The study of Microorganisms
Microbiology is the study of microorganisms, a large and diverse group of microscopic organisms that lives in the form of isolated cells or in groups of them; it also includes viruses, which are microscopic organisms, but which lack cellular structures. Microorganisms have a huge impact on life and on the physical and chemical composition of our planet. The microorganisms are in charge of carrying out cycles of chemical elements essential for life, such as the cycles of carbon, nitrogen, sulfur, hydrogen and oxygen; microorganisms perform more photosynthesis than plants. In addition, the oceans contain 100 million more bacteria (13 × 10 28) than the stars contained in the known universe. The frequency of viral infections in the oceans is approximately 1 × 10 23 infections per second, and these infections kill 20 to 40% of bacterial cells daily. It is calculated that on earth there are 5 × 10 30microbial cells; excluding cellulose, they constitute 90% of the biomass of the entire biosphere. Humans also have a close relationship with microorganisms; more than 90% of the cells in our bodies correspond to microbes. Bacteria from the average human intestine weighs around 1 kg and an adult will excrete its own weight in faecal bacteria each year. The number of genes contained within the intestinal flora is 150 times greater than that contained in the genome and, even in our own genome, 8% of DNA comes from the vestiges of viral genomes.
Nowhere is biological diversity more evident than in microorganisms, beings that cannot be observed with the naked eye without the aid of a microscope. Regarding its form and function, be it a biochemical property or a genetic mechanism, the analysis of microorganisms leads to the limits of biological understanding. Therefore, the need for originality (a proof of the merit of a scientific hypothesis ) can be fully satisfied in microbiology. A useful hypothesis should provide a basis for generalization, and microbial diversity provides the ground where this challenge always occurs.
The prediction , that is the practical consequence of science, is a product created by a mixture of theory and technique. The biochemistry , molecular biology and genetics provide the necessary resources for the analysis of microorganisms. In turn, microbiology broadens the horizon of these scientific disciplines. Perhaps a biologist would describe this exchange as mutualism , that is, something that benefits all participants. An example of microbial mutualism is that of lichens. Lichen consists of a fungus and a phototropic partner, either an algae (eukaryote) or a cyanobacterium (prokaryote) . The phototropic component is the main producer, while the ...
According to the French biologist Jean Baptiste de Lamarck, biology studies cells based on their molecular constitution and how they cooperate with each other to form very complex organisms, such as humans. For it derives from the terms bio which means life, and logos which means study; so it is the science that studies life.
WHAT IS MICROBIOLOGY?
Microbiology is the branch of biology that is in charge of the study of microscopic organisms, it derives from three Greek words "mikros" which means small, "bios" which means life and "logos" which means study; therefore, these words together mean study of microscopic life. These beings can be made up of a single cell (unicellular), which can be eukaryotic like fungi, prokaryotic like bacteria, as well as studying viruses that are microscopic but not cellular.
TYPES OF MICROBIOLOGY
The field of microbiology can be divided into several sub disciplines:
MICROBIAL PHYSIOLOGY
Biochemically studies the functioning of microbial cells. Including growth, metabolism, and microbial structure.
MICROBIAL GENETICS
Study the organization and regulation of microbial genes and how they affect the functioning of cells. It is closely related to molecular biology.
CLINICAL MICROBIOLOGY
Study all the microorganisms that cause pathologies in living beings.
MEDICAL MICROBIOLOGY
Studies the microorganisms that cause human pathologies (diseases), for example: Streptococcus agalactiae that causes sepsis (generalized infection) in newborns.
ENVIRONMENTAL MICROBIOLOGY
Study the role and diversity of microbes in their natural environments. They include microbial ecology, geomicrobiology, microbial diversity, and bioremediation.
VETERINARY MICROBIOLOGY
Study the bacteria and microbes that come to directly affect animals.
Study the evolution of microbes. They include bacterial systematics and taxonomy.
INDUSTRIAL MICROBIOLOGY
Studies the exploitation of microbes for use in industrial processes. Examples are: wastewater treatment and industrial fermentation for brewing beer or yogurt.
