- Industrial microbiology is the study of the large-scale, profit-driven production of microbes or their products for direct use or as inputs in the creation of other items.
- Thus, yeasts can be grown for direct human consumption, as animal feed, or for use in bread production; their byproduct ethanol can be consumed in the form of alcoholic beverages or employed in the production of perfumes, pharmaceuticals, etc.
- Clearly, industrial microbiology is a subfield of biotechnology that incorporates both conventional and nucleic acid components. The 1992 United Nations Conference on Biological Diversity (Earth Summit) in Brazil defined biotechnology as “any technological application that uses biological systems, live creatures, or derivatives thereof to manufacture or modify products or processes for specific use.”
- Examples of biotechnology include the utilisation of microbes to manufacture the antibiotic penicillin, the dairy product yoghurt, amino acids, and enzymes.
- In the last two decades or more, advances in molecular biology have substantially expanded our understanding of nucleic acids in genetic processes.
- This has led to applications of molecular-level biological modification in technologies such as genetic engineering.
- All aspects of biological manipulations now involve molecular biology, and it seems practical to divide biotechnology into traditional biotechnology, which does not directly involve nucleic acid or molecular manipulations, and nucleic acid biotechnology, which involves the manipulation of nucleic acids and their products.
Introduction of Industrial microbiology
- Industrial microbiology is an important discipline of microbiology that focuses on those elements of microbiology that include economic considerations, such as the preparation of useful products from inexpensive and frequently disposable substrates.
- Therefore, the industrial microbiologist is now able to compete with the industrial chemist. With the exception of one or two antibiotics, fermentative production costs are significantly lower than synthetic production costs.
- There were issues with the disposal of various byproducts from particular industries (e.g. cheese whey from the cheese industry).
- These issues were resolved by fermentation industries (e.g. acetic acid production by the use of whey). In this case, microbial activity affects the conversion of the substrate into the desired product (i.e. bioconversion).
- In certain instances, bulk production of microorganisms is necessary (i.e. biomass production). Microbes such as viruses, bacteria, actinomycetes, yeasts, fungi, and algae are useful to industrial microbiologists.
- For fermentation industries, unique strains are developed. Microbes are actually prevalent in natural sources such as soil and water. From natural isolates, production strains are derived to optimise fermentation operations.
- This is achieved by means of progressive genetic selection. Industrial microbiology can be comprehended by revealing only the usefully applied features of numerous microbiology subfields.
- In other words, industrial microbiology is comprised of selected branches of microbiology directly or indirectly involved in human services.
- The industrial microbiologist and biochemical engineer are mutually dependent on one another. The biochemical engineer is responsible for controlling all remaining bioparameters of the fermentation process, excluding those related to culture. Therefore, both a biochemical engineer and a microbiologist are needed to optimise a fermentation process.
- Recently, computers have been implemented in fermentation processes. This has been beneficial to the diligent research microbiologist and biochemical engineer.
- With this application of computer systems, optimising the various bioparameters has become quite simple. Biotechnology advancements and the computerization of fermentation processes have brightened the outlook for industrial fermentations.
- The evolution of any fermentation process necessitates consistent experimentation and perseverance. No book can provide detailed data about fermentation methods, since such details are trade secrets. Consequently, microbiological businesses are distinct from chemical and similar sectors. In other words, building new fermentation plants requires experimenting.
- Typically, industrial uses of microorganisms fall into one of two categories:
- those that employ a pure culture or pure cultures with large-scale manufacturing procedures.
- Those entail the use of naturally existing microbe combinations under settings that may be relatively primitive in order to produce a desired modification in some industrially valuable goods (e.g. sauerkraut).
History and Development in industrial microbiology
The history of the evolution of industrial microbiology can be neatly categorised into three time periods:
- A period of ignorance (pre-1800).
- A period of discovery (1800-1900).
- A period of industrial development (post-1900).
Since antiquity, many of man’s domestic processes have relied on fermentative changes. For instance, the first bread was made circa 4000 B.C. Moreover, wine was made from grapes, and brewing beer possessed the characteristics of a profession. In hindsight, the creation of the microscope and the discovery of live microorganisms in the eighteenth century mark the end of the time of ignorance. By the turn of the twentieth century, fermentation processes had already begun to be industrialised.
