Exploring Tetraselmis chui microbiomes-functional metagenomics for novel catalases and superoxide dismutases.

The focus on microalgae for applications in several fields, e.g. resources for biofuel, the food industry, cosmetics, nutraceuticals, biotechnology, and healthcare, has gained increasing attention over the last decades. In this study, we investigate the microbiome of the cultured microalga Tetraselmis chui (T. chui) to highlight their potential for health benefits. In this context, biomolecules like antioxidants play a crucial role in the well-being of living organisms as they metabolise harmful reactive oxygen species (ROS) to reduce oxidative stress. Impaired processing of ROS leads to damaged cells and increases the risk of cancer, inflammatory diseases, and diabetes, among others. Here, we identify, characterise, and test bacterial antioxidants derived from the T. chui microbiome metagenome dataset. We identified 258 genes coding for proteins with potential antioxidant activity. Of those, four novel enzymes are expressed and identified as two superoxide dismutases (SOD), TcJM_SOD2 and TcIK_SOD3, and two catalases (CAT), TcJM_CAT2 and TcIK_CAT3. Extensive analyses characterised all implemented enzymes as active even in concentrations down to 25 ng*ml