Microbiology is the science that studies microorganisms, bacteria, fungi, protists and parasites and other agents such as viruses, viroids and prions. Microorganisms fulfill essential functions in all ecosystems; establishing mutualistic, parasitic or neutral relations between them and with other organisms. For thousands of years, these organisms have been used for food production and currently have the greatest potential for biotechnological use given their metabolic diversity.
Microbiology is a science in the process of expansion. As we discover the enormous diversity and potential of microorganisms, new lines of work such as phage therapy, exobiology, synthetic biology, among others, continually emerge. It is estimated that only 1% of the existing microorganisms are known, a situation that offers an enormous opportunity for research and technological development. Various techniques are used to study microorganisms, ranging from laboratory procedures that were implemented more than a century ago, to recombinant DNA, genomic and nanotechnology techniques that have expanded the vision of the microbiological world in the last decade. Microorganisms are of great interest due to their clinical, environmental and biotechnological importance. Some of them are causative agents of various infectious diseases (AIDS, tuberculosis, Chagas disease, some cancers, various diseases in plants and animals, etc.) and others produce compounds that fight infections (antibiotics). In the environmental field they are used for the development of clean and sustainable technologies, such as the production of biofuels and agricultural bio-inputs, and bioremediation, biological control and recycling processes. In the food industry they are essential in the production of wines, cheeses, bread, among others, but they can also cause food spoilage. Microbiology allows to know the world of microorganisms, understand their importance and take advantage of the diversity of their functions to improve the quality of life of man. Chagas disease, some cancers, various diseases in plants and animals, etc.) and others produce compounds that fight infections (antibiotics). In the environmental field they are used for the development of clean and sustainable technologies, such as the production of biofuels and agricultural bio-inputs, and bioremediation, biological control and recycling processes. In the food industry they are essential in the production of wines, cheeses, bread, among others, but they can also cause food spoilage. Microbiology allows to know the world of microorganisms, understand their importance and take advantage of the diversity of their functions to improve the quality of life of man. Chagas disease, some cancers, various diseases in plants and animals, etc.) and others produce compounds that fight infections (antibiotics). In the environmental field they are used for the development of clean and sustainable technologies, such as the production of biofuels and agricultural bio-inputs, and bioremediation, biological control and recycling processes. In the food industry they are essential in the production of wines, cheeses, bread, among others, but they can also cause food spoilage. Microbiology allows to know the world of microorganisms, understand their importance and take advantage of the diversity of their functions to improve the quality of life of man. In the environmental field they are used for the development of clean and sustainable technologies, such as the production of biofuels and agricultural bio-inputs, and bioremediation, biological control and recycling processes. In the food industry they are essential in the production of wines, cheeses, bread, among others, but they can also cause deterioration in food. Microbiology allows to know the world of microorganisms, understand their importance and take advantage of the diversity of their functions to improve the quality of life of man. In the environmental field they are used for the development of clean and sustainable technologies, such as the production of biofuels and agricultural bio-inputs, and bioremediation, biological control and recycling processes. In the food industry they are essential in the production of wines, cheeses, bread, among others, but they can also cause deterioration in food. Microbiology allows to know the world of microorganisms, understand their importance and take advantage of the diversity of their functions to improve the quality of life of man. bread, among others, but can also cause spoilage in food. Microbiology allows to know the world of microorganisms, understand their importance and take advantage of the diversity of their functions to improve the quality of life of man. bread, among others, but can also cause spoilage in food. Microbiology allows to know the world of microorganisms, understand their importance and take advantage of the diversity of their functions to improve the quality of life of man.
Microorganisms colonize much of the surface of the human body that is in direct contact with the external environment, but also internal surfaces. The intestinal ecosystem is a complex environment in which dynamic and reciprocal interactions occur between the epithelium, the immune system, and the local microbiota. It is estimated that between 500 and 1000 species of microorganisms coexist in a delicate balance in the gastrointestinal tract. These can make up the local microbiota or be transit microorganisms, such as those that enter with food. The digestive tract is colonized by bacteria from birth. The stomach and the first portion of the intestine are not ideal sites for the establishment of commensal bacteria due to the pH ranges and the presence of digestive enzymes, making the large intestine the most colonized site in the gastrointestinal tract. The composition of the intestinal microbiota varies throughout life and with the nutritional and physiological conditions of the host. The intestinal immune system matures as the agents that make up the microbiota become established. The microorganisms of the generaEnterococcus, Lactobacillus, and Clostridium are early colonizers; They installed after Bacteroides, Bifidobacterium, Streptococcus and other members of the family Enterobacteriaceae , among others .
