Taxonomy,Role and Significance of Microorganisms in food

1. Name: Samaria Saeed (16)
Taxonomy, Role and Significance of Microorganisms in Food
Taxonomy is the classification, nomenclature and identification of microbes (algae, protozoa, slime moulds, fungi, bacteria,
archaea and viruses). The naming of organisms by genus and species is governed by an international code.[T.L. Pitt and M.R.
Barer,2012]
Taxonomy and Significance of Microorganisms in Food
Because all of our foods originate from plant and animal sources, all foods will have microorganisms associated with them that
are involved in reducing the food to inorganic compounds in order to perpetuate the gas and mineral cycles on earth.
When we discuss the relative safety or potential for spoilage of a food, we need to focus on two things:
1. What are the total number of microorganisms per gram or ml?
2. What types of organisms are represented in this number?
If we know what kinds of organisms are associated with plant and animal foods in their natural state, then we can usually
predict the general types of microbes that will occur on these foods at some later stage in processing and the types of spoilage
that may occur.
In the past, classification of organisms into related groups was primarily based upon numerical taxonomy, a system that
arranged organisms on the basis of phenotypical similarities and differences among them. Today, taxonomists try to group
organisms phylogenetically, a classification scheme that mirrors evolutionary (genetic) relationships.
Criteria used to classify types of organisms include:
a. Morphological/gram stain
b. Biochemical characteristics-e.g. type of endospore, flagella, and types of substrates utilized
c. Cell wall composition. e.g. type of peptidoglycan monomer
d. Homology between 16S rRNA sequences:-16S molecule (part of the ribosome) about 1,500 bases long in bacteria
e. Serology; cell-wall antigens. e.g. group specific antigens in streptococci
f. Fatty acid profiles. Ratios of various fatty acids in the cell membrane are characteristic of different species and some
microorganisms produce unique fatty acids
g. Growth requirements
In discussions of food microbiology, another useful way to group organisms is to consider optimal growth temperatures, oxygen
requirements, and particular nutritional requirements or the nutrients that they are able to metabolize. When combined with
true taxonomy, this system allows us to identify what species of microbes we need to be concerned about in a particular food
product or process. For example, we usually do not need to worry about thermophilic species in refrigerated foods or whether
species that require O2 will spoil canned foods
[James et al.,2005]

2. Primary Sources of Microorganisms in Food:
1. Soil and Water (Air and dust) - Grouped together because of atmospheric cycling. Soil and water are common sources of
important pathogenic and spoilage microorganisms, which is why it is important to thoroughly wash raw foods with good
quality water. Air and dust are important sources of microorganisms during food processing and can influence food
quality in the home as well
2. Plants and plant products - Although most soil and water borne microbes will contaminate plants, very few types
actually persist on them. Those that persist, such as lactic acid bacteria and some yeasts, must be able to adhere to the
plant material and to utilize it for growth
3. Food Utensils - another important source for cross contamination of raw and cooked foods e.g. cutting blocks, food
trays where raw food was held (BBQ plate)
4. Intestinal tracts of humans and animals - poor sanitation practices (use of polluted water, poor personal hygiene) lead to
contamination from these sources. and many pathogens are transmitted by this route.
3. Food Utensils - another important source for cross contamination of raw and cooked foods e.g. cutting blocks, food
trays where raw food was held (BBQ plate)
4. Intestinal tracts of humans and animals - poor sanitation practices (use of polluted water, poor personal hygiene) lead to
contamination from these sources. and many pathogens are transmitted by this route
5. Food handlers - microbiota on hands, garments, etc. reflects the habits of the individual. This can include
microorganisms from virtually any environmental source
6. Animal feeds - very important source of Salmonella in poultry and of Listeria monocytogenes (from silage) in dairy and
meat animals
7. Animal hides - e.g. microbiota of raw milk influenced by that of the udder
Role of microorganisms in food
In dairy industry
From time immemorial, dairy products have been part of the human nutrition. They provide an excellent source of calcium,
vitamin D, protein and other important and essential nutrients .They also supply phosphorus, potassium, magnesium and a
variety of vitamins such as vitamin A (retinol), vitamin B12 (cyanocobalamine) and riboflavin . A variety of fermented dairy
products are prepared with various microbial strains .The main genera that belong to the lactic acid bacteria group are:
Lactobacillus, Leuconostoc, Lactococcus, Pediococcusand, Streptococcus.Microorganisms ferment the carbohydrates found
in milk, which is mostly lactose with lactic acid and some other products .Acid precipitates protein in milk, which is why
fermented products tend to be thicker than milk.
In cereal industry
Probiotic cereal-based food products and drinks containing human-made friendly microorganisms (Bifidobacterium,
Saccharomyces, Streptococcus, Enterococcus, Escherichia and Bacillus species), as well as prebiotic food products and
drinks formulations containing ingredients that cannot be digested by the human host in the upper gastrointestinal tract
(stomach and intestines) but can selectively stimulate the growth of one or a limited number of colon bacteria, have
recently entered the market .The objective of these food produce and drinks is to positively affect the composition and
intestinal microbial activities.