1. The Era Of The Discovery Of Microbes
Roger Bacon described a lens in 1267, while Salvino D’Armati (d. 1317) is credited with inventing spectacles. However, the microscope was not invented until almost three centuries later. Zaccharias Jensen, while working with his father (a maker of eyeglasses) during the years 1591 to 1608, joined two lenses to create a rudimentary compound microscope. This instrument lacked any means of focusing. Galileo Galilei’s compound microscope, which he dubbed the occiale and which he created in 1610, featured a focusable tube. According to his own description, a water flea beneath it resembled a chicken in size. Fabri offered the name microscope for the first time in 1625. In 1650, Huygens invented the eyepiece lens system that carries his name and is basically identical to that used in the vast majority of current microscopes.
Hooke, the great British microscopist, originally used the term cell to the box-like formations he observed in thin sections of cork under a compound microscope and described them in Micrographia (1665). These developments paved the way for the discovery of the world of microorganisms. However, prior to Antony van Leeuwenhoek’s use of a rudimentary microscope, the existence of microorganisms was entirely based on philosophical speculation.
Around 1670, Antonie van Leeuwenhoek (1632-1723) began making small microscopes as a hobby. He was a Dutch trader from Delft, Netherlands. Throughout his lifetime, he produced over 250 microscopes. These consisted of brass and silver-mounted, custom-ground lenses. Consequently, Antony van Leeuwenhoek was able to achieve magnifications of up to 160 diameters (some commentaries say 270 diameters). His descriptions of protozoa were so precise that a number of kinds were readily identifiable.
For him, nothing was too holy to be observed. He utilised his microscope to examine a vast array of chemicals. In a series of letters to the British Royal Society, Leeuwenhoek meticulously documented his findings.
In one of the letters dated September 7, 1674, he described the ‘very small animalcules’ that we now refer to as free-living protozoa. On October 9, 1676, he composed the following: “In 1675, I discovered living organisms in rainwater that had been sitting in a blue-glazed earthenware vessel for only a few days. This prompted me to observe the water with great care, especially the tiny creatures that appeared to be ten thousand times smaller than those visible to the naked eye.”
There is no doubt that Leeuwenhoek examined bacteria, fungi, and other types of protozoa, as he reported his observations in great detail. For instance, on June 16, 1675, while analysing well water in which he had soaked peppercorns the day before, he reported: “In a single drop of water, I discovered a large number of tiny organisms of various sizes and varieties. They moved with bendings, like an eel, always swimming with its head in front and never its tail, but these animalcules also went backwards and forwards, albeit very slowly.”
Leeuwenhoek stressed, in addition to the diversity of this microbial world, its tremendous quantity. In one letter explaining the unique bacteria of the human mouth for the first time, he wrote: “Several ladies who visited my home were interested in seeing the eels in vinegar, but several of them were so repulsed by the sight that they promised to never use vinegar again. But what if one were to inform such individuals in the future that there are more critters living in the filth on a man’s teeth than there are men in an entire kingdom?”
Until his death in 1723, Leeuwenhoek communicated his discoveries to the Royal Society through an extensive series of Dutch-written letters. These letters were translated and published in English in the Royal Society’s proceedings. Consequently, his discoveries were rapidly and broadly shared. While Leeuwenhoek may not have been the first to observe bacteria under a microscope, he was the first to accurately describe these forms and probably the first to grasp the microscope’s potential as a scientific device.
2. The Era of discovery
Fermentation was regarded a chemical process during the middle of the twentieth century. The chemist Liebig described the process as being dependent on a chemical ferment, an alterable substance that decomposes and stimulates chemical change, i.e. fermentation in a ground substance. It was assumed that the dissolution of a ferment caused a disturbance among the molecules that led to the fermentation-related alterations. According to this theory, chemical instability was the main cause of fermentation.
Regarding alcoholic fermentation, several chemists of the time, like Berzelius (1779-1848) and Bertholet (1843-1907), held similar ideas. Schwann described alcoholic fermentation as a yeast-dependent process in 1837, but none of the top chemists of the period seriously contemplated the notion of a live organism as the fermentation agent.
Pasteur pursued Schwann’s hypothesis and became a pioneer in experimental fermentation experiments. He corroborated Schwann’s observation and demonstrated that yeast, a living organism, is essential for the chemical reaction that converts sugar into alcohol and carbonic acid. Pasteur found in 1857 that a separate type of bacteria was involved in the transformation of carbohydrates into lactic acid. These discoveries led Pasteur to the conclusion that microorganisms of some sort are necessary for all types of fermentation.
Pasteur isolated microorganisms linked with fermentation and grew them in nutrient solutions. These microorganisms were then introduced into the appropriate natural media from which the native organisms had been removed and fermentation was established experimentally. It was determined that a temperature range of 30 to 50 degrees Celsius was optimal for the process.
