Ubiqutous Nature of Microorganisms Essay

535 WordsFeb 26, 20153 Pages
INTRODUCTION Bacteria are unicellular microorganisms that are typically a few micrometres in length. They constitute a large domain of prokaryotic organisms which are organisms that have a genetic material or DNA not enclosed in a cellular compartment called nucleus. Bacteria come in different shapes including rod shaped (bacilli), others are shaped like little balls and are called cocci and others are helical or spiral in shape. Bacteria reproduce by binary fission. Bacteria grow everywhere including our hands, mouth and soil. It can also be grown in laboratories using different techniques including spread plate whereby a small volume of dilute bacterial mixture is transferred to the centre of an agar plate and is spread evenly over the surface with a sterile, L-shaped glass rod. The other technique used is pour plate technique whereby you separate one species of bacteria from another by diluting one loopful of organisms into three liquefied agar plates with the hope that one of the plates poured will provide an ideal sample for isolation. The other technique is plate count agar or standard method agar which is a microbiological growth medium commonly used to assess or to monitor total or viable bacterial growth of a sample. Plate count agar is not a selective medium therefor can grow any bacteria. The aim of this experiment is to estimate the size of microbial population grown on different media. MATERIALS AND METHODS During the experiment, mouth was swabbed with sterile cotton tipped applicator stick. The cotton tip was then rubbed gently in a nutrient agar. Fingers were also rubbed into surface of mannitol salt agar covering every part of the surface of the agar. The two agar plates were then incubated for 48 hours at a temperature of 35-37 degrees Celsius. In the plat count technique 1mg of soil was dispersed in a 99ml diluent giving dilution of 1:100, 1

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