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Is curd harmful?

  1. Mar 23, 2016 #1
    Heterotrophic bacteria converts milk into curd.So it means it should be present in the curd.Isn't it harmful for our health when we consume it ?
     
  2. jcsd
  3. Mar 23, 2016 #2

    DrDu

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    There are many strains of bacteria populating your gut and they are immensely important to your well being. One even speaks of the bacteriome of a person as the sum of bacteria living inside it. This is a hot spot of research these days and each day new illnesses are liked to changes in the bacteriome. The bacteria used in the production of curd, yoghurt etc. are all ubiquitous in our intestines and certainly not harmful.
     
  4. Mar 23, 2016 #3
    Is there any machine available in the market that can let us see bacteria and virus present in the surrounding ?
     
  5. Mar 23, 2016 #4

    DrDu

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    An electron microscope.
     
  6. Mar 23, 2016 #5

    jim mcnamara

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    To see what is in curd, and grows there: sample the curd throughout the "culturing" phase and try to grow out as many species as possible. This uses culturing medium on petri dishes, and a growth chamber. A modern way which involves expensive lab equipment is to analyze DNA from the curd over a period of time. Why over time? Because the species of beasties growing in the curd change over time as the growth environment changes. For example, curd becomes more acidic as it develops. At some point the bacteria doing the acidfying lose efficiency because they have altered the environment a lot. Other bacteria that like a more aicd environment may kick into high gear.

    FWIW: a lot of cheeses are made from curds created using enzymes - like rennet. So largely the bacteria in that curd came from milk. If the milk was pasteurized beforehand then the bacterial count will be quite low. Commercial production of cheeses often relies on the addition of proprietrary varieties of bacteria and fungi to the curd, prior to curing.

    More FWIW:
    A respectable number of species of microbes are known by their their DNA only, example: methanogenic bacteria.
    As @DrDu pointed out - not all bacteria in food are bad, rather, many are beneficial.
     
  7. Mar 23, 2016 #6

    Ygggdrasil

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    Here's a simple experiment to look at the microbes present on a healthy 8-year-old boy's hand : http://www.businessinsider.com/microbeworld-handprint-bacteria-photo-by-tasha-sturm-2015-6
    microbe.jpg

    In order to determine what bacteria are present in our bodies and in our surroundings, scientists use DNA sequencing on samples taken from these environments then match the sequences they obtain to databases in order to identify the bacterial species present. These studies have enabled us to define the "microbiomes" around and within us. Work in this area is trying to correlate the presence or absence of bacteria with specific health outcomes (e.g. obesity) and determine whether specific changes to the microbiome could impact human health.

    Scientists have also looked at the microbiomes in cheese and published some papers on the topic:
    Paper: http://www.sciencedirect.com/science/article/pii/S0092867414007454
    Popular press summary: http://www.wired.com/2014/07/cheese-rind-microbes/
     
  8. Mar 24, 2016 #7
    I can't carry microscope everywhere.It needs to be something handy.
     
  9. Mar 24, 2016 #8

    Drakkith

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    There isn't anything you can carry around that will let you see viruses. They are simply too small. You can see various bacteria with an optical microscope, but that's not exactly going to fit in your back pocket either.
     
  10. Mar 24, 2016 #9
    One will be invented decades later.:wink:
     
  11. Mar 24, 2016 #10

    Ygggdrasil

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    There are now portable DNA sequencing devices that can be taken out into the field to help monitor viruses (for example, they were used during the recent Ebola outbreak):
    https://www.theguardian.com/science...ile-lab-gives-real-time-dna-data-on-outbreaks
    http://www.nature.com/nature/journal/v530/n7589/full/nature16996.html

    DNA sequencing doesn't allow you to see the viruses, but you can certainly detect them more easily than with a microscope and you get a lot more information (e.g. you wouldn't be able to determine the whether the virus resistant to a particular drug by looking at them in a microscope).
     
    Last edited by a moderator: May 7, 2017
  12. Mar 24, 2016 #11
    How does DNA sequencing lets you detect such things ?
    DNA sequencing is all about modifying the DNA sequence in such a way so that you can even change few of your traits,right ?
     
  13. Mar 24, 2016 #12

    Ygggdrasil

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    DNA sequencing is about reading the DNA sequence, not modifying it. Because different organisms have different DNA sequences (and because we know the sequences of many different bacterial species), if you get a collection of DNA sequences you can identify the organisms they came from. You can also detect specific genes, for example, particular genes or mutations associated with drug resistance.
     
  14. Mar 25, 2016 #13
    I still don't get how DNA sequencing helps in "detecting" microbes present around us.Do we have a kind of device that lets us view the genes of microbes present around us?
     
  15. Mar 25, 2016 #14

    Ygggdrasil

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    Yes. The concept is similar to (but more advanced than) forensic DNA detection that police use. One can sample an environment for cells of any type (human, bacterial, fungal, etc), extract the DNA from these cells, then prepare the sample for DNA sequencing (this involves adding "adaptor" sequences to the ends of the DNA so that it can be read by the sequencing machine). The samples are then applied to the sequencing machine. The machine first amplifies the DNA (makes many copies of the DNA) so that you can get a good signal-to-noise ratio in the measurements. These are able to read the DNA sequence by watching the different bases get incorporated as a DNA polymerase enzyme copies the DNA; each base is labeled with a different color of fluorescent dye, so incorporation of each base produces a flash of light of a different color. By adding bases one at a time and looking at the colors produced, you can read out the sequence of the bases in the copy of the DNA molecule (e.g. you can see the sequence ATTAGCCATGCA... etc.). The resulting sequences can then be fed into databases that can identify which organism the DNA came from and tell you more about what kind of biochemical activity that particular DNA sequence encodes.

    Here's a nice video explaining modern DNA sequencing technology (skip to 1:29 to get to the actual sequencing step):
     
    Last edited: Mar 25, 2016
  16. Mar 25, 2016 #15
    But the problem is I need to get the cells of microbes for which I would need an electron microscope.That's a pretty long process.
    But if there were a pair of spectacles or even contact lens that can show the presence of microbes in our food,devices which we use or in some body else's hands(so that we can keep away from that person),that would be very convenient.Moreover we get to see a lot of diseases nowadays spreading among the people mainly because people have no idea how this thing spreads.They would naturally want to see these dreadful "microbes" with their very own eyes so that they take appropriate steps to keep away from it every time they get to detect it through their glasses.
    I think that is a good way to prevent epidemics in poor and developing countries.But the problem is even if such a device is invented,we would still have to make it more accessible so that every individual gets to use it.
     
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