Testing the efficacy of Agrigold for the control of Enterobacteria cloacaea
Mieke Daneel
ARC-Institute for Tropical and Subtropical Crops,
Private Bag X11208, Nelspruit 1200
June 2014
BlueGold Water and Chemicals
Fairland
2195
Aim
Tests were conducted to determine the efficacy of Agrigold in controlling Enterobacteria cloaceae development on petri dishes.
Material and Methods
Two hundred and fifty mℓ solutions, with different concentrations of Agrigold, were prepared in Erlenmeyer flasks using autoclaved water as shown in Table 1. The pH of the solutions was adjusted to about pH 6 using either a HCℓ or NaOH solution. One mℓ of the Enterobacteria bacterial suspension containing ~109 cfu per mℓ, from an Enterobacteria cloaceae culture (BD 662) isolated from onion leaves and obtained from ARC-PPRI, was then added to each flask. Serial dilutions were made from each flask after 30 min, 1 hour and 3 hours and plated on nutrient agar medium. Bacterial colony counts were made after an incubation period of one day. Each dilution was plated three times. The test was repeated three times over time under similar conditions.
Table 1 Treatment numbers, active ingredients and dosages tested.
| Treatment | Solution description | Dosage (mℓ /250 mℓ) |
| 1 | Water | – |
| 2 | 100 ppm Agrigold | 0.025 mℓ |
| 3 | 200 ppm Agrigold | 0.05 mℓ |
| 4 | 400 ppm Agrigold | 0.1 mℓ |
Results
The results of the three tests can be seen in Tables 2-4. After 30 minutes the 100 and 200 ppm Agrigold showed a reduction of viability of 98% and more whereas the reduction of bacterial development for 400 ppm Agrigold was 99%.
After 1 and 3 hours the reduction in viability for 100, 200 and 400 ppm Agrigold was 99% and higher compared to the untreated control.
Table 2 Percentage reduction in viability of E. cloacaea after 30 minutes
| Treatment | Test 1 | Test 2 | Test 3 |
| 100 ppm AG | Not tested | 98.83 | 98.26 |
| 200 ppm AG | Not tested | 99.97 | 98.32 |
| 400 ppm AG | Not tested | 99.97 | 99.06 |
Table 3 Percentage reduction in viability of E. cloacaea after one hour
| Treatment | Test 1 | Test 2 | Test 3 |
| 100 ppm AG | 99.99 | 99.81 | 99.99 |
| 200 ppm AG | 99.99 | 99.99 | 99.98 |
| 400 ppm AG | 99.99 | 99.99 | 99.99 |
Table 4 Percentage reduction in viability of E. cloaceae after three hours
| Treatment | Test 1 | Test 2 | Test 3 |
| 100 ppm AG | 100.00 | 100.00 | 99.99 |
| 200 ppm AG | 100.00 | 100.00 | 100.00 |
| 400 ppm AG | 100.00 | 99.99 | 99.99 |
Conclusion
Agrigold is effective in reducing the viability of Enterobacteria claoceae with 98% or more after 30 minutes contact period.