Microcystin-Detoxifying Recombinant <i>Saccharomyces cerevisiae</i> Expressing the <i>mlrA</i> Gene from <i>Sphingosinicella microcystinivorans</i> B9
2023
Fernando de Godoi Silva | Daiane Dias Lopes | Ronald E. Hector | Maikon Thiago do Nascimento | Tatiana de Ávila Miguel | Emília Kiyomi Kuroda | Gisele Maria de Andrade de Nóbrega | Ken-Ichi Harada | Elisa Yoko Hirooka
Contamination of water by microcystins is a global problem. These potent hepatotoxins demand constant monitoring and control methods in potable water. Promising approaches to reduce contamination risks have focused on natural microcystin biodegradation led by enzymes encoded by the <i>mlrABCD</i> genes. The first enzyme of this system (<i>mlrA</i>) linearizes microcystin structure, reducing toxicity and stability. Heterologous expression of <i>mlrA</i> in different microorganisms may enhance its production and activity, promote additional knowledge on the enzyme, and support feasible applications. In this context, we intended to express the <i>mlrA</i> gene from <i>Sphingosinicella microcystinivorans</i> B9 in an industrial <i>Saccharomyces cerevisiae</i> strain as an innovative biological alternative to degrade microcystins. The <i>mlrA</i> gene was codon-optimized for expression in yeast, and either expressed from a plasmid or through chromosomal integration at the <i>URA3</i> locus. Recombinant and wild yeasts were cultivated in medium contaminated with microcystins, and the toxin content was analyzed during growth. Whereas no difference in microcystins content was observed in cultivation with the chromosomally integrated strain, the yeast strain hosting the <i>mlrA</i> expression plasmid reduced 83% of toxins within 120 h of cultivation. Our results show microcystinase A expressed by industrial yeast strains as a viable option for practical applications in water treatment.
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