Hi good evening. Me and my team are actually currently conducting a research on the antibacterial potential of citrus fruits (calamansi, lemon, mandarin) against Pectorbacterium caratovorum to prevent soft rot on tomatoes. So we decided to find the ZOI of our treatments first. We made use of a 20% pure extract which we diluted in 80% water. We have 5 treatments in total, 3 citrus fruits, and one positive and negative control. But the problem is literally no ZOI appeared. Not even on the positive control. What do you think is wrong? We're currently at a loss on what to do next
The lack of a zone of inhibition in a positive control during antimicrobial susceptibility testing can be attributed to several factors as follows;
Resistance Mechanisms,Some bacteria have developed resistance mechanisms that render them unaffected by the antimicrobial agent being tested. For example, a positive control strain might produce enzymes that degrade the antibiotic ( for example beta-lactamaze enzymes that break down beta-lactam antibiotics like penicillin).
Innate Resistance,Certain bacterial species are naturally resistant to the specific antibiotics due to their cell wall structure, efflux pumps, or other intrinsic factors. For instance, Gram-negative bacteria are often resistant to vancomycin, which primarily targets Gram-positive bacteria.
Inadequate Concentration,If the concentration of the antimicrobial agent in the positive control is too low, it may not inhibit bacterial growth. This could occur due to errors in preparation or dilution of the control sample.
- Badges
- Science topic
- Similar topics
- Biological Science
- Botany
- Pharmaceutical Botany
- Plant Extracts