3. In meat and related products
Fermented meat products are a suitable environment for the growth of probiotic bacteria, but for the production of these
products, limitations must be met, such as; the natural microflora of meat, nitrite and salt, low water activity and the
absence of sugar compounds prevailed .Microbial flora in meat and meat products is affected by environmental conditions
that cause the growth of primary microorganisms in raw meat or the growth of microorganisms caused by secondary
contamination.
Preservation of food using microorganisms or their antimicrobial metabolites is called biological preservation or biological
protection . Lactic acid bacteria have a high ability to be used for biological preservation because they do not cause
problems for the consumer and prevent the growth of most microorganisms during storage
Also, the antimicrobial peptides obtained from the lactic acid of bacteria can be broken by the body’s proteases and do not
cause problems for the intestinal microbial flora. The growth of lactic acid bacteria in meat is considered a secret
fermentation because due to the low amount of carbohydrates and the buffering capacity of meat, these bacteria cannot
cause extensive changes in the taste characteristics of meat
In color production
The most important microbial colors that are produced are carotenoid pigments. Carotenoids are yellow and orange-red
pigments that exist in nature and their chemical structure has 40-carbon atoms.
Some microorganisms produce microbial dyes . The importance of this issue is because today research shows that
synthetic colors have pathogenic effects such as cancer and so on in the body, and for this reason, attention has been
directed toward the production of colors from natural sources and one of these natural sources are microorganisms
Different microorganisms around the world are capable of producing dyes, and researchers are trying to find the best
ones. Bacteria, fungi and green algae are able to produce color, and among these microorganisms, a number of species
such as Dunaleilla, Heamatococcus, Penicillium, Monascus have reached industrial production and their pigments are used
in various cases.
In removing mycotoxins produced in food
Mycotoxins are toxic and carcinogenic secondary metabolites produced by some fungi such as Aspergillus flavus. Some of
them have proven to have a carcinogenic (aflatoxin-B1), mutagenic (aflatoxins, ochratoxin A), teratogenic (patulin),
estrogenic (zearalenone)effect.Food contamination with mycotoxins is a serious problem for human and animal health.
Consumption of food contaminated with mycotoxins has been assessed as one of the causes of liver and kidney cancers in
humans and animals . The most common mycotoxin is aflatoxin, which is one of the causes of congenital abnormalities and
carcinogenesis
Since the contamination of food with mycotoxins threatens the quality of food, the detoxification of mycotoxins in order
to reduce contamination can be of significant importance to increase the safety level and control the quality of food. The
use of microorganisms to remove mycotoxins in food is considered a relatively new method for detoxification, this method
not only does not have a harmful effect on food value, but is an efficient and environmentally friendly method. Various
microorganisms such as Lactobacillus plantarum, L. acidophilus and B. subtilis have shown good detoxification capabilities
in mycotoxin-contaminated food . Therefore, microbial detoxification has shown high potential for detoxifying food on a
large scale and cost-effectively
[hassan et al.,2022]
Conclusion:

4. Microbes have been used for food purposes since antiquity. The significance of microbes has improved as a result of the growth
of food making and processing industries. Manufacturing of food and related products through microbial processes is cheaper
and easier because large-scale production and genetic modification for higher quality products are easie.A treasure of
opportunity exists for the use of microbes or their derivatives in household, village level and large-scale processing applications
in developing countries.
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