Curing of Mammalian Cell Lines from Severe Bacterial Contamination: A Descriptive Approach

Abstract

Mammalian cell culture has been shown to be critical in the study of human cellular physiological processes. However, microbial contamination remains a common and serious issue for researchers globally, and it unfortunately persists even when various aseptic measures are meticulously followed. This can have serious implications, such as spurious, non-reproducible data resulting in tainted results and the loss of vital biological samples.  The most common causative agent contaminating mammalian cell lines are mycoplasma. In this article, we report the identification and eradication of bacterial contamination encountered during mammalian cell line culture. We have been on the brink of losing the cell lines due to the contamination. The contaminant was recognised as gram-positive bacteria from the genus Bacillus that's already resistant to penicillin and streptomycin using 16S rDNA sequencing. To comprise and finally eliminate the bacterial contaminants, the cultures were handled for two weeks with such a cocktail of antibiotics ciprofloxacin and gentamicin in varying doses to determine the effective curing dose with the least cytotoxicity. Ultimately, the cells were free of bacterial contamination. Consequently, cell lines maintained even in the absence of additional antibiotic pressure remained healthy and normal for an extended period of time (under the microscope). Finally, we revealed that these cells maintained their normal cell cycle properties using FACS.