructive power, harnessing fermenting ability Process of trial & errorThoughts were influenced by Philosophers & supported by Theory of Spontaneous generation supporting “Origin of living organisms from inert organic material”Aristotle (384-322 BC) & others wrote abundantly that Frogs originated from damp earth, flies on decaying meat, mice on grainsGiralomo Fracastoro suggested contagious is involved in disease processScholars of

• 16th and 17th Century seeking logical explanation to phenomenon in nature. None of the explanations were obtained for natural processes, when scientists especially chemists clung to theory of chemical instabilities & spontaneous generation.

• Van Helmont (1580- 1644) produced a recipe for producing mice from soiled clothing and little grain

Microbiology from 1650-1850

• 18th century age of enlighten during this time period people questioned traditional doctrine. Biological sciences get benefitted by the discovery of microscope and realization that living system is composed of individual units called as cells.

• Fabrication of microscope attributed to Dutch Zacharium Jansssen and microscope was first time used for biological material by Marcello Malpighii and he can be considered as Father of Microscopic Biology, contributed in discovery of capillaries and understanding of embryonic processes

From Leeuenhoek to Pasteur

• Many experiments were conducted between (1725-1850)• Many of the regarding the Theory of Spontaneous Generation• Francisco Redi 1627-1697 Italian physician published a book

in 1688 attacking theory of Spontaneous Generation• He is most well known for his series of experiments, published

in 1668 as Esperienze Toronto alla Generazione degl'Insetti (Experiments on the Generation of Insects), which is regarded as one of the first steps in refuting "spontaneous generation" - a theory also known as Aristotelian abiogenesis. At the time, prevailing wisdom was that maggots aformed naturally from rotting meat.

• Spontaneous Generation-The idea that organisms originate directly from nonliving matter. "life from nonlife"

• abiogenisis - (a-not bio-life genesis-origin)

• Redi took six jars, which he divided in two groups of three: • In one experiment, in the first jar of each group, he put an unknown

object; in the second, a dead fish; in the last, a raw chunk of veal. Redi took the first group of three, and covered the tops with fine gauze so that only air could get into it. He left the other group of jars open. After several days, he saw maggots appear on the objects in the open jars, on which flies had been able to land, but not in the gauze-covered jars.In the second Redi's experiment, meat was kept in three jars. One of the jars was uncovered, and two of the jars were covered, one with cork and the other one with gauze. Flies could only enter the jar with the lid off of it, and in this, maggots appeared. In the jar that were covered with gauze, maggots stayed on the gauze and did not live.

• He continued his experiments by capturing the maggots and waiting for them to metamorphose, which they did, becoming flies. Also, when dead flies or maggots were put in sealed jars with dead animals or veal, no maggots appeared, but when the same thing was done with living flies, maggots did.

Lazzaro Spallanzani - One of the first to disprove spontaneous generation. An Italian scientist who proved microorganisms could be killed by boiling. (Italian 1767)

• 1768 Needham's experiment but removed all the air from the flask. No growth occurred

• What causes microbes to form in decaying broth?• Hypothesis: Microbes come from the air. Boiling will

kill microorganisms.• Spallanzani put broth into four flasks • Flask 1 was left open• Flask 2 was sealed• Flask 3 was boiled and then left open• Flask 4 was boiled and then sealed

•Flask-2•Sealed •Turned cloudy•Microbes were found•Flask-3•Boiled and left open•Turned cloudy•Microbes were found•Flask-4•Boiled and sealed•Did not turn cloudy•Microbes not found• Spallanzani's Experiment Results• What did Spallanzani's experiment show?• Was his hypothesis correct or incorrect?

• John Needham added chicken broth to a flask and boiled it. He then let it cool and waited. Microbes grew, and he proposed it as an example of spontaneous generation.

• In 1768,Lazzaro Spallanzani repeated Needham's experiment but removed all the air from the flask. No growth occurred.[5]

• In 1854, Heinrich Schröder (1810–1885) and Theodor von Dusch, and in 1859, Schröder alone, repeated the Helmholtz filtration experiment[6]

and showed that living particles can be removed from air by filtering it through cotton-wool.

