If you were subculturing from pure cultures - introduction of contaminants represents failed aseptic technique. What kind of contaminants do you see?

Phil Geis Thanks a lot for your response. as you see, the bacteria have this kind of -contamination.

Looks like Bacillus. Can you Gram stain?

Phil Geis Yes I can Gram stain

what did you see?

Phil Geis After Gram staining, I observed bacteria in the shape of a sphere and a rod with purple and pink colors.

Reads as a mixed cultures. Both target microorganisms should appear as Gram negative (pink) rods.