Pasteur meticulously observed the fermentation cycle. He repeatedly removed the organisms from fermenting cultures, transferred them to other sterile media, and discovered that fermentation always occurred when the required species and conditions were present. At the conclusion of the experiment, Pasteur recognised the substances that had been generated. He then detailed the chemical transformations necessitated by organisms engaged in the conversion of sugar to lactic acid.
Under a microscope, several species were studied and their properties were meticulously noted. In several aspects, lactic acid microbes resembled those linked with alcoholic fermentation. Recent research has demonstrated that the two types of creatures are not as closely linked as Pasteur believed. The creature that produces lactic acid is a bacteria, not a yeast.
Thus, it has been demonstrated that distinct types of microbes are responsible for distinct types of fermentation. When brewer’s yeast was introduced to a normal medium containing sugar, alcoholic fermentation would begin; however, lactic acid organisms added to a similar media would produce lactic acid. During the subsequent twenty years (1857-1877), Pasteur explored a variety of additional fermentable substances and established himself as an expert in the field. In 1858, he determined that the organism responsible for the fermentation of ammonium tartrate was a mould. Now that yeasts, bacteria, and moulds had been associated with fermentation, Pasteur’s 1860 memoir on alcoholic fermentation remains a classic on the subject.
Pasteur (1861) examined the fermentation of butyric acid and made the significant finding that fermentation can occur in the absence of oxygen. Pasteur thought the rod-shaped creature associated with butyric fermentation to be animal in nature and gave it the name vibrio. Pasteur noted, when examining a drop of fluid culture containing butyric vibrio under a microscope, that the organisms at the drop’s edge, where they came into contact with air, were inactive, and those in the drop’s centre were vigorously motile.
He hypothesised that the presence of oxygen inhibited the growth and activity of these organisms. Pasteur noted that all action was halted when he passed a stream of oxygen through an active butyric fermentation culture to test the idea. Aerobic and anaerobic are the terms used to differentiate between the two types of organisms. Also in 1861, Pasteur published his findings on the fermentation of acetic acid. In 1862, he demonstrated that this fermentation was carried out by organisms of the genus Mycoderma, which he had extensively investigated.
The results of a comprehensive research of vinegar preparation were published in 1864 and 1868. Pasteur was then asked by his former professor, J.B. Dumas, and Napoleon Ill to investigate the problem of sour wine, which threatened the vital French wine industry. He pursued the inquiry with vigour and zeal, and in 1866 he wrote an outstanding wine memoir.
This 264-page treatise addressed the so-called illnesses of wine, which Pasteur attributed to invading foreign organisms that affected the wine’s chemical and physical qualities. Pasteur demonstrated that unwanted organisms might be eliminated by partly sterilising wine-making juice at a temperature below the boiling point. This was insufficient to remove the juice’s beneficial effects. Then, from pure cultures, other organisms capable of creating desirable traits might be introduced.
The method, which is now known as pasteurisation, was then used to milk in order to eliminate the vast majority of natural organisms and all pathogens, such as tuberculosis, brucellosis, and typhoid germs. In 1871, Pasteur resumed his studies of fermentation, this time focusing on the fermentation of beer. The results were presented in 1876 in a thorough, nearly 400-page document that not only discussed the results of research on beer, but also summed up Pasteur’s broad knowledge to support his theory that the fermentation process was based on live creatures.
The proposed explanation of fermentation was disputed once more, this time by Liebig, who developed a modified version of his earlier hypothesis in which enzymes were proposed to be responsible for fermentation. However, enzymes could not be shown, and Pasteur’s theory that live creatures were responsible for the process ultimately gained credence.
3. The Era Of The Discovery Of Antibiotics
German scientists Emmerich and Low discovered an antibacterial compound from bacteria at the turn of the twentieth century. This compound was known as pyocyanase. It was able to eliminate microorganisms that produce discase. Consequently, the initial antibiotic was identified. Unfortunately, there were no ways available to ensure the quality of each batch, and the project was abandoned because it was deemed too unreliable. The main advancement in the field of antibiotics began thirty years after the accidental discovery of penicillin. Sir Alexander Fleming (1881-1955), a British bacteriologist, noticed that bacterial growth was hindered in the vicinity of a mould colony on a plate culture of contaminated bacteria.
In 1928, he conducted his trials at St. Mary’s Hospital in London. 1929 saw the publication of his findings in the Journal of Experimental Pathology. He named the antibiotic chemical penicillin since the mould was a strain of Penicillium (P. notatum). Fleming did not follow the inquiry further due to a lack of time and funds; instead, he simply shelved his discovery in the hope that it might be examined in the future. A decade later, his hopes were realised when two further Englishmen, Chain and Florey, joined Fleming’s investigations.
Thus, an antibiotic formulation for human usage was produced. In 1942, commercial production in massive, mechanically agitated and aerated fermentors began in the United States as a result of the rapid resolution of the challenges inherent to large-scale, submerged, aerobic cultivation of microorganisms. This immediately spawned a similar trend in the United Kingdom.
Dubos, working at the Rockefeller Institute at the same time, identified a series of microbial compounds that he named tyrothricin. His formulation comprised gramicidin and tyrocidine, as determined by further analysis. These were discovered to be beneficial for treating infections in humans. Similar research was being conducted at Rutgers University, where Dr. S.A. Waksman conducted a systematic search for antibacterial compounds in a collection of soil-dwelling Streptomyces microorganisms.
Actinomycin was isolated by Waksman and his colleagues in 1940, streptothricin in 1942, streptomycin in 1943, and neomycin in 1949. The discovery of streptomycin dramatically accelerated Streptomyces’ search for effective antibiotics. This group of microorganisms is the source of numerous antibiotics currently in use.
Ehrlich isolated chloromycetin (chloramphenicol) for the first time in 1947. A year later, Duggar described aureomycin. This even presented new opportunities for the search and discovery of a significant class of antibiotics known as tetracyclines. As a result of these discoveries, the rate of subsequent discoveries quickened.
4. A Century Of Growth Of Industrial Fermentations
There has been a great advancement in the field of industrial fermentations over the past fifteen years. This growth is both qualitative and quantitative in nature. In other words, both the quantity of products produced on a commercial scale and the capacity of industrial fermentations have increased. Thus, the number of items has expanded by more than twofold, while the volume has increased by around fivefold.
More than 500 businesses use fermentation technologies in their production operations. In 1880, a small-scale lactic acid production facility was established in Avery, Massachusetts, marking the beginning of the fermentation industry in the United States and the majority of the industrialised world. During the original phase of development (1880-1910), fermentation products had immediate applications in the food industry (lactic acid and baker’s yeast) and in the textile industry (ethanol) (amylases for desizing of textiles).
Although fermentation industries flourished, several techniques were based on experience rather than science. Therefore, the element of “practical witchcraft” hindered the advancement of science. From 1914 through 1918, the wartime demand for acetone prompted some practical research. From 1920 to 1940, this led to the construction of a solid scientific foundation for the growth of fermentation industries.
The Weizmann process (acetone-butanol fermentation) required the combined efforts of biochemists, engineers, bacteriologists, and chemists to bring this rather complex fermentation from the laboratory scale to the production scale, and emphasised the importance of sterile media, pure culture technique, and knowledge of bacterial physiology. This experience highlighted the importance of a team-based approach to solving fermentation issues.
After World War I, the development of chemical industries in the United States had a stimulating effect on the fermentation industries, as efforts were made to develop new and distinct techniques from those already in use in Europe. The early success of mycological (mould) processes for the generation of citric acid and gluconic acid, as well as the ongoing success of the acetone-butanol fermentation process, persuaded some chemical manufacturers that microbial methods might be reliable and profitable.
The desire to augment human and animal diets with vitamins prompted the quest for a fermentation process for riboflavin, thiamine, ascorbic acid, and other substances with medicinal applications. The initial findings on penicillin showed that this microbial product could have a significant impact on the treatment of infectious disorders.
The period between 1945 and 1960 witnessed the expansion of fermentation technology for the synthesis of antibiotics, enzymes, and other organic acids with enormous commercial potential. Microbial processes for glutamic acid and lysine; commercial production of anti-inflammatory agents such as cortisone, hydrocortisone, prednisolone and triamcinolone, based on selective microbial oxidation of the 1, 2-cyclopentenophenanthrene nucleus; and large-scale preparation of yeast and other organisms as protein sources for human and animal diets were among the most remarkable practical developments.
Approximately 50 antibiotics, as well as a number of enzymes, polysaccharides, flavor-enhancer purine nucleosides, microbial insecticides, and scents, are on the list of novel fermentations that were triggered between 1960 and 1980. More than fifty percent of the protein-coagulating proteases employed in cheese production in the United States in 1980 were mould enzymes.
These have replaced and complemented the restricted quantity of rennet generated from calf stomach for this purpose. For example, Mucor miehei produces the enzyme marzyme. Currently, numerous cheese industries use it for milk coagulation.
References
- Najafpour, G. D. (2007). Industrial Microbiology. Biochemical Engineering and Biotechnology, 1–13. doi:10.1016/b978-044452845-2/50001-x
