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    Mic531 Lab Report 1

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    Ahmad Nur Aqmal
    This lab report describes culturing and purification techniques used to isolate bacterial colonies from a mixed culture. The techniques included inoculating a sterile broth with the mixed culture and incubating to observe turbidity. A dilution streaking method on nutrient agar was also used, where the mixed culture was streaked across four quadrants to separate bacteria and allow isolated colonies to grow. The student was partially successful, obtaining growth in the first three quadrants but no isolated colonies in the fourth. Possible errors included a lack of aseptic technique and water droplets on the agar plate. In conclusion, the techniques helped observe purification of isolates from a mixed culture, though improvements could be made to obtain fully isolated colonies.

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    © All Rights Reserved
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    Mic531 Lab Report 1

    Uploaded by

    Ahmad Nur Aqmal
    683 views6 pages
    This lab report describes culturing and purification techniques used to isolate bacterial colonies from a mixed culture. The techniques included inoculating a sterile broth with the mixed culture and incubating to observe turbidity. A dilution streaking method on nutrient agar was also used, where the mixed culture was streaked across four quadrants to separate bacteria and allow isolated colonies to grow. The student was partially successful, obtaining growth in the first three quadrants but no isolated colonies in the fourth. Possible errors included a lack of aseptic technique and water droplets on the agar plate. In conclusion, the techniques helped observe purification of isolates from a mixed culture, though improvements could be made to obtain fully isolated colonies.

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    MIC531 LAB REPORT 1

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    This lab report describes culturing and purification techniques used to isolate bacterial colonies from a mixed culture. The techniques included inoculating a sterile broth with the mixed culture and incubating to observe turbidity. A dilution streaking method on nutrient agar was also used, where the mixed culture was streaked across four quadrants to separate bacteria and allow isolated colonies to grow. The student was partially successful, obtaining growth in the first three quadrants but no isolated colonies in the fourth. Possible errors included a lack of aseptic technique and water droplets on the agar plate. In conclusion, the techniques helped observe purification of isolates from a mixed culture, though improvements could be made to obtain fully isolated colonies.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    683 views6 pages

    Mic531 Lab Report 1

    Uploaded by

    Ahmad Nur Aqmal
    This lab report describes culturing and purification techniques used to isolate bacterial colonies from a mixed culture. The techniques included inoculating a sterile broth with the mixed culture and incubating to observe turbidity. A dilution streaking method on nutrient agar was also used, where the mixed culture was streaked across four quadrants to separate bacteria and allow isolated colonies to grow. The student was partially successful, obtaining growth in the first three quadrants but no isolated colonies in the fourth. Possible errors included a lack of aseptic technique and water droplets on the agar plate. In conclusion, the techniques helped observe purification of isolates from a mixed culture, though improvements could be made to obtain fully isolated colonies.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 6

    MIC531

    APPLIED
    MICROBIOLOGY

    Lab Report 1: CULTURING AND PURIFICATION TECHNIQUES

    Subject code: MIC531

    Student’s name: AHMAD NUR AQMAL BIN HAIRI

    Group: AS2443B

    Student’s id: 2019871572

    Lecturer name: DR ROHANA BINTI MAT NOR

    Date of submission: 18/3/2020


    TITLE

    The study of culturing and purification technique.

    INTRODUCTION

    A mix culture consists of two or more microorganisms. Mixed cultures consist of known species
    to the exclusion of all others, or they may be composed of mixtures of unknown species.
    Culturing technique is a method of multiplying the microbial organisms by letting it grow in
    culture medium under controlled laboratory conditions. Culturing technique procedure also
    known as isolation technique which allow the microorganism to obtain isolated colonies by the
    separation of bacterial cells. The isolation colonies can be obtained by using a culturing and
    purification technique for example streaking plate technique to allow the growth of the isolated
    colonies in the surface of the agar.

    METHOD AND MATERIALS

    Materials

    B. Inoculation of the broth culture

    Pure culture broth

    Inoculating loop

    Sterile nutrient broth

    C. Dilution streaking technique

    Mix culture broth

    Nutrient agar plate

    Inoculating loop
    Methods

    A. Plate labelling
    The sterile nutrient agar plate was labeled before the started the culturing the bacteria. The labeled were
    consists of student name or group, date and the treatment of the experiment. The labels were placed at the
    bottom part of the plate and not on the cover part of the plate.

