Aseptic technique for bacterial manipulation Essay

Introduction
Bacterial manipulation requires a fundamental skill called aseptic technique. This technique insures that no contaminating organism has been introduced into the culture materials as well as the handling tools used to transferred a specimen of interest (Alfred Brown & Heidi Smith, 2006). To learn more about the characteristics of microorganisms, a smear in prepared. A good smear will guarantee the observation of the morphology of the cell, the arrangement of the cells, and internal structures (Alfred Brown & Heidi Smith, 2006). In order to observe cells on a prepared smear a simple, differential or negative stain is used. Simple stain allows bacterial cell to be colored. However, a differential stain such as gram staining takes advantage of the properties of bacterial cell structure different dyes are used to determine the existence of two different cell types gram-positive and gram-negative negative staining is useful to determine the morphology and characteristics of a bacterial cell structure (Alfred Brown & Heidi Smith, 2006). The focus of this laboratory session will be learning how to handle live cultures of bacteria using aseptic techniques, smear preparation, and staining methods.
Materials and Methods
During this experiment instructions were provided by Experiment 2 lab workbook (Gibson, 2016) and aseptic techniques were used as described in Exercise 8 of the laboratory manual Alfred Brown & Heidi Smith, 2006.
Negative staining
Bacillus cereus (B. cereus) and Staphylococcus aureus (S. aureus) cultures were provided. A drop of India ink was added to a slide, later a loop full of B. cereus was dispersed into the dye. Following spreading methods shown in exercise 12 of the laboratory manual, another slide was placed on top of the drop and dragged across the slide in order to spread the suspension. The slide was left to air dry and later examined under oil immersion. This procedure was followed for S. aureus as well. Later a sample from between our teeth was taken with a toothpick and spread into a drop of India ink. The same procedure as above was used to examine the sample.
Simple staining
Bacillus cereus and Staphylococcus aureus cultures were provided. Following simple staining protocol described in exercise 11 of the laboratory manual was used on both bacterial samples. First a loop full of a bacterial sample was placed in the center of the slide and air dry. The sample was heat-fixed by passing it through the bunsen burner flame about 3 to 4 times. The smear was covered with methylene blue during one minute and briefly washed with distilled water. The slide was carefully blotted dry and placed under the microscope to record observations.
Gram staining
Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) cultures were provided. Following gram staining protocol described in exercise 14 of the laboratory manual was used on both bacterial samples.
First a loop full of bacteria was placed in the center of the slide and air-dry followed by heat-fixation of the sample. Crystal violet, Gram's Iodine, decolorized, and Safranin were dyes used during the staining procedure.