Purple Bacilli Research Paper

Results

Observing under 1000X magnification, the gram stain depicts purple bacilli, as seen in Figure 1. Figure 2 depicts growth of a light brown, opaque bacteria on a Phenylethyl Alcohol Agar (PEA) plate. As seen in Figure 3, the blood agar plate shows brown growth surrounded by a very thin clear area. Figure 4 shows an endospore stain of the gram-positive unknown. It depicts green endospores surrounded by pink bacilli. Figure 5 depicts a slant of gram-positive isolate, which appears as an opaque, white film. As seen in Figure 6, the catalase test resulted in vigorous bubbling. The lactose test resulted in a color change from pink to yellow, as seen in Figure 7.

Discussion

The gram stain of the unknown microbe showed purple bacilli, confirming the gram-reaction as positive. This is due to the cellular structure of the cell wall, in which the thick layer of peptidoglycan holds crystal violet dye during the staining process and is not decolorized (K. Rudolph. [Clemson University, Clemson, SC], personal communication). The gram-reaction was further confirmed by growth on the Phenylethyl alcohol agar (PEA)

According to the gram-positive table, the unknown gram-positive microbe is Bacillus subtilis (4). Comparing these results with known biochemical characteristics of B. subtilis, all results are consistent except for the lactose test. B. subtilis is not a lactose fermenter (5). This error could be due to contamination or incorrect incubation time.

B. subtilis is commonly found in soil, but can also be found on human skin and in the gastrointestinal tract. It is commonly used in laboratory research since it’s easily manipulated. While most known for being a widely used antibiotic, it can also be used to convert explosives into safe compounds, help degrade radioactive waste, and is an ingredient in some cleaning agents