Achieving pH control in microalgal cultures through fed-batch addition of stoichiometrically-balanced growth media

Table 1 Algebraic expression of stoichiometric coefficients for common nitrogen sources

Nitrogen source	Stoichiometric coefficients
Nitrogen source	α	Ψ	δ	λ
N₂	1	$y 2$	$x 2$	$1 + x 4 − z 2$
NH₄⁺	1	y	$x 2 − 2 y$	$1 + x 4 − y − z 2$
NO₃⁻	1	y	$x 2$	$1 + x 4 + 3 y 2 − z 2$
CO(NH₂)₂	$1 − y 2$	$y 2$	$x 2 − y$	$1 + x 4 − 3 y 4 − z 2$

The stoichiometric coefficients were determined algebraically from Equation 1 and are given in terms of biomass composition (x, y, z) for various nitrogen sources when extracellular metabolites are not considered.