3.6.2. Percentage of Bacterial Growth Inhibition

The inhibition of bacterial growth was further determined quantitatively based on the OD600 value measurements. The percentage of bacterial growth inhibition of *C. pentandra*/Ag-NPs against the tested bacteria is summarized in Table 3. The percentage of bacterial growth inhibition showed high inhibitory activity against all tested bacteria which supported the results obtained by using antibacterial disk diffusion assay analysis. Surprisingly, the percentage of inhibition of bacterial growth by ampicillin antibiotic standard is lower than that of *C. pentandra*/Ag-NPs. However, there is no significant difference in the percentage of inhibition of bacterial growth between the bacteria species used (*p* > 0.05). The percentage of inhibition of bacterial growth of Gram-positive bacteria (*S. aureus* and *E. faecalis*) is lower than Gram-negative bacteria (*E.coli* and *P. vulgaris*). However, there is no significant difference in the percentage of inhibited bacterial growth between the species used (*p* > 0.05). This might be due to the less structural difference in cell wall compositions between Gram-positive and Gram-negative bacteria [43]. The high percentage of bacterial growth inhibition was observed for *C. pentandra*/Ag-NPs at the highest dosage (4 mg) against all tested bacteria (>90%). Conversely, there is no significant difference with the increasing mass of *C. pentandra*/Ag-NPs used from 1 to 4 mg. This can be explained due to the Ag-NPs deposited on the *C. pentandra* fiber surface are randomly distributed on the *C. pentandra* fiber surface.


**Table 3.** The percentage of bacterial growth inhibition of *C. pentandra*/Ag-NPs against different bacteria species.

NA means no activity; <sup>a</sup> is mean of the triplicate experiment, ±Standard Error (SE).
