Hi everyone,

I have some problem with my bacterial isolation process. I have cultivated SMX-degrading bacteria with contaminated activated sludge as an inoculum for a half of year. The biodegradation of SMX has been observed. My liquid media is basal salts mineral medium (BSM) amended with 100 ppm SMX. Please note that one component of BSM is nitrilotriacetic acid, which could be used as additional carbon source.

In my screening step, I picked up some colonies from solid media. My solid media is BSM amended with 150 ppm SMX.

I cultivated some colonies in ammonia mineral salt (AMS) spiked with 100 ppm SMX from the stock solution. One of them (culture A) shows the growth of bacteria after two days. It means the bacteria can use SMX as carbon source. To confirm this, I transferred a portion of culture A to other fresh AMS media spiked with powder SMX (culture B), but after 5 days no growth is observed.

Since HPLC in my lab has some problem, I could not check the biodegradation of SMX now.

I wonder whether the colonies can grow in culture A but not culture B because my SMX stock solution was prepared in methanol. I prepared stock solution 5 months ago and stored at 4 DegC, so I also wonder if the abiotic degradation product of SMX is the one the colony can use as a carbon source but not SMX.

Could you please help me?

Thank you.

Pham