A candle and a spirit lamp were lit and placed on each side of the setup to prevent microorganisms from spreading. The petri dish was divided into five segments and labeled as Sample 1, Sample 2, Sample 3, + Control (chloramphenicol), and – Control (distilled water). The vial containing the salt solutions was heated over the flame several times before being opened. This was done to eliminate any microorganisms that might contaminate the area. A swab was dipped into the vial, ensuring it was completely wet. The petri dish was then swabbed using the wet swab while holding it close to the flame. After this, the petri dish was closed, heated several times, and the swab was disposed off. Using forceps, three pieces of filter paper were taken and placed on the petri dish where Sample 1 (strawberry), Sample 2 (citrus lemon), and Sample 3 (green apple) were designated, with one piece on the – Control segment. The forceps were flamed before being reused. A drop of chloramphenicol was placed on the + Control segment, and one drop of deionized water was placed on the – Control filter paper. Next, a micropipette was used to suck in small amounts of the samples (strawberry, citrus lemon, and green apple) and these were placed on the corresponding filter papers according to the labeled samples, while holding the petri dish close to the flame. The petri dish was then closed and sealed with parafilm tape. The initial time was recorded, and the setup was left for 24 hours. After 24 hours, 48 hours and 72 hours, the zone of inhibition on each segment was noted, and as shown in the results table.

note: use the procedures to write Hypothesis
o
Null and Alternate hypothesis
2

1 answer

Based on the experimental setup and procedures you've described, you would formulate your hypotheses to investigate the antimicrobial effect of different fruit extracts (from strawberry, citrus lemon, and green apple) against microorganisms, with chloramphenicol serving as a positive control and distilled water as a negative control.

Hypothesis

Null Hypothesis (H0): There is no significant difference in the zone of inhibition caused by the fruit extracts (strawberry, citrus lemon, green apple) when compared to the positive control (chloramphenicol). The extracts will show no antimicrobial activity against the microorganisms present in the agar.

Alternate Hypothesis (H1): At least one of the fruit extracts (strawberry, citrus lemon, or green apple) will demonstrate a significant zone of inhibition against the microorganisms, indicating antimicrobial activity, with some extracts potentially showing more activity than the positive control (chloramphenicol) and the negative control (distilled water) exhibiting no inhibition.

These hypotheses can then be tested statistically by measuring the zones of inhibition after the incubation period and comparing these measurements across the different segments of the petri dish.