Hi every one,
I have a problem in isolating bacteria capable of degrading sulfamethoxazole (SMX). My inoculum is granular activated carbon collected from lab biological activated carbon filter. The influent of the column is river water (SMX: 14 ng/L). They also spiked 15 micro-pollutants including 2.5 ppm of SMX into the influent around 1 year ago and C amendment (formaldehyde (100 μg/L), glyoxal (30 μg/L), formate (400 μg/L), and acetate (300 μg/L) 1X monthly.
The base medium I used is nitrate mineral salt. I incubated GAC in 3 types of media spiked with 100 ppm of SMX. one contains only base media, others are base media supplemented with the C amendment (10x) or 1/10 dilution of R2A.
My first enrichment worked well, SMX was degraded quickly in the cultures after 7 days. I think SMX also underwent physical absorption on GAC. But for my second enrichment (inoclum/media: 10%), I have tried several times but no significant degradation of SMX happens. I change the condition like decreasing final concentration of SMX to 50 and 10 ppm and decreasing concentration of C amendment (5x), but it still doesn't work. in some of my second enrichment cultures, I could see bacteria grow quickly after 3-4 days, but they did not degrade SMX.
Would you mind giving me some suggestions?
Thank you so much.
Did you try to screen isolates using SMX as the sole carbon source?
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