Commensal bacteria produce signals picked up by the innate immune system and thus collaborate with the integrity of the intestinal barrier. The microbiota increases the resistance of an organism in the presence of pathogens, since it hinders its access to the intestinal surface. In addition, it plays important roles in the bioavailability of nutrients, the metabolism of carbohydrates and proteins and in the development, maturation and maintenance of the sensory and motor functions of the gastrointestinal tract, among others . A healthy microbiota is one that has great microbial diversity and ability to resist physiological stress. An alteration in its composition or dysbiosis can predispose to local or other parts of the body, such as diarrhea, autoimmune phenomena, allergies, irritable bowel syndrome, inflammatory bowel disease, obesity and colon cancer .
Scientific interest in the gut microbiota has fueled research that demonstrated the existence of beneficial microorganisms that could be used to influence the activity of harmful microorganisms. In this sense, the incorporation through the diet of non-native bacterial species, beneficial for the gastrointestinal tract, constitutes an interesting option to contribute with a local microbial balance and prevent diseases . The first studies on this type of organisms were carried out in 1607 by Nobel laureate Elie Metchnikoff, who discovered the beneficial effect of fermenting bacilli present in dairy derivatives (such as Lactobacillus ) and recommended their ingestion .
The UN Food and Agriculture Organization of the United Nations [ Food and Agriculture Organization of the United Nations (FAO)] and the World Health Organization [ The World Health Organization (WHO)] defines probiotics as "live microorganisms which, administered in adequate doses, they confer beneficial effects on the health of the consumer » . Through the work of a panel of experts, the International Scientific Association for Probiotics and Prebiotics (ISAPP) defined different categories of living microorganisms for human use: the "non-probiotics", which corresponds to any food containing microorganisms in fermentation process with 1x106 colony forming units (CFU) per serving, but whose specific efficacy has not been proven and require further study; and the "probiotics", divided in turn into three categories:
- I)
Probiotics present in foods or supplements that are not used for a specific purpose. These can be strains that belong to a safe species when administered and with sufficient evidence of a beneficial effect on consumer health; they must have been the subject of observational, systematic or meta-analysis studies that confirmed this effect for the taxonomic category in question.
- II)
Probiotics in foods or supplements with a specific effect on the health of the consumer, duly verified and evidenced from studies conducted in humans.
- III)
Probiotics as drugs or biotherapeutic agents, which present a specific effect for which they are indicated for the treatment or prevention of diseases and which are regulated as medications .
The so-called "functional foods" not only provide nutrients, but also aim to improve different functions for the consumer . Different species of lactic acid bacteria (BAL), Bacillus and fungi of the genera Aspergillus and Saccharomyces have been used in the industrial production of probiotics throughout the last decades. Currently, most of these belong to the genera Lactobacillus, Streptococcus, Bifidobacterium and Lactococcus .
As a result of certain irregularities arising in the scientific and commercial field, the ISAPP has established four sine qua non conditions that all microorganisms must fulfill to be considered a probiotic, these are the following: 1) maintain its viability during administration; 2) that the benefits in the host that consumes them are duly corroborated; 3) that the microorganism / s have a defined taxonomic category (genus, species and strain); and 4) that its use is safe . This last point is extremely important, since undesirable adverse effects such as bacterial translocation towards the systemic circulation must be avoided, the consequences of which can be serious .
Probiotic safety tests include in vitro analyzes of antimicrobial sensitivity from the determination of the minimum inhibitory concentration (MIC) and detection of hemolytic and enzymatic activities, which are related to the ability to invade and cause tissue damage. (presence of collagenases, glycosidases, gelatinases, etc.). Genome sequencing is a very useful tool in identifying virulence factors not expressed in phenotypic terms . As virulence is a complex phenomenon that involves active interaction between the microorganism and the host, in vivo tests are useful in evaluating safety . Although the rodent model is widely used, it is important to note that there are differences with respect to the human gut microenvironment. Outside of the ethical considerations that go beyond this article, it is important to highlight that the pig is the animal that best reproduces what occurs in the human gastrointestinal tract .