    B. Inoculation of a broth culture


    The sterile nutrient broth was labeled with the source of the culture. The inoculating loop was sterile first
    with the flame of Bunsen burner. The loop was inserted into the mix culture tube by using appropriate
    aseptic technique and then the loopful of broth were removed from the mix culture tube. The loop was
    inserted into the sterile broth tube and gently swirled. The inoculating loop was sterile again after swirled.
    The broth was incubated at 37°C for 24-48 hours. The broth was observed by comparing McFarland
    standard 0.5 and 1.0. The result was recorded.

    C. Dilution streaking technique


    The inoculating loop was sterile first before start the streaking technique. The loop was sterile with
    Bunsen flame. Next, the sterile nutrient agar plate was divided into four quadrants. The quadrant was
    divided by using a marker pen to draw line to separate them. The cap of the mix culture bottle was
    removed and the let the loop cool by touching the upper side of the bottle. The loopful of the mix culture
    broth was taken out and then applies it onto the first quadrant of the nutrient agar plate. The loop was
    sterile again and then streak again from first quadrant to the second quadrant. The loop was sterile and
    streak again on second quadrant to the third quadrant. The loop was sterile and lastly streak the third
    quadrant to the forth quadrant. The inoculating loop was flame sterile after streaking. The plate was
    incubated upside down at 30°C for overnight. The streaked plate was recorded.

    RESULT

    The culturing and purification technique was demonstrated in this experiment. The inoculating technique
    was demonstrated first. Figure 1 shows the result of broth culture of Escherichia coli. The nutrient broth
    becomes cloudy after 24hours of incubation of E.coli.
    Figure 1: The nutrient broth of E.coli and the turbidity of the broth after 24 hours of incubation.

    Next, the dilution streaking technique was demonstrated. Figure 2 shows the result of streaking technique
    from mix culture containing Escherichia coli and Bacillus subtilis. The nutrient agar plate was growth
    after 24 hours incubation.

    Figure 2: The agar plate of mix culture and the growth of colonies after 24 hours incubation.
    DISCUSSION

    In the experiment, student was task to demonstrate the culturing and a purification technique which is
    included the plate labeling, inoculation of broth culture and dilution streaking technique.

    The inoculation of broth culture was demonstrated to observe the growth of the bacteria by comparing the
    turbidity of the broth. Figure 1 shows that the nutrient broth from this experiment turns cloudy. The
    suspension of bacterial cells is compared to the McFarland turbidity standard (0.5 McFarland turbidity
    standards) by holding the suspension and McFarland turbidity standard in front of a light against a white
    background. This shows that there is growth of bacteria which is E. coli after 24 hours of incubation.

    Next, the dilution streaking technique was demonstrated to observe the growth of the isolated colonies on
    nutrient agar plate. Figure 2 shows that the bacteria grows on the first, second and third quadrant except
    the forth quadrant. Student did not managed to get the single colonies at the forth quadrant which is the
    interest part to observe the isolated colonies. In this dilution streaking technique, student may did an error
    during the process which leading them unable to get the isolated colonies. The actual result for the
    dilution streaking is there must be a single white colony on the forth quadrant which it not touching any
    other colonies and it assumed to be a pure culture.

    The errors that student may did in this experiment was student do not performing aseptic technique
    properly. The aseptic technique is critical in order to get the right result which is involving of sterile
    equipment and the technique that required a heat near with a flame of Bunsen burner during streaking on
    the plate. Next, the plate also might have a water droplet before it was incubate for 24 hours. This might
    also disturb the growth of the colonies. Student should ensure that there is no any droplet on the cover of
    plate before start to incubate it.

    CONCLUSION

    In conclusion, the experiment was conducted to understanding the proper way of plate labeling,
    performing the dilution streaking of agar plate skill and to observe the purify isolate from a mix culture
    broth of sample. The experiment was successfully conducted and the inoculation of broth culture is
    isolated.
    REFERENCES

    Elsevier, Acad. Press. (1979). Methods in microbiology. Amsterdam.

    Ream, W. (2013). Molecular microbiology laboratory: a writing-intensive course. Oxford:

    Academic Press.

    Reddy, C. A. (2007). Methods for general and molecular microbiology. Washington: ASM

    Press.

    Tankeshwar, A., Acharya, T., Medeviance, Shane, Rasha, Olufunto, J., & Modupe. (2017, May

    13). Preparation of McFarland Turbidity Standards. Retrieved from

    https://microbeonline.com/preparation-mcfarland-turbidity-standards/

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