What is Bacteria: Definition and 157 Discussions

Bacteria ( (listen); common noun bacteria, singular bacterium) are a type of biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods and spirals. Bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste, and the deep biosphere of the earth's crust. Bacteria also live in symbiotic and parasitic relationships with plants and animals. Most bacteria have not been characterised, and only about 27 percent of the bacterial phyla have species that can be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology.
Nearly all animal life is dependent on bacteria for survival as only bacteria and some archaea possess the genes and enzymes necessary to synthesize vitamin B12, also known as cobalamin, and provide it through the food chain. Vitamin B12 is a water-soluble vitamin that is involved in the metabolism of every cell of the human body. It is a cofactor in DNA synthesis, and in both fatty acid and amino acid metabolism. It is particularly important in the normal functioning of the nervous system via its role in the synthesis of myelin. There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water. There are approximately 5×1030 bacteria on Earth, forming a biomass which is only exceeded by plants. Bacteria are vital in many stages of the nutrient cycle by recycling nutrients such as the fixation of nitrogen from the atmosphere. The nutrient cycle includes the decomposition of dead bodies; bacteria are responsible for the putrefaction stage in this process. In the biological communities surrounding hydrothermal vents and cold seeps, extremophile bacteria provide the nutrients needed to sustain life by converting dissolved compounds, such as hydrogen sulphide and methane, to energy.
In humans and most animals, the largest number of bacteria exist in the gut, and a large number on the skin. The vast majority of the bacteria in the body are rendered harmless by the protective effects of the immune system, though many are beneficial, particularly in the gut flora. However, several species of bacteria are pathogenic and cause infectious diseases, including cholera, syphilis, anthrax, leprosy, and bubonic plague. The most common fatal bacterial diseases are respiratory infections. Tuberculosis alone kills about 2 million people per year, mostly in sub-Saharan Africa. Antibiotics are used to treat bacterial infections and are also used in farming, making antibiotic resistance a growing problem. In industry, bacteria are important in sewage treatment and the breakdown of oil spills, the production of cheese and yogurt through fermentation, the recovery of gold, palladium, copper and other metals in the mining sector, as well as in biotechnology, and the manufacture of antibiotics and other chemicals.Once regarded as plants constituting the class Schizomycetes ("fission fungi"), bacteria are now classified as prokaryotes. Unlike cells of animals and other eukaryotes, bacterial cells do not contain a nucleus and rarely harbour membrane-bound organelles. Although the term bacteria traditionally included all prokaryotes, the scientific classification changed after the discovery in the 1990s that prokaryotes consist of two very different groups of organisms that evolved from an ancient common ancestor. These evolutionary domains are called Bacteria and Archaea.

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  1. F

    Total movement of bacteria assuming a random distribution

    Hello, I have to find an expression for the total movement of a bacteria ##s##, knowing that the bacteria is placed (centered) on a two side ruler at position ##x=0## (so a negative ##x## value means the bacteria has moved to the left of the ruler) and that the probability it moves to ##x## is...
  2. Astronuc

    Beware of Vibrio bacteria in warm water: Gulf and Atlantic Coast areas

    Bailey's death came days after he handled crabs, one which pinched his finger causing a cut. Some vibrio bacteria entered the fresh wound into the blood stream. Since 2007, reports of illness from toxic forms of vibrio have tripled in South Carolina and nearly doubled in North Carolina...
  3. DaveC426913

    Bacteria, mold and household water

    I live in a house that's 91 years old. I had the pipes replaced with copper a few decades ago, but its still an old house. Occasionally, I have to unscrew the aerator on the kitchen faucet and shake out the mineral grains. They're always red (pres. iron oxide). This time, I wiped my finger...
  4. BillTre

    Electrically Conducting Bacteria

    This news article in Science magazine describes what is becoming known about the different kinds of bacteria that can do this, what is known about how they do it, and how people might make use of the phenomena. The bacteria conduct electricity through either small nano-filaments sticking out...
  5. littledog

    Why is it difficult to stain dormant bacteria with Nucleic acid dyes?

    I found that it's difficult to stain dormant bacteria or bacteria in lag phase with Nucleic acid dye like SYTO9/SYBR Green Ⅰ, does anyone know why? DNA 3D structure too complex? DNA binding protein too much? Low material transport efficiency in bacteria? Or anyother factors? Is there any...
  6. mark!

    Why do bacteria insert their genes into a host?

    "Acute myeloid leukaemia cells were particularly rife with bacterial sequences. A third of the microbial genes came from a genus called Acinetobacter, and had been inserted into the mitochondrial genome. "Stomach cancer cells also contained lots of bacterial DNA, especially from Pseudomonas...
  7. C

    Preventing Bacterial Growth in Raw Meat: Tips for Safe Thawing and Storage

    We know that meats in freezer can be thawed safely by putting it in the lower refrigerator then cooking it directly without thawing by putting at room. This is because bacteria can grow if not very cold. How about those meat newly bought at market? How long before bacteria grow in them if you...
  8. I

    If bacteria didn't have any food, would it die?

    Hi! Is there any research or experiments that show what happens to bacteria that in normal conditions end up without any food to consume? Do they continue to exist? And if yes, in which form? Many thanks for any thoughts
  9. enorbet

    Medical DNA of Gut Bacteria Scores Hits in Autism?

    Greetings Since genome sequencing is apparently having a major impact on medical science, just to name one field, I am interested in hearing/reading more about this recent event regarding autism. It seems to me this could have far-reaching implications and possibly major impact on how we view...
  10. A

    Light intensity at a distance -- UV light to kill bacteria

    I have obtained seeds of a rare rhododendron species. These seeds are contaminated (experimentally determined). While I have tried several common methods, none decontaminated the seeds. Lately, I have read that so many joules of UV light at approximately 254nm will prevent replication and...
  11. Auto-Didact

    Quantum Entangled Living Bacteria

    "Schrödinger's Bacterium" Could Be a Quantum Biology Milestone I can't believe I'm only seeing this article now. Achieving quantum mechanical effects with large systems, especially complicated ones such as bacteria - let alone one in vivo - has been a longstanding goal in experimental QM. To...
  12. jedishrfu

    Medical The Cause of Alzheimer's: Mouth Bacteria ?

  13. Rayanna

    Introduction of antibiotic resistance gene to a bacteria

    Why would anyone like to intoduce a antibiotic gene in a bacteria if it will make it resistant to antibiotics which is not of any advantages to humans?
  14. jim mcnamara

    Gut bacteria in the brain?

    This article discusses some findings. The findings show a possibility: gut bacteria may coexist in the brain tissue of mammals. Humans are mammals. There is room for skepticism in the endeavor so far. Example: contamination of cadaver brain tissue samples. The reason for this position on...
  15. jedishrfu

    B What's next? Quantum Bacteria

    In a recent Scientific American article, researchers have claimed to have quantum entangled some bacteria: https://www.scientificamerican.com/article/schroedingers-bacterium-could-be-a-quantum-biology-milestone/
  16. M

    MHB Approximately how many minutes will it take for the population to grow from 1,000 to 500,000 bacteria?

    The population of a bacteria culture doubles every 2 minutes. Approximately how many minutes will it take for the population to grow from 1,000 to 500,000 bacteria? Can someone set up the proper equation needed? I can then work it out.
  17. B

    What are the major taxonomic orders of homoacetogens?

    Is there a database that can help answer this question? Any references? Thank you!
  18. C

    Identifying Unknown Bacteria

    Homework Statement I have done tests on this unknown bacteria and this were the results: Cocci shape Gram (-) negative Catalase (+) positive (only one bubble though) Oxidase( - )negative Has endospores (used Schaeffer-Fulton method) Antibiogram: Resistant to Streptomycin...
  19. Ygggdrasil

    What type of bacteria evolved into mitochondria?

    An important step in the evolution of plants, animals, and other complex, multicellular forms of life was eukaryogenesis, the evolution of eukaryotes. Eukaryotes are one of the three major classifications of life (alongside single-celled bacteria and archaea) and are characterized by cellular...
  20. mark!

    Medical The role of bacteria in cancer development

    It is known that a high amount of bacterial DNA is often present near cancer cells. There are about 7000 pieces of bacterial DNA in healthy cells, but researchers found 691,000 inserted pieces of bacterial DNA in cancer cells. That’s almost 200 times as much, which implies that there is a...
  21. Spinnor

    Medical What do they "eat" besides our flesh, flesh eating bacteria

    Are all animal groups equally susceptible to the flesh eating bacteria that has been in the news lately (is Google news just trying to freak me out)? Would environmental stresses on animal populations make animals more susceptible to this bacteria and thereby increase the environmental presence...
  22. X

