Escherichia Coli cell yield in media containing different carbohydrates

The objective of this study was to determine and compare the cell yield of Escherichia coli grown in minimal medium containing different concentrations of glucose (0.025%, 0.050% and 0.075%) and lactose (0.025%, 0.050% and 0.075%). Determination of the cell yield was done by oven drying the harvested cells to obtain the dry weight and analysis of the residual sugar in the liquid medium by phenol-sulfuric acid method. Highest initial concentration of glucose (596.667 ppm) and lactose (563.333 ppm) was recorded in minimal medium supplemented with 0.075% of the respective sugar. E. coli grown in 0.050% glucose (354.167 ppm) and 0.025% lactose (266.667 ppm) had the highest substrate consumed. Highest cell dry weight (μg/mL) and cell yield (μg/mL) was obtained in 0.075% glucose and 0.075% lactose. Comparing the two sugars, still, glucose had the highest cell yield (glucose 0.050% = 217.368 μg/mL and lactose 0.050% = 195.146 μg/mL; glucose 0.075% = 572.923 μg/ml and lactose 0.075% = 295.146 μg/ml). Highest Y was also recorded in highest sugar concentration (glucose 0.075% = 2.331; lactose 0.075% = 1.638). No statistical significance was observed when Y of different sugar concentrations were compared.