Franz Schulze (1815-1873)• German chemist took flask filled with vegetable infusion

closed with a cork to which 2 bend glass tubes were fitted infusion was heated on sand bath & absorption bulb was attached to tubes (one contained concentrated Sulfuric acid and other a solution of potassium hydrate, everyday he drew air through potash bulb & passed through the acid bulb & flasks remained sterile for months A control flask without acid sterilization of incoming air had visible mold growth after few days. Sterilized flask when exposed to air growth followed with in few days

• Conclusion Infusion could be sterilized & microbes could be introduced through air

Research on Fermentation• In many reports, the beginning of research on

fermentation and on the role of yeast is given as 1810, when J. L. Gay-Lussac (1778–1850), on the basis of detailed analyses, specified ethanol and CO2 as the principal products of the decomposition of sugar

• The true beginnings of research on fermentation date to around 1837, when three investigators independently described many of the principal features of yeast: Cagniard-Latour (1837) in France, and Schwann (1837) andKützing (1837) in Germany. Microscopic studies were the key to their scientific conclusions.

• Schwann observed beer Yeast consist of granules arranged in rows & resembling fungi. He believed them as plants. Gave the term Zuckerpilz (sugar fungus) from which the term Saccharomyces was derived, N was essential for this process. Another independent observation on fermentation was by Friedrich Kuitzing suggested this process was caused by living organisms. He also suggested different types of fermentations are caused by different microbes.

Classification• Linnaeus (1707-1775) was first to give classification system

in his book Systema Naturale (1743) Gave Binomial Nomenclature, animalcules as infusoria Bacteria was placed in the genus “Choas” emphasis was given on few characteristics

• Adanson (1730) proposed Adansonian system of classification, he gave equal weight to all characters

• Otto F Muller (1730-1784) animalcula et Marina published posthumously (1786) 379 sp of bacteria He first time used the term Vibrio & Monas

Medical Microbiology• Enrico Acerbi (Italian in 1822) postulated that parasites

exists & capable to enter the body & their multiplication caused Typhus fever

• Agostino Bassi (1835) advanced the theory on observation on diseases of silk worm. Diseases caused death of worms after death worms were covered with hard, white limy substance. This was supposed to arise independently from unknown factor. He found aseptic transfer of subcutaneous material from sick silkworm to healthy worm resulted in disease. Reported that disease was caused by a fungus Botrytis bassiana

• Developed the concept that Contagion in different diseases like Cholera, Plague, gangrene resulted from living parasites

Edward Jenner (1749-1823)• Published studies on the immunization of human against

Small pox. He observed that individuals routinely exposed to cows often develops pustules on their hands & arms similar to pustules of small pox. Infection of cowpox was not fetal and cowpox infected ones were resistant to small pox

• Jenner inoculated an 8 year old boy with material from infected cowpox pustule on the hand of a milkmaid pustules were developed at site of infection but quickly recovered A challenge dose from active case of smallpox was given and any symptom was not observed

• This was the first report of immunization

Microbiology after 1850 : Beginning of Modern Microbiology

• Golden Age of Microbiology• Later part of century no. of gifted scientists working

independently established areas now encompassed by the term Microbiology

• During this period foundation of Immunology, medical Microbiology, protozoology, systematics, fermentation, mycology were set apart

• Up to 1860 doctrine of spontaneous generation was accepted because chemists were infallible

• Louis Pasteur Brought revolution in the field of Microbiology

Louis Pasteur (1822-1895)• Chemist and genius scientist had unique ability to convince

and communicate to scientists and lay persons • Disproved the theory of spontaneous generation • Established immunology added a science• Developed the concept of Fermentation• Discovered Anaerobiosis• Many microbiological techniquesContributed in every branch of MicrobiologyPasteur SchoolEntered the controversy of Spontaneous GenerationFermentations were caused by organic living beings which

reproduce and by vital activities generate observed chemical changes. He suggested that germs are present in the air were responsible for fermentation and are widely distributed in nature. These germs are now a days termed as bacteria and fungi

• Louis Pasteur- Notable Contributions• 1857 – Lactic acid fermentation is due to a microorganism• 1860 – Yeasts are involved in alcoholic fermentation• 1861 – Disproved the theory of spontaneous generation• 1861 – Introduction of the terms aerobic and anaerobic for yeasts. Production of more

alcohol in the absence of oxygen during sugar fermentation- The Pasteur Effect• 1862 – Proposed germ theory of disease• 1867 – Pasteur devised the process of destroying bacteria known as pasteurization.• 1881 – Development of anthrax vaccine. Resolved Pebrine problem of silkworms.• 1885 – Development of a special vaccine for rabies (the Pasteur treatment)• Louis Pasteur, a French microbiologist, was born on December 27, 1822 in Dole, France.