    Help identifing a bacteria

    http://www.scienceforums.net/topic/112257-help-me-identify-a-bacteria/its catalase +, oxidase +, ferments glucose and produces gas from the process, and is a gram + facultative anaerobe and its highly resistant to antibiotics and motile + and has been seen to grow up to temps of 103°F, colonies...
  23. mfb

    Just add poison: Bacteria outperform plants in efficiency

    The authors call them "cyborg bacteria", but as far as I can see they didn't change the bacteria artificially, they just put them in unusual conditions, including poison. They used bacteria that get rid of poisonous substances (such as cadmium) by forming crystals out of them. Under the right...
  24. R

    Medical Can bad bacteria form on the sauerkraut under the brine

    Also does bad bacteria(mold) forms on the weight(i.e use to submerged the cabbage) ,on the portion that is above the brine. I use glass paper weight, as I think they only form on food surface. My thought, sauerkraut is safe, as long it is submerged inside the brine and mold formation is only...
  25. mktsgm

    Bacteria and Phagocytosis

    Normally invading Bacteria are phagocytosed by phagocytes. Phagocytes are specialised cells. But, if a non-phagocyte cells are infected with bacteria how those cells handle this situation? Do they succumb to the bacteria? Or they too Phagocytosis the invader?
  26. L

    Single biggest obstacle to Earth bacteria thriving on Mars

    If we took some of Earth's hardiest extremophile microorganisms and placed them on Mars, what one factor on Mars would be most difficult for them to cope with? too cold, low oxygen, low atmospheric pressure, radiation, lack of liquid water, toxic soil, lack of organic material, acidity Please...
  27. Zeynel

    How do bacteria in sauerkraut stay alive?

    When I make sauerkraut after adding salt I pound the cabbage with a wooden mallet to release its juice. Then I press it hard into the jar. I was wondering how the lactobacillus that ferment the cabbage survive the pounding and pressing. Thanks.
  28. ShayanJ

    Difference between the Bacteria and the Archaea

    I don't know much about biology but the origin of life has always been very interesting to me so I sometimes check to see whether there was any progress or not. Now this recent development seems so important but I don't quite understand it because I don't know the difference between the Bacteria...
  29. N

    B The Chinese have proposed teleportation of a bacteria

    Is there any physical reason why the teleportation of a microorganism would be absolute fantasy ? The wikipedia page for quantum teleportation says nothing bigger than an atom has been teleported. "Here we propose a straightforward method to create quantum superposition states of a living...
  30. karush

    MHB Another bacteria growth problem

    $\tiny{205.22}$ $$\displaystyle b'(t)=8^5-2(8^4)(t) \\ b'(0)=8^5-2(8^4)(0)=8^5=3.3 \cdot 10^4 \, \frac{p}{h} \\ b'(4)=8^5-2(8^4)(4)=0 \,\frac{p}{h} \\ b'(8)=8^5-2(8^4)(8)=-8^5=-3.3 \cdot 10^4 \, \frac{p}{h}$$ $$\text{suggestions?}$$
  31. Spinnor

    Scientists watch as bacteria evolve antibiotic resistance

    From, https://www.sciencenews.org/article/scientists-watch-bacteria-evolve-antibiotic-resistance For bacteria, practice makes perfect: Adjusting to ever higher levels of antibiotics preps them to morph into super resistant strains, and scientists can now watch it happen. A new device — a huge...
  32. Psinter

    Can a cat become infected with a bacteria or virus from rat?

    I once saw a cat in the streets playing with a living mouse. The mouse wasn't moving, but it was breathing. The cat moved it from paw to paw and then took it in its mouth and moved it to another place where it kept playing with it. Can a cat become infected with bacteria or virus for...
  33. Ygggdrasil

    Bacterium with a Minimal Genome

    How many genes does it take to make a living organism? Scientists at the J Craig Venter Institute published a paper today in the journal Science describing the design and synthesis of a bacteria containing the minimal set of genes required for that organism to live. Their work leverages their...
  34. Docscientist

    How does Chemosynthetic bacteria obtain energy?

    We all know ATP is responsible for providing energy.But in case of chemosynthetic bacteria they oxidize various inorganic substances such as nitrates,ammonia and use the released energy for ATP production.shouldn't it be the other way round ? I mean ATP should help in producing energy not the...
  35. Q_Goest

    Ion channels enable electrical communication in bacteria

    Here’s an interesting bit of research regarding how bacteria communicate through ion channels. It talks about biofilms which I understand as being thin films of bacteria that colonize the surface of teeth for example: The bacteria then communicate using what sounds like a 2 dimensional EM wave...
  36. I

    Can DNA from an animal ever end up in bacteria or viruses?

