Meet the Microbes!! Hina´s magical mystery Microbiology lab!

Meet the Microbes!!

Hina´s magical mystery Microbiology lab!

As you watch the film clip....

Ask yourself the following questions...

a) What THREE words come to mind when you first see the flat

b) Why do you think James´s flat makes you feel the way you do?

c) What health risks are posed by keeping the flat in this condition?

Now look at these pictures...

In groups list 5 differences between them!

Microbes are everywhere!

What is microbiology?

• Discuss the word with the person next to you!

• A little introduction!

• So what are we doing this session?a)learning ASEPTIC techniqueb)learning how to CULTURE bacteriac) understanding how to classify bacteria

Working with micro-organismsTo produce useful products, uncontaminated cultures of microbes are required.

This requires certain precautions and sterile techniques to be used.

autoclave

Before we begin!

Using micro-organisms

carbohydrates (energy source)

mineral ions

sometimes +protein, vitamins

Micro-organisms can be grown by man. They need certain nutrients which are often contained in an agar medium:

This is poured into a petri dish.

ContaminationIs when unwanted, possibly harmful microbes grow. You don’t want this to happen.

Aberdeen University

Microbiological techniquesLab coat to protect clothing

Hands washed before & after, gloves worn

Microbes not carried out

Microbes not carried out

1

2

Smooth, non-absorbent work surface (plastic) cleaned with disinfectant before & after

Microbes killed

3

Sterile petri dishes of nutrient agar ready

Less chance of unwanted microbes

getting in (contamination)

5 4 Autoclave / pressure cooker to sterilise glassware (>120oC, 20min) Microbes killed

Techniques (continued)6 Wire loop &

bottles flamed before use

Microbes killed

7 Lid held over petri dish during inoculation

Less chance of unwanted microbes getting in

Prevents microbes getting out.

Microbes killed

8 Inoculated dish sealed with tape

Prevents microbes getting in or out

9 Bin lined with plastic bag for safe disposal of used materials by autoclaving

Now it´s your turn!1. Find a partner

2. Decide what aspects of bacterial culture you are going to investigatee.g. The difference between soap and disinfectant

Effectiveness of handwashing?Bacteria from different parts of your bodyEffect of chemicals on bacterial growthAnything else you can think of!

3. Prepare your work surface and agar plate

4. Innoculate!

5. Seal your petri dish and don´t forget to label it with your names and the date

6. Re-sterilise your work surface

7. Wash your hands!

Classification is the grouping together of things on the basis of features they have in common.

• In 1996 scientists found the reasons for the reclassification of living organisms into three domains.

• Large collaboration of scientists deciphered the full DNA sequence of every gene of bacteria called Methanococcus jannaschii.

• This archaebacterium lives at 85oC, a temperature lethal for regular bacteria as well as multicellular plants and animals.

• Only 44% of this archaebacterium genes resemble those in eubacteria or eukaryotes.

Differences between organisms of three domains:

• Histones – proteins associated with the three dimensional structure of chromosomal DNA, present only in eukaryotic cells.

• Introns – segments of non-coding DNA within genes that are removed before translation

• Size of ribosomes – bacterial ribosomes (70S) – smaller than eukaryotic ones (80S).

• Structure of cell walls

• Structures of cell membranes

Classification of Bacteria

• Archaebacteria: extremists• Eubacteria:

–Heterotrophs–Photosynthetic autotrophs–Chemosynthetic autotrophs

ArchaeaArchaebacteria (archaios – ancient, bakterion – rod) live in

extreme environments where few other organisms survive.They are believed to have been the first forms of life on Earth.

•Methanogenic archaebacteria – inhabit anaerobic habitats and give off methane as a product of their metabolism. They live in the guts of cattle and are responsible for the intestinal gases that cattle produce.

•Halophilic archaebacteria – live only in very salty conditions such as salt flats, where heat from the Sun has evaporated sea water.

•Thermoacidophilic archaebacteria – live in hot acidic springs where temperatures may exceed 100oC and the pH may be as low as 2.

We identify them by:• Investigating their growth requirements• Looking at their size and shape• Studying their reactions to specific stains (such as Gram stain)

Eubacteria

•Eubacteria (eu –good, true, bakterion – rod) make up the remaining bacteria. •They are found in all but the most extreme environments, in soils, sediments, floating free in air or water, in and on the other organisms. •They occur mainly as single cells but also group together in chains or clusters.

To summarise:

• What is meant by the five kingdom classification system?

• What evidence is there that archaebacteria were the first forms of life on Earth?

• What are the main differences between archaebacteria and eubacteria?