The introduction of paraprobiotics alleviates the safety problem in the administration of probiotics. Paraprobiotics are "non-viable microorganisms (intact or lysed), or crude extracts of cells, which, administered orally or locally in adequate doses, confer benefits to the health of the consumer". The cellular structures of probiotics or paraprobiotics, when isolated and purified, remain as immunogenic fragments called "probiotic cell fragments" or FCP. The bacteria used in the technology of cell fragments of probiotics lack pathogenic potential and are within the European Union novel food regulation standards. Both probiotics, paraprobiotics, and FCPs are providers of pathogen -associated molecular patterns (MAMPs), as they activate the respective pattern recognition receptors (PRRs) of innate immunity. . Probiotic bacteria of the genera Lactobacillus andBifidobacterium have obtained GRAS status ( generally recognized as safe). However, the possibility of using dead bacteria or cell fragments of probiotics is especially promising, since this could exploit the probiotic properties of bacteria from other genera, such as Streptococcus, Bacillus or Enterococcus , which are considered opportunistic pathogens .
It is common to generalize about the side benefits of consuming probiotics. The ISAPP panel of experts grouped the different mechanisms of action of probiotics according to their type between strain-specific, dependent on microbial species or universal. Among the former, considered very rare, effects were found on the nervous, immune and endocrine systems and on the production of specific bioactive substances. More common were those actions observed in probiotics that belonged to the same microbial species, such as vitamin synthesis, reinforcement of the intestinal barrier and effects on the metabolism of bile salts, enzymatic activity and the neutralization of carcinogenic substances .
Many probiotic microorganisms have been shown to limit infection by different infectious agents (Rotavirus, Norovirus, Escherichia coli, Salmonella, Campylobacter, Clostridium difficile and parasites such as Cryptosporidium , Toxocara canis , among others) . This function may be due, depending on the case, to competition for nutrients or receptors, to the modulation of the immune system, to the action of products of microbial metabolism, such as fatty acids, or to the secretion of peptides called bacteriocins .
Bacteriocins comprise a large and diverse group of antimicrobial proteins or peptides synthesized in ribosomes, which have a bactericidal or bacteriostatic effect on strains of the same species or of other genera. Bacteriocins are produced by various bacterial species, but of particular interest are those produced by BALs, which are the most widely used in the food industry .
BAL bacteriocins are considered natural biopreservatives and are of great interest to the food industry. The antimicrobial capacity of these peptides, combined in certain groups of bacteriocins with other qualities such as low molecular weight, hydrophobicity, and stability in wide temperature ranges, position them as a potential novel tool in the prevention and treatment of different infectious diseases, alone or in combination with conventional antimicrobial agents .
Fecal microbial transplantation is another procedure currently being considered to reverse dysbiosis processes. It is about incorporating fecal bacteria from a healthy donor to a patient with a specific pathology. It has recently been successfully applied in patients with Clostridium difficile infection . However, some progress is still required in this area for its acceptance and application in medical practice .
In conclusion, the advances in the knowledge of the intestinal microbiota will allow us to elucidate its importance in the local and general homeostasis of the organism. Although we expect more, great progress has been made in relation to probiotics and related drugs in the last 100 years, both scientifically and normatively and regulatoryly, which in an interrelated manner allow us to discern and clarify aspects that initially seemed to be under frosted glass. On the other hand, it is important to highlight the social acceptance that is perceived around the beneficial effect of the consumption of probiotics.
The use of probiotic and related microorganisms allows reestablishing gastrointestinal homeostasis, thus generating not only local but general impacts, making them useful as supplements to specific therapies. The respective fields of paraprobiotics, cell fragment technology, bacteriocins, and faecal microbial transplantation show promise. The use of fragments of microorganisms or dead bacteria is attractive due to its greater safety, particularly if you want to apply it to patients with impaired immunity, by completely avoiding the risk of bacterial translocation.
Comments
Post a Comment