I need to obtain axenic cultures of cyanobacteria for an experimental purpose. Currently, I’m maintaining axenic cultures of cyanobacterial species (Microcystis sp., Nostoc sp., Oscillatoria sp., Limnothrix sp., Synechococcus sp. etc.) in BG11 liquid. These cultures were isolated from freshwater samples by repeated subculturing on both BG11 liquid and solid media. However, I was unable to remove bacterial species that are attached to the cyanobacterial species. Therefore, when preparing fresh cultures of these cyanobacteria bacteria also grow in BG11 liquid media and BG11 agar media. Although I have used the antibiotic “Ampicillin” (100 mg/mL), it didn’t work. So, can anyone suggest a method to avoid this bacteria contamination?
For filamentous cyanobacteria, try breaking the filaments into shorter ones by mild probe sonication (make sure that viability of cyanobacterial cells is not lost) and then washing and filtering in membrane filter. This would wash away considerable amount of bacteria. Few more antibiotics can also be tried (by individually performing susceptibility testing for both filamentous and non-filamentous cyanobacteria), and the antibiotics with milder inhibition on cyanobacteria can be chosen. Once choosing few antibiotics, then the culture can be treated with each of the antibiotics serially to get rid of the bacterial contamination.
- Badges
- Science method