Estimation of Heterogeneity of Photosystem II Complexes of Chlorella vulgaris Algae Cells under Nitrogen Starvation Using a Mathematical Model

The study of microalgae cell responses to such stress factors as mineral nutrient deficiency is an important ecological task. Changes in the photosynthetic apparatus are reflected in the kinetics of experimentally measured chlorophyll fluorescence induction curves. Various mathematical methods are developed to analyze changes in the shape of curves, allowing rapid analysis of a large number of curves. The paper demonstrates the use of a simple mathematical model of photosystem II (PSII) to assess changes in the PSII parameters of a Chlorella vulgaris microalgae cell culture growing under nitrogen deficiency in the medium. The model describes transitions between three key PSII states that differ in the oxidation state of its components. The mathematical model revealed an increase in the proportion of reaction centers containing smaller antennae as well as an increase in the proportion of inactive oxygen-releasing complexes.