16
CHAPTER 4 PRESENTATION, ANALYSIS AND INTERPRETATION OF DATA
This chapter presents, analyzes and interprets the data gathered from the experiment conducted on the antibacterial property of the leaf extract of A. carambola (Starfruit) as set in the earlier part of this study.
Significant Findings Table 1 presented the data for the growth of the microorganisms using the different treatments. Table 1. Mean Zone of Inhibition (mm) of Averrhoa carambola leaf extract for 24 hours of incubation 24 hours of incubation Treatments
B. subtilis
E. coli
T1 (DH2O)
0
0
T2 (Amoxicillin)
13.47
28.8
14.67
10.8
81.24**
618.55**
T3 (leaf extract of A. carambola (Star Fruit)) Computed F-value (Tabular F-value= 10.93) Legend: ** - significant difference at 1% ns - not significant
The table showed the results for the mean zone of inhibition of the bacteria in millimeter for the 24 hours of incubation. T 1, which is the negative control for B. subtilis, showed 0mm meaning, there was no inhibition that
17
occurred; the T2 or positive control, showed the mean zone of 13.47mm; and T 3, which is the leaf extract of A. carambola (Starfruit), showed a mean zone of 14.67mm after 24 hours of incubation. The data revealed that there was an inhibition in the growth of the gram-positive B. subtilis in both of the treatments but treatment 3 has greater mean zone of inhibition than treatment 2. This means that the extract was effective in inhibiting the growth of the bacteria. The computed F-value for the 24 hour incubation of B. subtilis was 81.24 which was greater than the tabular value of F-test which was 10.93, significant at 1% level of significance. The result showed that there was a significant difference in the zone of inhibition in B. subtilis using different treatments, therefore, rejecting the null hypothesis. On the other hand, for the gram-negative E. coli, the result showed that there is a mean zone for T2 which is 28.8mm; and T3 having the result of 10.8mm for 24 hours of incubation. This implies that there was an inhibition in the growth of the gram-negative E. coli in both of the treatments but T3 has lesser mean zone of inhibition than T 2, meaning that there was a little effect in inhibiting the growth of the bacteria for the A. carambola (Starfruit) leaf extract. The computed F-value for the 24 hour incubation of E. coli was 618.55 which was greater than the tabular value of F-test which was 10.93, significant at 1% level of significance. The result showed that there was a significant difference in the zone of inhibition in E. coli using different treatments, therefore, rejecting the null hypothesis.
18
Table 2. Mean Zone of Inhibition (mm) of Averrhoa carambola for 48 hours of incubation 48 hours of incubation Treatments
B. subtilis
E. coli
T1 (DH2O)
0
0
T2 (Amoxicillin)
13.8
29.67
14.5
9.97
69.53**
1523.25**
T3 (leaf extract of A. carambola (Star Fruit)) Computed F-value (Tabular F-value= 10.93) Legend: ** - significant difference at 1% ns - not significant
The data in table 2, showed the result for the mean zone of inhibition of bacteria in millimeters after 48 hours of incubation. For gram-positive B. subtilis and gram negative E.coli, the negative control (T1), showed 0mm, meaning that there was no inhibition that happened. For the positive control (T 2) and the experimental treatment (T3), the results exhibited an inhibition with a mean zone of 13.8mm and 14.5mm respectively. This implies that both of the treatments was effective in inhibiting the growth of the bacteria, indicating that the mean zone of the treatment 2 is greater than the treatment 3. The computed F-value for the 48 hour incubation of B. subtilis was 69.53 which was greater than the tabular value of F-test which was 10.93, significant at 1% level of significance. The result showed that there was a significant difference in the zone of inhibition in B. subtilis using different treatments, therefore, rejecting the null hypothesis.
19
For the gram-negative E. coli, the result showed that there is a mean zone for T2 which was 29.67mm; and T3 having the result of 9.97mm for 48 hours of incubation. This indicates that there was an inhibition in the growth of the gramnegative E. coli in both of the treatments but T3 has lesser mean zone of inhibition than T2, meaning that there was a mild effect in inhibiting the growth of the bacteria for the A. carambola (Starfruit) leaf extract. After 48 hours of incubation, the computed F-value of E. coli was 1523.25, which was higher than the tabular value, 10.93 that is significant at 1% level of significance. The null hypothesis was rejected because it was shown that there was a significant difference in the zone of inhibition in E. coli using the different treatments. With the results of the conducted experiment, the researchers observed that after 48 hours of incubation, the measurement of of B. subtilis’ zone of inhibition in T2 and T3 decreased. As for the E. coli’s zone of inhibition, the measurement of T2 increased but was decreased in T3. In both tables of mean zone inhibition for 24 and 48 hours, treatment 2 which is the positive control of B. subtilis having a result of 13.47 and 13.8 respectively, is greater than treatment 3 which is the experimental control with 14.67 and14.5 respectively. It is expected that the results of treatment 2 is higher than treatment 3. One of the possible reasons why is due to the inconsistent inoculation of the bacterial broth in the plates. There was a study conducted by Das, B.N., and Ahmed, M. in 2012, regarding the antibacterial activity of A. carambola (Starfruit) methanolic fruit
20
extract. The researchers used disk diffusion method to evaluate the antibacterial activity of A. carambola (Starfruit), and it was shown that the methanolic extract in water soluble fraction of the A. carambola performed significant antibacterial activity against some gram-positive bacteria; Staphylococcus aureus with a mean zone of 23mm, Bacillus subtilis with 10mm, and Bacillus cereus with a mean of 21mm. Also in some gram-negative bacteria; Escherichia coli with a mean zone of 10mm,
Salmonella paratyphi with 11mm, and Shigella
dysenteriae with 13mm. Also, according to the study of Das. J., et al, in 2013, they used the bark of A. carambola ethanol extract to investigate its antibacterial, cytotoxic and phytochemical properties. The phytochemical screening tests confirmed that flavonoid, glycoside, alkaloid, carbohydrates, saponin and steroid were present in the bark extract. For antibacterial properties, it indicates that the ethanol extract of A. carambola bark was able to control some of the bacteria and it showed that the plant extract has a zone of inhibition against Salmonella typhi, Pseudomonas aeruginosa, Escherichia. coli and Bacillus megaterium, with mean zones that ranges from 27mm to 32mm. On the other hand, the bark extract didn’t
showed
good
performance
against,
which
are
Vibrio
cholera,
Staphylococcus aureus, Shigella sonnei, Bacillus subtilis, Bacillus cereus and Shigella dysenteriae with mean zones that ranges 17 to 26mm. Both of the study mentioned above, implies that the extracts of the different parts of the plant material A. carambola (Starfruit) specifically the bark and the fruit, has antimicrobial efficiency that can inhibit the growth of certain
21
bacteria of gram-positive and gram-negative and also fungi. Same results obtained from the current experiment that the leaf extract of A. carambola (Starfruit) has the capacity of antibacterial activity specifically from the bacteria B. subtilis and E. coli thus, the leaf extract of A. carambola has the possible mechanism of action in inhibiting the growth of bacteria.