Hey there Sign in to join this conversationNew here? Join for free

Calculating colony forming units?

Announcements Posted on
    • Thread Starter
    • 0 followers
    Offline

    ReputationRep:
    Hope this is in the right place, if not sorry!
    I'm a bit stuck on what i'm supposed to be doing in this calculation.. If anyone could give me some pointers i'd really appreciate it

    "Soil suspension has been prepared as follows: 10g soil was made up to 15ml with peptone solution. You are provided with a 10^-4 dilution of the original suspension. This was prepared in two steps; 0.1ml of suspension was added to 9.9ml peptone to give 10^-2 dilution. This was repeated to give the 10^-4 dilution.
    Calculate the number of colony forming units (CFUs) per gram of soil in your sample, take careful account of the dilution used for counting in your calculation"

    I prepared 10^-5 10^-6 and 10^-7 dilutions by removing 0.5ml each time to the new dilution.
    I plated 1ml samples of the four dilutions. Then after incubating I counted 300 colonies in the 10^-5 dilution..

    Now i'm stuck on what to do to calculate per ml or g .. I know to multiple the number of colonies by the dilution factor so 300 * 10^5 .. but do I need to do something else to get the answer?
    Thanks!
    • 19 followers
    Offline

    ReputationRep:
    It's been a while since you posted and nobody's replied yet...maybe you should check out MarkedbyTeachers.com, TSR's sister site. It has the largest library of essays in the UK.

    They've got over 181,000+ coursework, essays, homeworks etc.. all written by GCSE, A Level, University and IB students across all topics. You get access either by publishing some of your own work, or paying £4.99 for a month's access. Both ways give you unlimited access to all of the essays.

    All their documents are submitted to Turnitin anti-plagiarism software, so it can't be misused, and the site's used by hundreds of thousands of UK teachers and students.

    What's more, you can take a look around the site and preview the work absolutely free. Click here to find out more...

Reply

Submit reply

Register

Thanks for posting! You just need to create an account in order to submit the post
  1. this can't be left blank
    that username has been taken, please choose another Forgotten your password?

    this is what you'll be called on TSR

  2. this can't be left blank
    this email is already registered. Forgotten your password?

    never shared and never spammed

  3. this can't be left blank

    6 characters or longer with both numbers and letters is safer

  4. this can't be left empty
    your full birthday is required
  1. By joining you agree to our Ts and Cs, privacy policy and site rules

  2. Slide the button to the right to create your account

    Slide to join now Processing…

Updated: October 26, 2011
New on TSR

Rice cooker in your uni halls?

Would you bring a rice cooker to uni?

Article updates
Reputation gems:
You get these gems as you gain rep from other members for making good contributions and giving helpful advice.