Answer to Question #64888 in Microbiology for Sophie Wilkinson

Question #64888

Results question regarding a serial dilution experiment testing the bacterial coliform content with a 10 fold from 10^-1 to 10^-6. Agar used was CLED, with peptone as a nutrient.

If results showed that the most concentrated form (10^-1) showed no bacteria presence after incubation. A good number colonies present (of two types) around a mid-line concentration (10^-3) and then little or no colonies on the least diluted (10^6), how can this be explained? Is this due to the nutrient competition between the bacteria?
Thank you in advance

Expert's answer

These results can appear either due to the experimental error or due to the nutrient competition between the bacteria.