Dear Sabastian,

Cell growth was measured by monitoring the optical density 600 nm (OD600) in a spectrophotometer . OD600 was converted into dry cellular weight (biomass concentration) using a standard curve (1 OD600 = 0.37 g/L of dry cellular weight). Specific growth rates (μ) were determined by fitting the biomass data versus time to exponential regressions. The biomass yield (YX/S) was estimated as the coefficient of linear regression of biomass concentration versus substrate concentration (glucose, arabinose, glycerol, gluconate, or glucose plus other carbon source) in grams of biomass/mmolC of substrate(s). The specific carbon consumption rate (qS) was determined as the ratio of μ to YX/S.

I didn't get it exactly. Is biomass yield the slope of curve biomass(g/L) vs. substrate (g/L)? 

Hamidreza Hajfarajollah Biomass yield is the ratio of the biomass (X) produced to the amount of substrates (S) consumed. Y = X/S