He studied at the French school, the Ecole Normale Superieure. • In 1848, he achieved distinction in organic chemistry for his discovery that tartaric acid, a

four carbon organic compound forms two different types of crystals. Using a microscope, Pasteur successfully separated the crystals and developed a skill that would aid his later studies of microorganisms.

• In 1854, at the young age of 32, he was appointed Professor of Chemistry at the University of Lille in northern France. He died in 1895, at the age of 73.

• He designed aspirator filter system (aware that spun cotton wool acts as effective filter for air borne microbe). He drew air in huge amounts through spun cotton wool & dissolved this in mixture of alcohol & ether. Microscopic examination revealed large no. of small oval, round bodies indistinguishable from germs previously described. Pasteur noted that the no. of these organisms varied with temp., moisture and movement of air.

• T. Schwann 1837 demonstrated that yeasts were responsible for formation of alcohol in wine & beer fermentation (before Justin Leibig gave chemical theory of fermentation & suggested that fermentation was result of normal chemical decomposition of organic matter

• He was attracted and analyzed many fermentations and suggested yeast was presented in all cases and responsible for fermentations

• He suggested that when lactic or butyric acid was produced bacteria was also present in addition to Yeast. Even when wine turned bad Bacilli was present in addition to Yeast. He suggested that sugar of ferment served as food for microorganism

• He professed that each ferment was caused by a specific organism which grows only when special requirement for its growth is available. He made a defined medium containing sugar and salts which was converted to alcohol and cell material. Nitrogen was available to cells as Ammonium salts

• Observation served as basis for microbial physiologyAnaerobic & aerobic growthAir requiring organisms are aerobes and scientists of middle of 19 th

century were of opinion microbes require oxygen He observed that organisms involved in butyric acid fermentation exists in anaerobic environment & observed their motility under microscope. This motility ceases when cultures were aerated. Finally he coined the term anaerobiosis

Disproved Spontaneous Generation• Pasteur’s brilliance combined with his knowledge of

fermentation & he started working on fermentation According to him entry of microbes to suitable media is responsible for fermentation and prevented to enter fermentation was not possible. For that he heated the flaks and after that placed guncotton on top of flasks. Flasks remains uncontaminated until the cotton was removed.

• He further invented a swan neck flask, thus allowed unencumbered entrance of air, where all of the dust particle and contaminants settled in the bend of neck

• Heated Flasks of this type remained clear and free of fermentation until he broke off the neck. Flasks with broken neck turned cloudy within few days. He explained that the organisms capable of fermentation exists in air and when precautions were taken to prevent the entry of to broth fermentation did not occurred. He suggested different samples contained different microbes

• He opened the flasks to different places- mountains, lakes, attics, cellars and resealed the flasks . He showed that different samples have varied population of microbes from place to place

• He assured boiling of broth for 1 hr killed all living microbes (eventually incorrect). This lead the proponents to attack Pasteur. In fact some microbe not killed when broth was heated for 1 hr (this is why his experiment succeeded with Yeast extract and not with other broths

Ferdinand Cohn 1877 (1828-1898) published a paper on rod shaped bacteria producing resting spores (endospore) resistant to heat and can easily be identified under microscope. Spore appeared as retractile objects under microscope His interest on heat resistant bacteria emanated from emerging canning industries which sought ways to prevent purification of foods.

Cohn

• Cohn described the entire life cycle of Bacillus (vegetative cell → endospore → vegetative cell). He

• is credited with the use of cotton plugs for closing flasks and tubes to prevent the contamination of

• sterile culture media. In 1866, Cohn studied the filamentous sulphur-oxidizing bacterium Beggiatoa

• mirabilis and was the first to identify the small granules present in the cell that are of sulphur,

• produced from the oxidation of H2S.

• He found alkaline Hay infusion- difficult solution to sterilize- contaminated with Bacillus subtilis – where spores are vheat resistant. When transferred to fresh Hay infusion – spores formed actively growing and dividing cells

• Solution to this problem presented by John Tyndall (1820-1893) when he presented paper on Royal Society of London 1877. He recognized like Cohn infusion contained heat resistant spores and spores germinate to vegetative cells following brief exposure to heat & subsequent boiling killed the veg. cells From this observation he developed technique of alternating sequence of heat & growth this would kill the bacteria if present. This technique of sterilization was referred as tyndallization.

