Effect of chromate ions on marine microalgae Phaeodactylum tricornutum

Abstract

Effect of chromate ions on the culture of a marine diatom Phaeodactylum tricornutum was studied using an M-PEA-2 fluorimeter, which carries out simultaneous measurement of fluorescence induction and redox transformations of the P₇₀₀ pigment within a millisecond range. Chromate ions were shown to inhibit electron transport in PS II and decrease the rate of Q_А reduction. This results in decreased values of the quantum yield of electron transport in PS II (ϕ_Eo) and performance index (PI_ABS), lower rates of P700 reduction, and increased energy (DI0/RC) and ΔpH-dependent nonphotochemical quenching (q_E). Emergence of the slow component of P₇₀₀ reduction was observed, indicating the activation of cyclic transport in the presence of chromate. Performance index (PI_ABS), which was the most sensitive parameter, may be recommended for detection of chromate ions at early stages of their toxic action. The fluorescence parameter F_O is promising application in biotesting to assess the algal growth rates.