V. Early Development in Food Microbiology (Prior to 1900 A.D)

It is not known exactly when our ancestors recognized the importance of the invisible creature, now designated as microorganisms, in food. But it had to be around 8000 B.C. in the Near East after they developed agriculture and animal husbandry. They produced more foods than they could consume within the short growing season, and a portion of the produce was lost due to spoilage. They solved the problems and secured uniform food supplies throughout the year by developing different preservation technique. Between 8000 and 2000 B.C., they used drying, cooking, smoking, salting, low temperature, baking, modified atmosphere, fermentation, spices, and honey to extend the storage life of different types of raw and processed foods. Although we are not sure if they had perceptions about the cause of foodborne diseases, they definitely associated food spoilage with some invisible factors and developed successful preventative measure.
From the time of the Greeks until the discovery of biogenesis, spoilage of foods, especially of meat and fish, was thought to be due to spontaneous generation, such as the development of maggots. When the presence of different types of bacteria in many foods was discovered, their appearance through spontaneous generation was explained to be the cause of food spoilage. Schawnn (1837) and Helmholtz (1843) associated the presence of microorganisms (bacteria) in food with both putrefactive and fermentative changes of foods. However, they did not believe in spontaneous generation, but they could not explain how microorganisms could bring about those changes. Finally, Pasteur resolved the mystery by explaining that contamination of foods with microorganisms from environment and their subsequent metabolic activities and growth were the cause of fermentation of grapes, souring of milk, and putrefaction of meat.
Diseases caused by the consumption of certain foods (foodborne disease) was recognized at least during Middle Ages. Ergot poisoning in Europe was related to the consumption of grains (infested with molds) in the 12th century. In 1857, consumption of raw milk was suspected to be cause of typhoid fever. In 1870, Selmi related certain food poisoning with ptomaine (histamine). Gaertner was the forst to isolate Salmonella from a meat implicated in a foodborne diseases in 1888. Denys, in 1894, was able to establish Staphylococcus aureus with food pisioning and, in 1896, Ermengem isolatedClostridium botulinum from food. The association of many other pathogenic bacteria and viruses to foodborne was established after 19900 A.D.
Paseur, in the 1860s, rcognized the role of yeasts in alcohol fermentation. He also sowed that souring of wine was due to growth of acetic acid producing bacteria (Acetobacter aceti), and developed the pasteurization process (heating at 145˚ F for 30 min) to selectively eliminate these undesirable bacteria from wine. Like fermentation, cheese ripening was suggested by Martin in 1867 to be of microbial origin. John Lister, in 1873, was able to isolate milk-suring bacteria (Lactococcus lactis) by the serial dilution (dilution to exctinction) procedure. Cienkowski, in 1878, isolated the bacteria (Leuconostoc mesenteroides) associated with slime formation in sugar (sucrose). In 1895, microbial enumeration of milk was developed by von Geuns. After 1900 A.D., the involvement of different microorganisms in food spoilage and food fermentation was demonstrated.

IV. What are They Functions ?

The involvement of invisible organisms in many diseases in human was suspected as early as the 13th century by Roger Bacon. In the 16th century, Francostro of Verona suggested that many human diseases were transmitted by small creatures from person to person. This was also indicated by Kircher in 1658. in 1762, von Plenciz of Vienna suggested that different invisible organisms were responsible for different diseases. Schawnn (1837) and Hermann Helmholtz (1843) pointed out that putrefaction and fermentation were connected with the presence of the organisms derived from air. Finally, Pasteur, in 1875, showed that wine fermentation from grapes and souring of wine were caused by microorganisms. He also proved that spoilage of meat and milk was associated with the growth of microorganisms. Later, he showed the association of microorganisms with several disease in humans, cattle, and sheep, and later developed vaccines against several human and animal diseases, including the rabies virus. Robert Koch, in Germany (in the 1880s and 1890s), isolated bacteria in pure culture responsible for anthrax, cholera, and tuberculosis. He also developed the famous Kohc`s Postulate to associates a specific bacterium as a causative agent for a specific disease. Along with his associates, he also developed techniques of agar planting methods to isolate bacteria in pure cultures, the Petri dish (by Petri in his laboratory), and staining methods for better microscopic observation of bacteria.

With time, the importance of microorganisms in human and animal diseases, soil fertility, plant disease, fermentation, food spoilage and foodborne diseases, and other areas was recognized, and microbiology was developed as a separate discipline. Later, it was divided into several disciplines, such as medical microbiology, soil microbiology, plant pathology, and food microbiology.

III. Where are They Coming From ?

Following Leeuwenhoek`s discovery, although there no bursts of activity, some scientist minds did have the curiosity to determine the animalcules, found to be present in many different object, were coming from. Society had just emerged from Renaissance period and science, known as experimental philosophy, was in its infancy. The theory of spontaneous generations, i.e., the generation of some from of life from nonliving objects, had many strong followers among the educated and elite class. Since the time of the Greeks, the emergence of maggots from dead bodies and spoiled flesh was thought to be due to spontaneous generation. But around 1665, Redi disproved that theory by showing that the maggots in soiled meat and fish could only appear if flies were allowed to contaminate them. The advocates of spontaneous generation theory argued that the animalcules could not regenerate by themselves (biogenesis), but they were present in different things only through abiogenesis (spontaneous generation). In 1749, Needham showed that boiled meat and meat both, following storage in covered flasks, showed the presence of animalcules within a short time. This was used to prove the appearance of these animalcules by spontaneous generation. Spallanzani (1765) showed that boiling meat infusion in broth in a flask and sealing the flask immediately prevented the appearance of these microscopic organisms and thus disproved Needham`s theory. This was the time when Antonie-Laurent Lavoisier and his workers showed the need of oxygen for life. The believers of abiogenesis rejected Spallanzani`s observation, suggesting that there was enough vital force (oxygen) present in sealed flask for animalcules to appear through spontaneous generation. Later, Schulze (1830; by passing air through acid). Theodore schwann (1838; by cotton) showed that bacteria failed to appear in boiled meat infusion even in the presence of air. Finally, in 1864, Louis Pasteur demonstrated that, in boiled infusion, bacteria could grow only if infusions were contaminated with bacteria carried by dust particles in air. His careful and controlled studies proved that bacteria were able to reproduce (biogenesis) and life could not originate by spontaneous generation. John Tyndall, in 1870, showed that in a dust-free box, boiled infusion could be stored in dust-free air without microbial growth.