For the past two months, I have been struggling to get rid of this contaminant. I have tried using Gentamycin (50 µM/mL) and amphotericin B (2.5 µg/mL) in addition to penicillin and streptomycin, which I usually use, but with no effect. I have started cultures with cell stocks of different passages, but observed the same result. I have carried out hydrogen peroxide decontamination of the incubator twice, thoroughly cleaned my working space, and the biosafety cabinet. Tried using a new media bottle. However, the contamination persists. A blank flask with just the complete growth media, grown alongside the cell culture, does not show any signs of microbial growth. The foreign species seems to rupture the PC-12 cell wall. I would highly appreciate your insights.