Understanding antibiotic resistance
Understanding antibiotic resistance

This free course is available to start right now. Review the full course description and key learning outcomes and create an account and enrol if you want a free statement of participation.

Free course

Understanding antibiotic resistance

7.1 Back to the soil

Recent technological advances and innovations have allowed a much wider range of microbes to be cultured and novel species and new metabolites to be identified. For example, Activity 7 reveals how teixobactin was discovered in 2015 by a team of scientists in the USA who managed to isolate and culture a previously unidentified soil bacterium. Teixobactin is a new class of antibiotic which is active against Gram-negative but not Gram-positive bacteria (Ling et al., 2015).

Activity 7 Discovering teixobactin

Allow about 15 minutes

First, listen to the interview with Dr Kim Lewis, leader of the research team who discovered teixobactin.

Download this audio clip.Audio player: Audio 2
Skip transcript: Audio 2 Discovery of teixobactin.

Transcript: Audio 2 Discovery of teixobactin.

SCIENTIST
This is a very old problem in microbiology on cultured microorganisms. It's more than 100 years old. And people have tried to replicate the natural environment in the laboratory, and that actually didn't work very well. So we decided to do the exact opposite and simply grow them in their natural environment. And so the way we do that is we have a simple gadget, which we call a diffusion chamber. So we take a sample from soil, for example, dilute it, mix it up with agar, and instead of pouring it in a Petri dish, we sandwiched it between two semi-permeable membranes. And then this contraption, which we call diffusion chamber, that goes back into the soil where we took bacteria from. And so essentially, what that does, that tricks bacteria. Now, they don't know that something happened to them. Everything diffuses through that chamber. They get all the nutrients or growth factors from soil. And once they grow into colonies, then what we found is that with a high probability, they will then grow in a Petri dish. And now you can screen these organisms for their ability to make antibiotics.
We've been collaborating with NovoBiotic, a startup company that does a fairly massive screening using our methods. And one of their typical sources for soil is the backyard of Lucy Ling, VP of biology. And she lives in Lexington, Massachusetts. We got a very large number of anti-microbial compounds, about 30% of soil bacteria will make anti-microbials. And so the next important step is to try to figure out which are the ones that are potentially interesting and useful. And so this new compound, teixobactin, came out of that effort.
End transcript: Audio 2 Discovery of teixobactin.
Copy this transcript to the clipboard
Print this transcript
Audio 2 Discovery of teixobactin.
Interactive feature not available in single page view (see it in standard view).

Now put the steps below in the correct order to match the culturing technique described by Dr Lewis.

Using the following two lists, match each numbered item with the correct letter.

  1. Collect soil sample

  2. Mix diluted soil sample with agar

  3. Sandwich sample between semi-permeable membranes

  4. Place diffusion chamber in soil

  5. Remove diffusion chamber from soil

  6. Select colonies and grow in a Petri dish

  7. Screen for ability to make antibiotics

  8. Assess compounds for efficacy and usefulness

  • a.Fifth

  • b.Fourth

  • c.Eighth

  • d.First

  • e.Second

  • f.Seventh

  • g.Sixth

  • h.Third

The correct answers are:
  • 1 = d
  • 2 = e
  • 3 = h
  • 4 = b
  • 5 = a
  • 6 = g
  • 7 = f
  • 8 = c

What are the advantages of this new technique?

Answer

It re-creates the normal growing conditions of the bacteria, allowing them to be successfully cultivated. The recovery rate by this method is 50% compared with only 1% of cells from soil samples cultured on a Petri dish (Ling et al., 2015).

UAR_1

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has nearly 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to university level study, find out more about the types of qualifications we offer, including our entry level Access courses and Certificates.

Not ready for University study then browse over 900 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus