Biomass yield ($Y=\text{biomass produced}/\text{nutrient consumed}$)

The biomass yield $Y$ converts nutrient consumption into biomass production: consuming nutrient mass $m$ produces dry biomass mass $Ym$ under the assumed constant conversion. For $Y=0.5\mathrm{g}\text{ biomass}/(\mathrm{g}\text{ nutrient})$, consumption of $8\mathrm{g}$ of nutrient produces $4\mathrm{g}$ of dry biomass. Its numerical value depends on the measurement conventions; it is not a fraction of all feed mass converted into cells. With no separate maintenance consumption, biomass production $\mu (s)x$ requires nutrient consumption $\mu (s)x/Y$ in the chemostat balance.