Temperature effects on growth, metabolome, lipidic profile and photosynthetic pigment content of Microglena antarctica (chlorophyceae): A comprehensive analysis

Abstract

Antarctic microalgae have evolved a wide range of adaptations to survive at extreme environmental conditions. This study aimed to explore the physiological and biochemical processes occurring in Microglena antarctica (Chlorophyceae) in response to changes in temperature. M. antarctica cultivated at three distinct temperatures (4 °C, 8 °C and 16 °C) exhibited variations in growth patterns, metabolomes, fatty acid methyl esters (FAMEs) profile and photosynthetic pigment concentrations. Our results highlighted a decrease in growth at 16 °C, confirming the cryophilic nature of this species. The growth rates at the exponential phase were observed to decrease progressively with an initial rate of (0.29 ± 0.05 d−1) at the culturing temperature of 4 °C, followed by 8 °C (0.24 ± 0.09 d−1), and further reduction at 16 °C (0.16 ± 0.05 d−1). An integrative untargeted metabolomics approach combining mass spectral libraries and novel in–silico tools was employed to improve feature annotation and to provide additional information on features chemical classes. Significant differences in M. antarctica annotated compounds, chemical classes and whole metabolomes were observed among 4, 8 and 16 °C. Finally, targeted analyses were performed to evaluate changes in lipid profiles and photosynthetic pigment content. Higher percentages of polyunsaturated fatty acids (PUFAs) were observed at 4 and 8 °C, approximately 65.00 % of total FAMEs, and decreased to 60.71 % at 16 °C. Monounsaturated fatty acids (MUFAs) significantly increased at 16 °C, reaching up to 10.96 % of total FAMEs, in contrast to 4 °C and 8 °C, where the content of MUFAs was around 5.00 %. Additionally, chlorophyll a and carotenoid content increased by 50–100 % at 16 °C compared to lower temperatures. The present work highlights temperature–related responses in M. antarctica biochemical profile, combining untargeted and targeted approaches, and physiology, by growth analysis.