Bacteriology 2 [BCTY 201] PDF

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Bacteriology practical report...

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Bacteriology practical report

[BCTY201]

Food Science and technology

SIPHELELE MHLONGO

(21853157)

Bachelor of Applied Science in Food Science and technology Bacteriology 2 [BCTY201] Practical 1&2 Report

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Bacteriology practical report

[BCTY201]

Food Science and technology

Aseptic culture transfer technique Introduction The aim of these experiment is to become familiar with transfer of microorganisms and aseptic technique transfer of culture from one medium by inoculating another medium. Some objectives of experiment are to acquire aseptic technique skills in microbiology field and also protect culture and media from contaminating microbes in the environment. Other objectives can be obtaining of pure culture by isolating microorganisms from mixed culture.(Vlab.amrita; 2011) Microorganisms commonly exist in mixed population within the environment, they are cosmopolite. If we have to study and identify microorganisms, we must have them in form of pure culture. When working with microorganisms like staphylococcus aureus we need to have medium containing nutrients where organisms will grow. Medium is anything in which we grow on microorganisms. Sterile medium is the one that is free for all forma of life. It is normally sterilised by simple heating it on higher temperature- by lightly passing it through flame so that contaminating organisms will be destroyed. To transfer organisms from pure culture to sterile medium we use method called inoculum. This method is done without introducing unwanted contaminats. It also prevent them from getting access to sterile medium. Cleaning the working surface or warm zone when transferring culture of microorganisms to a nutrient agar is a part of aseptic technique. Other methods that are used is to sterilise the loop by heating it through flame until it turns red and allow it to cool before using it. This helps to ensure that unwanted organisms are destroyed (Biocyclopedia;2016) . Methods and material Work surface was prepared by wiping it with biocide disinfectant and ethanol containing 70% alcohol, then the required media was collected and labelled including staphylococcus aureus (E) bacteria. Bunsen burner was lighten and inoculating loop was sterilised by passing it through flame until the length of wire turns red because of flame, and it was allowed to cool. Culture in a test tube was opened by grasping the cap with the little finger of the hand holding inoculating loop. And the neck of the test tube was sterilised by passing it through flame few times. The loop was cooled by either touching inside walls of the test tube. For removal of broth culture of staphylococcus aureus from the test tube, loop was inserted into the culture and a loopfull of inoculum. The mouth of the test tube was flamed again and the cap replaced. The test tube was then placed in a test tube rack and required medium to transfer the inoculum was picked. For broth medium loop was shaken slightly to dislodge the organisms as loop was removed. The excess liquid was removed by touching the inside wall of the test tube. For slant medium- the loop was drawn lightly over the hardned surface in straight or zig-zag line, and the neck of the test tube and loop were sterilised by flame, the cap was replaced and test tube was returned back on the test tube rack. For plate medium or agar plate, a loopfull inoculum was placed on the surface of the agar plate and dragged lightly several times across the surface in a straight line

Page 2 of 3

Bacteriology practical report

[BCTY201]

Food Science and technology

(culture was spread in a 4-way streak method). All cultures were incubated for 24 hours to 48 hours. Results Morphology on agar plate and slant medium Form Elevation Margin Surface Colour Structure

circular convex Undulate smooth yellow Opaque

Shape and arrangement of staphylococcus aureus- they are grape-like clusters, sphere shaped. On broth medium bacteria appeared in for of sediment. Organisms appeared as a deposit at the bottom of the tube. Discussion Aseptic technique is an important fundamental laboratory skill in the microbiology field. Microbiologists normally use aseptic technique in different was like transferring cultures, inoculating media, isolation of pure cultures, and for performing microbiological tests. As culture went to an incubation, bacteria grow in colonies bacteria grow faster than fungi. By correctly applying streaking technique on agar plate single colonies can be easily obtained, we can also use it to separate colonies of mixed culture. Bacterial colonies can be picked and grown in large quantities. From the result it can be noted that staphylococcus aureus when isolated grow in colonies, they are the pure due to their colour and morphology. Picking too much bacteria or culture with a loop may cause problems with obtaining proper dilution. When transferring liquid culture you should pick up about one drop to obtain single colonies. To prove the reliability of the result, the experiment should be repeated and increase the sample space. (UKEssays; 2018) References Biocyclopedia. 2016. Aseptic Technique and Transfer of Microorganisms. Available at: https://biocyclopedia.com/index/biotechnology_methods/microbiology/aseptic_techni que_and_transfer_of_microorganisms.php [Accessed 15 November 2020]. UKEssays. November 2018. An aseptic technique. [online]. Available from: https://www.ukessays.com/essays/biology/a-aseptic-technique.php?vref=1 [Accessed 15 November 2020]. Vlab.amrita.edu.2011. Aseptic Technique and the Transfer of Microorganisms. Available at: http://vlab.amrita.edu/?sub=3&brch=73&sim=212&cnt=1 [Accessed 15 November 2020].

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