• The experiment of Pasteur & Tyndall demonstrated that microbes do not arose independently.

• 1865 Napoleon III asked Pasteur to investigate the cause of formation of bad wine & he suggested that this was caused by specific organism & it was different from the agent of good wine. He suggested that the grape juices be heated or pasteurized to destroy resident population and resultant sol. If inoculated with a proven producer produce good wine

• Working on butyric acid fermentation He studied Anthrax in farm animals & demonstrated immunization is possible. He also suggested that infection of Rabies settle in brain &nervous system of animals and immunization is possible. He outlined method for developing vaccine which could encounter harmful effect of Rabies. In 1885 he reported a dog was protected from infection by inoculation with an emulsion prepared from dried spinal cord of Rabbit that had succumbed to disease and developed vaccine

Robert Koch• Anthrax a fatal disease of domestic animals caused economic

loss to farmers in late 19th century. Disease appeared in the herd of Sheep or cattle without any apparent cause or source

• Before his work indications were there that Anthrax was caused by a bacterium. Rod shaped bacterium appeared in the blood of infected animal. One microbiologist transferred anthrax by inoculating animals with dried or fresh blood containing bacteria. But unable to prove that bacteria caused the disease

• He quickly ruled out the idea of using sheep as experimental organism because too expensive he used mice as model because susceptible to Anthrax

• He took blood from infected animal and injected to healthy mice. He repeated it several times and found each time mice died if Anthrax. He found swollen spleen and presence of Bacilli in both liver & spleen

• He started to culture Bacillus in broths without success Finally he raised aqueous humor (liquid from eye ball) of cow. He placed a drop of aqueous humor on thin glass cover slip & inoculated it with a piece of infected spleen. He inverted this cover slipover a depression slide to make hanging drop

• He observed the growth of Bacilli as vegetative cells as before many of them formed refractive spores. He inoculated a fresh drop of humor and observed their germination into vegetative cells. Once he was able to grow the infectious agent outside the host Koch was aware how to proceed. He finally discovered Koch’s postulates earlier given by Henle

• He used inoculation components as spores more spores he used more quickly the mice died & once again Bacilli was recovered from blood & spleen. Experiments proved that microbes can cause infectious diseases

• Finally in 1884 Koch summarized his methods of proving that a microbe is causative argent of infectious diseases, a method known as Koch’s postulates

Koch’s postulates1. Microbes must be demonstrable in all cases of diseases2. Microbes can be isolated from diseased animal & can be grown

to pure culture3. Microbes from this pure culture must cause the same disease

when inoculated to a healthy host4. Experimentally infected animal must contain same microbeBy this time R Koch was recognized as leader of German school of

Microbiology in Berlin.Technical advances in obtaining pure culture. He observed

unrefrigerated boiled potato developed various spots of varying colours. Microscopic observations of these spots revealed presence of bacteria – one spot was rods, another spherical (coccus), one Yeast, separation of contaminants

From surface permitted growth of pure culture (single cell into colony of many progeny cells). From these trials he developed techniques which enabled microbe hunters to grow pure culture of microbes Koch used gelatin as solidifying agent to create a firm surface on which to streak microbes. Gelatin was effective at room temp. but liquefied at temp. above 30oCDr Walter Hess & his wife Fenny Hess introduced Agar as solidifying agent (used to harden Jelly). Ideal solidifying agent because after solidifying at 44oC it remains solid even at 70oCMany of the bacterial agents causing infectious diseases were discovered between 1877-1898. Pure culture technique led to a major break through in this medical era. He also suggested a colony arose from a single cell & developed streaking method using using platinum loop, enable him to isolate pure culture. RJ Petri 1887 an assistant of Koch developed Petri dishes, named after discoverer and still to day used for culture. Design remain unchanged except glass has been replaced by plastic

Elie MetchnikoffElie Metchnikoff, one of the associates of Louis Pasteur, was a Russian zoologist who lived in Paris and did his work at the Institute Pasteur, France. He was born in Kharkor priovince of Ukraine (USSR) in 1845. By the 1860s he had completed his formal studies in Embryology from various Universities of Kharkor, Russia, Germany and Italy. Metchnikoff coined the term “phagocytosis” which literally means” the eating of cells”. In 1884, he published account of phagocytosis, a defensive process in which the body’s white blood cells (WBCs) engulf and destroy microorganisms. Thus, he formulated the basic theory on which the science of immunology is founded: that the body is protected from infection by leukocytes that engulf bacteria and other invading organism (cellular immunity). He became an administrator to the Institute Pasteur in 1888 and eventually became its director. He was awarded the Nobel Prize in 1908. Metchnikoff’s notable contribution was on the Bacillus bulgaricus therapy and his underlying concept of health. Metchnikoff belived that streptococci and lactobacilli in yogurt assume residence in the intestine and replace organisms that contribute to aging. Despite eating large quantities of yogurt, Metchnikoff died an early death, in 1916, at age seventy-one.

