Table 2.
Antibacterial activity of PLA-based nano-biocomposite films obtained at 2 incubation times (3 h and 24 h) and 3 different temperatures (4, 24 and 37 °C) against E. coli and S. aureus 8325-4, expressed as cell viability (%).
| Formulation | Cell Viability (%) | |||
|---|---|---|---|---|
| S. Aureus 8325-4 | E. Coli | |||
| 3 h | 24 h | 3 h | 24 h | |
| At 4 °C | ||||
| PLA | 100.0 ± 1.7 a | 100.0 ± 1.8 a | 100.0 ± 6.7 a | 100.0 ± 2.5 a |
| PLA/T | 83.5 ± 3.3 b | 85.5 ± 1.1 c | 65.4 ± 5.4 b | 60.6 ± 1.0 c |
| PLA/D43B2.5 | 98.0 ± 1.1 a | 88.6 ± 0.9 b,c | 83.5 ± 2.9 a | 74.0 ± 4.2 b |
| PLA/D43B5 | 91.1 ± 1.3 c | 94.4 ± 1.7 a,b | 88.0 ± 3.2 a | 77.8 ± 3.5 b |
| PLA/T/D43B2.5 | 68.0 ± 0.3 d | 60.9 ± 2.0 d | 53.7 ± 3.3 b | 52.0 ± 0.5 c,d |
| PLA//T/D43B5 | 70.0 ± 0.5 d | 61.6 ± 1.0 d | 54.4 ± 2.9 b | 50.0 ± 0.7 d |
| At 24 °C | ||||
| PLA | 100.0 ± 1.0 a | 100.0 ± 0.5 a | 100.0 ± 3.8 a | 100.0 ± 2.2 a |
| PLA/T | 72.8 ± 2.2 b | 62.4 ± 1.5 b | 69.5 ± 1.6 b | 66.2 ± 1.4 c |
| PLA/D43B2.5 | 83.4 ± 1.1 a | 83.4 ± 1.4 c | 75.3 ± 2.8 b | 82.6 ± 1.9 b |
| PLA/D43B5 | 75.4 ± 1.4 c | 81.2 ± 1.7 c | 70.3 ± 1.3 b | 80.0 ± 3.3 b |
| PLA/T/D43B2.5 | 56.1 ± 1.2 d | 59.4 ± 1.4 b | 53.1 ± 0.2 c | 57.9 ± 0.7 c,d |
| PLA//T/D43B5 | 56.6 ± 2.0 d | 58.7 ± 0.8 b | 59.6 ± 2.0 c | 60.2 ± 1.5 d |
| At 37 °C | ||||
| PLA | 100.0 ± 3.8 a | 100.0 ± 2.1 a | 100.0 ± 1.7 a | 100.0 ± 3.1 a |
| PLA/T | 57.9 ± 2.2 b | 73.3 ± 1.2 c | 62.9 ± 0.5 b | 71.2 ± 1.4 c |
| PLA/D43B2.5 | 63.8 ± 2.0 b | 84.6 ± 0.9 b | 67.6 ± 0.9 b | 79.4 ± 1.2 b |
| PLA/D43B5 | 64.3 ± 1.5 b | 89.8 ± 2.0 b | 64.8 ± 2.3 b | 71.7 ± 1.2 c |
| PLA/T/D43B2.5 | 44.3 ± 1.4 c | 51.6 ± 0.5 d | 47.2 ± 1.2 c | 49.3 ± 0.5 d |
| PLA/T/D43B5 | 48.5 ± 1.1 c | 59.6 ± 3.2 e | 47.3 ± 1.4 c | 53.2 ± 1.2 d |
Data are expressed as cell viability (%), which corresponds to the percentage of the CFU of bacteria growth in nano-biocomposite films compared to that obtained in PLA (set as 100%). Results are expressed as mean ± standard deviation, n = 3. Different superscripts (a, b, c, d, and e) within the same column at a specific temperature indicate statistically significant different values compared at 3 and 24 h for S. aureus 8325-4 and E. coli at different temperatures.