Determining E. coli Growth Kinetics Through Experimentation with a Sartorius Bioreactor System: A Quantitative Study

This paper presents an experimental study of E. coli TOP10 growth kinetics and lactic acid production using a Sartorius bench-top stirred bioreactor. A single batch culture was operated at 37 °C under non-aerated, oxygen-limited conditions with Lysogeny Broth as the medium. Over 130 minutes, cell growth, pH, and dissolved oxygen concentration were observed to evaluate bacterial behavior and acid production. Optical density at 600 nm was converted to cell mass density, and pH measurements were used to estimate lactic acid concentration, assuming lactic acid was the main acidic species. Data showed increasing biomass, decreasing pH, and oxygen depletion. Linear regression of the exponential phase yielded an effective growth rate constant of approximately 0.0087 min⁻¹, corresponding to a doubling time of 79.7 minutes. Lactic acid production scaled nonlinearly with biomass, fitting a power-law index of 2.06. These results indicate that oxygen limitation reduced the apparent growth rate compared to aerobic E. coli culture, yet still allowed measurable acid accumulation.