List of Diseases & InventorsDisease Causal organism Inventor

Anthrax Bacillus anthracis R KochGonorrhea Neisseria gonorrhoeae Albert NeisserPyrrogenic Infection Staphylococcus aureus Alexender ogstonTuberculosis Mycobacterium tuberculosis R KochErysipelas Streptococcus pyrogenes FiedrichFehleisenDiptheria Corynebacterium diptherae Theodor KlebsTetanus Clostridium tetani Arthur NicolaierCholera Vibrio cholerae R KochTyphoid Salmonella typhae Georg GaffkyBrucellosis Brucella melitensis David BruceGastroenteritis Salmonella enteritidis August gaetnerGas gangrene Clostridium perfringins Willium WelchBubonic plague Yersinia pestis Alexender YersinBotulism Clostridium botulinium Emile van ermengem

Dysentry Shigella dysenteriae Kiyoshi Shiga

Paul Ehrlich

• Another coworker of Koch lab contribution in immunology and chemotherapy

• Suggested staining technique of bacteria in tissues where bacterial cells absorb higher amount of dyes in comparison to surrounding tissues

• He suggested that a toxic dye might destroy bacteria without significant damage to host, reported that organic arsenicals might be synthesized which could be harmless to animals but toxic to invading parasites. Arsenicals (organic derivatives of arsenic- a toxic element synthesized & used on Trypanosomal infections on Rats. 606 th compound he synthesized was found to be effective against Syphlis Spirocheate and gave the term Magic Bullet

• In late 20 years Koch & his coworkers confirmed that microbes were causative agent for a no. for a number oif human & animal diseases

• John Snow, a British physician, traced the source of cholera to the municipal water supply of London during an 1854 outbreak. He reasoned that by avoiding the contaminated water source,people could avoid the disease.

• Snow’s recommendations were adopted and the spread of disease was halted. Both Semmelweis and Snow drew attention to the fact that a poison or unseen object in the environment was responsible for the disease, but the proof was still lacking.

• Joseph Lister in 1867, developed a system of antiseptic surgery designed to prevent microorganisms from entering wounds.

Joseph Lister

• Joseph Lister was born in 1827. He developed a system of antiseptic surgery designed to prevent microorganisms from entering wounds in 1867.

• In 1878, Lister studied the lactic acid fermentation of milk and demonstrated the specific cause of milk souring. He also developed a method for isolating a pure culture of a bacterium, named as Bacterium lactis. Because of his notable contribution-first introduction of principles of sterile surgery in medical practice, which was so far reaching in its effects—Lister will always be known as the Father of antiseptic surgery.

• He died at the age of 85 in the year 1912.

• Chemical antiseptic originated with Joseph Lister 1827-1912 , English physician who employed carbolic acid for antisepsis during surgery. Koch extended his work & deviced a method for comparing efficiency of chemical antiseptics. He dried cultures of bacteria generally anthrax spores. On a small piece of silk thread which was then immersed in antiseptic solution. At intervals thread was removed from antiseptic solution washed with sterile water and placed in growth medium to determine whether organism was still viable. Koch found that carbolic acid was weak in its disinfecting property and among all the chemicals he tested perchloride of mercury was most effective. It destroyed bacterial spores at high dilution & in the shortest period of time.

• Ferdinand Cohn in 1872 suggested that microbes are involved in cycling all of all matters & this activity of microbes in the biosphere allowed the reutilization of cellular constituents

Martinus Beijerinck (1851-1931)

• A great Botanist as first to report the role of microbes in cycling of matter.

• He introduced the concept of “enrichment cultures” ( a method for isolation of microbes under any selected condition such as salinity, osmolarity, temp, pH etc and isolated various forms from natural environment. enrichment medium is prepared with a defined chemical composition & inoculated with soil or water rich in microbes.

