useful and harmful bacteria short note
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For the first half of geological time our ancestors were bacteria. Most creatures still are bacteria, and each one of our trillions of cells is a colony of bacteria. - Richard Dawkins
Bacteria - the oldest living organisms on earth - are omnipresent. The human body, the air we breathe, the surfaces we touch, the food we eat, the plants that surround us, the environment we live in, etc., are all replete with bacteria.
Almost 99% of these bacteria are helpful, where the remaining are notorious. In fact, some are essential for the proper growth of other living beings. They are either free-living or form a symbiotic relationship with animals or plants.
The list of helpful and harmful bacteria contain some of the most commonly known beneficial and deadly bacteria.
Helpful Bacteria
Lactobacillus/Döderlein's bacillus
Characteristics: Gram-positive, rod-shaped
Presence: Lactobacilli species are present in milk and dairy products, fermented foods and also form part of our oral, intestinal and vaginal microflora. L. acidophilus, L. reuteri, L. plantarum, etc., are some of the most predominant species.
Benefit: Lactobacilli are known for their ability to utilize lactose and produce lactic acid, as a metabolic byproduct. This ability to ferment lactose makes lactobacilli an important ingredient for preparing fermented foods. It is also an important part of the pickling process since lactic acid serves as a preservative. The formation of yogurt from milk is done through what is called, fermentation. Certain strains are even used commercially for the production of yogurt. In mammals, lactobacilli aid the breakdown of lactose during digestion. The resulting acidic environment prevents the growth of other microbes in the body tissues. Being so, lactobacilli are an important part of probiotic formulations.
Bifidobacterium
Characteristics: Gram-positive, branched, rod-shaped
Presence: Bifidobacteria are present in the gastrointestinal tract of humans.
Benefit: Similar to lactobacilli these are also known for lactic acid production. In addition, it also produces acetic acid. This inhibits the growth of pathogenic bacteria by controlling pH levels in the intestines. B. longum helps in the breakdown of non-digestible plant polymers. B. longum and B. infantis help prevent diarrhea, candidiasis, and other yeast infections in infants and children. Owing to these benefits, this particular species are also included in commercially available probiotics.
Escherichia coli (E. coli)
Characteristics: Gram-negative, rod-shaped
Presence: E. coli is a part of the normal microflora of small and large intestines.
Benefit: E. coli helps in the breakdown of undigested monosaccharide sugars and thus aid digestion. These bacteria produce vitamin K and biotin which are essential for a variety of cellular processes.
Note.- Certain strains of E. coli can cause severe toxicity, diarrhea, anemia, and kidney failure.