    I was wondering if it is possible for a bacteria to enter a body and somehow get some amount of that animal's DNA in itself if and when it leaves the body? Or if it just continues to live in the body. Basically does DNA ever linger around? I heard about "DNA dropping" in organisms, if that's the...
  37. Stephanus

    Percentage of hydrocarbons in living organism

    Dear PF Forum, I'm interested in how much energy our organic waste contain. I have read this article https://en.wikipedia.org/wiki/Composition_of_the_human_body Elements composition of plants The elements composition of human body (and animal?) and plants resemble. Bacteria has slightly...
  38. patrickbotros

    What's the difference between the capsule and cell wall?

    In bacteria there's a capsule but I'm not sure what it is/does.
  39. Vannay

    Electron Transport in Bacterial Nanowires

    I was reading through a paper about the first case of experimentally proving that electron transfer can occur over the length of a bacterial nanowire. The paper mentioned that, previously, electron transfer was only measured across the thickness of the wire. "Thus far, there has been no...
  40. G

    Bacteria in the human body: when we die and when we are born

    It is said that around 90% of the cells in a human body are symbiotic bacteria living thanks to us. When we die, do most of them also die? Or do they manage to survive without us and find a new 'home human'? And opposite, when and how do we get all those bacteria after conception? Do we get...
  41. B0b-A

    Any evidence bacteria can exist within mitochondria in humans?

    I heard a claim bacteria can exist within human mitochondria, is there any evidence that is true ?. mitochondria"']https://www.google.com/search?q="bacteria+within+mitochondria"[/URL] only gets one hit, and the examples given are not human.
  42. Eagle9

    What toxins do the E.coli bacteria generate at death phase?

    I have heard that bacteria produce some chemicals/toxins when it dies at the death phase. I need to know exactly what chemicals are produced by E.coli when it dies? Ethanol? Peptides? It this problem explored? If so – how these toxins impact on bacteria? :rolleyes:
  43. P

    Bacteria only found in dry areas as cysts?

    Hi! I'm doing a worksheet on Body Size, Heat Loss and SA/Vol Ratio. The question I'm confused by is: "The smallest organisms such as bacteria, protozoa and unicellular algae live in water or a saturated atmosphere. They are only found in dry situations as cysts or spores. Why?" The wording...
  44. Eagle9

    Do the bacteria proliferate during Lag-phase?

    In various sources I found the different opinions about this. Which one is true? http://en.wikipedia.org/wiki/Bacterial_growth They say bacteria do not proliferate during lag-phase. They say bacteria do proliferate during lag-phase. They say bacteria do not proliferate during lag-phase...
  45. E

    Is it possible to be infected by the same cold virus twice?

    I am just getting over a relatively minor headcold, and I was curious if it was possible to get infected by the same bug you just got over. My keyboard, computer desk, and other objects are covered in these germs as I have touched them and sneezed on them countless times in the past 5-6 days...
  46. N

    Can bacteria nitrify ammonia if it is bonded to a base?

    If an ammonium ion is bonded to let's say chlorine for simplicity sake, and NH4Cl is created, can nitrifying bacteria come in and still create nitrites and nitrates from the ammonia if it is bonded to the chlorine? I am asking this because I am planning to make a schematic for an aquaponics...
  47. haael

    How can bacteria synthesize human insulin?

    I have just read that genetically modified e. coli can synthesize human insulin. But I wonder. Human (eucaryotic) genes have all kinds of introns, regulators, starting sequences etc. Bacteria don't have all of those. How can a procaryota produce an eucaryotic peptide? Has the insulin gene been...
  48. mark!

    Dangerous Bacteria: Examples of E. Coli & More

    It is known that some bacteria are dangerous ONLY when they're in the wrong place, f.i. E. Coli. Does anyone know some more examples?
  49. N

    Find the number of bacteria after 12 hours?

    Homework Statement A bacteria culture contains 1100 bacteria initially and doubles every hour.Find the number of bacteria after 12 hours. (This is a numerical answer; you can enter all of the digits or use exponential form with ** instead of ^ for exponentiation.) n(12) ____ = bacteria Homework...
  50. N

    Number of bacteria in a culture

    Homework Statement The number of bacteria in a culture is given by the formula n(t) = 700e0.65t, where t is measured in hours. What is the initial population n0 of the culture (at t = 0)? n0 = Approximately how many bacteria, N, will the culture contain after 5 hours? N = The Attempt at a...