• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Culturing Bacteria.

Extracts from this document...

Introduction

Microbiology ~ Practical 1: Culturing Bacteria Chris Grocock 09/02/04 ~ Introduction Bacteria are microscopic organisms, consisting of one prokaryotic cell. They are relatively simple organisms, with no membrane bound organelle, and only one chromosome. They are quite versatile creatures, being able to survive in both solid environments and liquid (broth). When present on/in a nutrient rich medium such as agar gel, bacteria divide, doubling their population in as little as 20 minutes, forming small gatherings of cells known as colonies, often in circular patterns but also can be filamentous, irregular, spindle shaped, etc. It is possible to estimate the number individual bacterial cells on an agar plate using various dilutions of the bacterial liquid sample. In solid colonies, bacterial growth is greatest on the edge of colonies, growth being fairly slow/non existent in the centre. In broth cultures all cells are at the same stage of growth and same speed but it is almost impossible to estimate the number of bacterium in a broth culture. Bacteria live all around us, particularly in the air we breathe, when bacteria in the air come into contact with a growing medium such as agar, which has an ample supply of nutrients, they will colonise the area and reproduce. Leaving nutrient agar plates in the open air is a good way of demonstrating this process, but bacteria growth can also be manipulated by us. ...read more.

Middle

Their ideal temperature for growth is 37 degrees Celsius. When cultured on solid medium, it is known to produce cream white circular colonies. E.Coli bacteria, normally found in human stool, can exist as a non harmful strain or as a harmful strain, most commonly strain 157. Diseases of E.Coli include diarrhoea, which can be treated with anti-biotic, and meningitis. When grown on solid plates, E.Coli produces small yellow circular colonies. (www.grgreen.com, 2004) (www.sciencenet.com.au, 30/01/2004) (Prescott et al, 2002) ~ Method The method used was the same as the method described in the course module guide. The first method of streaking was as below. The second technique is shown below: The only unique thing was the style of streaking used for the last nutrient agar plate. For this plate, the "smiley face" technique was adopted to try and separate out individual colonies for the mixed culture. The method for this highly skilful technique is outlined below; * Using the aseptic technique (described in the introduction section), the inoculating loop was placed approximately one third of the way down the plate, and approximately one third inward, and streaked as indicated on the diagram (below). * This was done again on the opposite side of the plate, giving an "eye effect". * A similar sized streak was placed on the centre of the plate, giving a "nose" effect. ...read more.

Conclusion

The smiley face method adopted for the 3rd agar plate was not particularly effective at separating colonies. While a few creamy white colonies were distinguishable from the solid streaks, in the pattern known as "spots", the previous two methods were far more effective. Both the line and the snake methods were quite effective at separating out the E.Coli and the M.Leteus colonies. I believe the creamy white colonies to be M.Leteus, and I think that the line method is best at isolating this bacteria. I believe the snake method to be best at isolating the yellow colonies which I believe to be E.Coli. The liquid culture for M.Leteus was fairly clear before and after swirling. Before swirling the bacterium colonised the bottom of the glass container. Because of this, and because of a, much larger presence of M.Leteus on the agar, I conclude from this that M.Leteus is best adapted/"likes" solid media for growth rather that liquid media. The E.Coli was cloudy before and after swirling and produced slime which did not disperse after swirling. This seemed grow well in the liquid culture compared to M.Leteus and grew well on the solid agar, suggesting that it may be more versatile than M.Leteus. The soil sampled produced slime which was present before and after swirling. It also produced a surface layer before and after, and was cloudy before and after. I conclude from this that because of all the different things present, e.g. slime, surface layer, cloudiness, that more than one species of bacterium was present. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Living Things in their Environment section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Living Things in their Environment essays

  1. Marked by a teacher

    The effects of disinfectants and antibacterial soap on bacterial growth

    5 star(s)

    If we were merely repeating our experiment, there would still be several necessary changes. We made an error in not filtering the bouillon broth after it cooled and before it was autoclaved, because the broth had residue and chunks of fat floating in it that inhibited our observations of whether

  2. Marked by a teacher

    Escherichia coli and antibiotic resistanceIntroduction:Escherichia coli, short E. coli is an important bacteria that ...

    5 star(s)

    However, each individual within species has exchangeable genetic information but with subtle differences in the genetic information within each individual to allow slightly different interpretations of the genetic information (how wonderful). A result of this difference is the variations between individuals within single specie (as Darwin pointed out also).

  1. Marked by a teacher

    In this experiment, mung bean seedlings and Brine shrimp eggs were used to study ...

    4 star(s)

    Replicates Replicates are important in order to increase the accuracy of the experiment. The experiment on the germination of mung bean seedlings should be repeated at least three times for each temperature in order that the accuracy of the experiment can be increased.

  2. This assignment is about planning and designing practical experiment to carry out an investigation ...

    burner, because it can melt * In the experiment alcohol is used to sterilise the spreader this may flame, so it must be carefully used and put away from the Bunsen burner and lid must be tightly closed when not in use.

  1. Using the streak plate method, compare the effect of two different brands of toothpaste ...

    After the bacteria is covering the whole plate, sterilise a cork borer by flaming it in the Bunsen burner and then use it to make a single hole in the centre of the agar plate containing the liquid e.g. staphylococcus. This hole is where the toothpaste will be added later.

  2. An investigation into the antibiotic effects of penicillin and streptomycin on the bacterium Escherichia ...

    coli is Gram-negative, due to this I believe that it will have very little, if no effect at all on the E. coli. However, the streptomycin is effective against both Gram-positive and Gram-negative bacteria, which is why I predict that the streptomycin will have an affect on the bacteria, by killing off the bacteria in close proximity to the streptomycin.

  1. Micro-organisms,most effective antibiotic to act against the two types of bacterium: E.coli and B.subtilis.

    1 x scissors * Matches * Sellotape * Glass marker pens The antibiotics on the mastring: Amp - Ampicillin Chl - Chloramphenicol Ery - Erythromycin Met - Methicillin Pen - Penicillin Str - Streptomycin Sfz - Sulphafurazole Tet - Tetracycline An antibiotic is a drug that kills or slows the growth of bacteria and other germs.

  2. Introduction to bacteria

    Antibiotics produced by Bacteria: * Tetracycline * Sreptomycin * Cyclohexamide * Neomycin * Cycloserine * Erythromycin * Kanamycin * Lincomycin * Nystatin * Polymyxin B * Bacitracin In many cases the immune system can wipe out a bacterial infection on its own.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work