• He discovered free living nitrogen fixing bacteria by enrichment media devoid of nitrogen. Aerobic forms he named as Azotobacterium. Studied Rhizobium Symbiotic nitrogen fixer

• He described major group of bacteria. The luminous bacterium Photobacterium, sulphate reducers (Desulfovibrio)

• Methane generating bacteria, Thiobacillus denitrificans (denitrifying bacteria) He proposed the genus Lactobacillus

• Recognized existence of soluble living organisms he called as “Contagium Vivum Fluidum” accepted as initial description of Virus (TMV). He opened the concept of physiology, ecology and Environmental Microbiology

Sergei Winogradsky (1856-1953)

• Born in Russia & witnessed the origin of Microbiology and survived to see the age of even antibiotics Both Winogradsky & Beijerinck spent time in the lab of great mycologist Sir Anton de Bary (1831-1888). From his studied on Baggiatoa he concluded that organism could utilize inorganic H2S as source of energy & atmospheric CO2 as C source for synthesis of cellular material. Named these organisms as orgoxydants & opened the concept of Autotrophy

• After the death of de Bary he went to Zurich where he isolated and clarified the role of nitrifying autotrophic bacteria

• He also suggested that Green & Purple Sulphur Bacteria could oxidise H2Sto sulphate but not certain whether this process was photosynthesis.

• He isolated N2 fixing anaerobic Clostridium pasteurianum

• At this time noted scientist & Noble Laureate Elie Metchnikoff (1845-1916) carried a personal letter from Pasteur to Zurich inviting Winogradsky to work at Pasteur Institute

• Metchnikoff was discoverer of Phagocytosis & cellular immunity

• He refuged the proposal & thought to return to Russia, thus ending the first half of his illustrious scientific carrier

• He visited Paris in 1892 to represent Russia in 70th birthday of Pasteur.

• After the revolution of Russia he migrated to Pasteur institute & spent his life

• Specifdic role of blood in immune response better understood throuh the work of Emil von Behring & Shibasaburo Kitasato –he discovered that Tetanus is caused by a bacterial toxin produced by Clostridium tetani

• He with von Behring demonstrated that rabbits immunized with inactivated tetanus toxin (toxoid) rendered immune to tetanus. Blood taken with immunized one mixed with tetanus toxin destroyed. More over when the immune serum (serum blood minus cells & clotting factor ) was injected to mice protected from tetanus. First demonstration of passive immunization; immune serum contains antitoxins, a blood protein which specifically inactivates the toxin. Similar experiment was performed against diptheria. He made contribution for isolation of different organisms from pond mud by technique Known as Winogradsky column

Ronald Ross, an English physician working in the Far East in 1898 proved that mosquitoes were the vital link in malaria transmission. The discovery earned him the 1902 Nobel Prize. Another Englishman, David Bruce, isolated the cause of undulant fever. Bruce also showed that tsetse flies transmit sleeping sickness. A third British subject, Almroth Wright, described opsonins, the chemicalsubstances that promote phagocytosis in the body.In 1897, the Tokyo physician Masaki Ogata reported that rat fleas transmit bubonic plague. This discovery solved a centuries old mystery of how plague spread. A year later, Kiyoshi Shiga isolated the bacterium that causes bacterial dysentery, an important intestinal disease. The organism was later named Shigella.The American microbiologists, Daniel E. Salmon and Theobald Smith, were among the first to use heat killed bacteria for immunizations.

Salmon later studied swine plague and lent his nameto Salmonella, the cause of typhoid fever. Smith showed that Texas fever, a disease of cattle, was transmitted by ticks. The University of Chicago pathologist Howard Taylor Rickkets located the agent of Rocky Mountain spotted fever in the human bloodstream and demonstrated its transmission via ticks. Another American, William Welch, isolated the gas gangrene bacillus at his laboratory at John Hopkins University. Walter Reed led a contingent to Cuba and pinpointed mosquitoes as the insects involved in yellow fever transmission.

Alexender Flamming• Alexender Flamming a Scottish physician trained in

Microbiolgy was known for his work on host parasite interaction. Fter world war I he studied the phenomenon of phagocytosis & discovered a substance in tears, mucus and body fluids which destroyed bacteria. A colleague of Flemming named it as lysozyme- enzyme attacking bacterial cellwall (peptidoglycan).

• While working on Staphylococcus variants a number of culture plates were set apart on lab bench & examined these plates were necessarily exposed to air became contaminated with various microbes. It was noticed that around a large colony of a contaminating mold the Staphylococcus colonies became transparent & obviously under going lysis (Br. J Exp. Pathology, 10: 226-236 , 1929) Industrial production started in 1942 by Florey & Chain

Paul Ehrlich in collaboration with Sakahiro Hata, discovered the drug, Salvarsan, an arsenobenzol compound in 1910 for the treatment of syphilis caused by Treponema pallidum. Ehrlich laid important foundation of the era of chemotherapy which is defined as the use of chemicals that selectively inhibit or kill pathogens without causing damage to the victim.Gerhard Domagk of Germany in 1935 reported that Prontosil, a red dye used for staining leather, was active against pathogenic streptococci and staphylococci in mice even though it had no effect against the same infectious agent in the test tube. The two French scientists Jacques and Therese Trefonel in the same year showed that the compound Prontosil was broken down within the body of the animal to sulphanilamide (sulpha drug) which was the true active factor. Domagk was awarded Nobel Prize in 1939 for the discovery of the first sulpha drug.

The credit for the discovery of the first”wonder drug”, penicillin goes to a Scottish physician and bacteriologist, Sir Alexander Fleming (Microfocus 1.7) in 1929 from the mold Penicillium notatum. Fleming discovered the first antibiotic which is a microbial product that can kill susceptible microorganisms and inhibit their growth. Sir Howard. W. Florey and Ernst B. Chain at Oxford University in 1941 developed methods for industrial production of penicillin in England. Fleming, Florey and Chain shared the Nobel Prize in 1945 for the discovery and production of penicillin.

• At the time of World War II (1939–44), S. A. Waksman of Rutgers’ University, USA discovered another antibiotic, streptomycin along with Albert Schatz in 1944 from an actinomycete, Streptomyces griseus. Waksman received the Nobel Prize in 1952 for his notable contribution and for the discovery of streptomycin used in the treatment of tuberculosis, a bacterial disease caused by Mycobacterium tuberculosis, that had been discovered by Robert Koch in 1882. Dr. Paul R. Burkholder in 1947 isolated chloramphenicol (chloromycetin) from Streptomyces venezuelae. Dr. B.M. Dugger in 1945 Tetracyclin &1948 identified aureomycin from Streptomyces aureofaciens and terramycin was discovered by Finlay, Hobby and collaborators in 1950 from Streptomyces rimosus.

• Antibiotic production continues to be the important area of industrial research. Currently, there are over 8000 antibiotics known, of which only a few are being used as chemotherapeutic agents.

Viruses• In 1892, D. Ivanovsky, a Russian scientist, had studied

tobacco mosaic disease, in which infected tobacco plants develop a characteristic mosaic pattern of dark and light spots. He found that the tobacco plant juice retained its ability to cause infection even after it was passed through a filter. The filtration technique used by Ivanovsky would have filtered out all known bacteria, and the fact that the filtered juice remained infectious must have meant that something smaller than a bacterium and invisible to the ordinary light microscope was responsible for the disease. The filterable agent—a virus

Six years later M. Beijerinck, a Dutch scientist, realized the significance of Ivanovsky’s discovery& concluded that tobacco mosaic disease was caused by a previously undiscovered type of infective agent, a virus. In 1932, Stanley moved to the Rockefeller Institute’s Division of Plant Pathology in Princeton, New Jersey. He was primarily interested in studying viruses. Viruses were known to cause diseases in plants and animals, but little was known about how they functioned. Stanley’s assignment was to characterize viruses and determine their composition and structure. Stanley began work on a virus that had long been associated with the field of virology He was aware of recent techniques used to precipitate the tobacco mosaic virus (TMV) with common chemicals. These results led him to believe that the virus might be a protein susceptible to the reagents used in protein chemistry

1915–1917 D’Herelle and Twort discover bacterial viruses1911 Rous discovers a virus that causes cancer in chickens1950 Lwoff Induces lysogenic bacteriophages1952 Hershey and Chase show that bacteriophages inject DNA into host cellsZinder and Lederberg discover generalized transduction

• 1982 Stanley Prusiner isolates a protein from a slow disease infection and suggests that it might direct its own replication. He suggests the agent be termed a prion.

• Barry Marshall demonstrates that a bacterium, Helicobacter pylori, causes ulcers.