*Article* **Combination of Hypotonic Lysis and Application of Detergent for Isolation of Polyhydroxyalkanoates from Extremophiles**

**Ivana Novackova 1, Xenie Kourilova <sup>1</sup> , Katerina Mrazova 2, Petr Sedlacek <sup>1</sup> , Michal Kalina <sup>1</sup> , Vladislav Krzyzanek <sup>2</sup> , Martin Koller 3,4 and Stanislav Obruca 1,\***


**Abstract:** Production of polyhydroxyalkanoates (PHA), microbial biopolyesters, employing extremophilic microorganisms is a very promising concept relying on robustness of such organisms against microbial contamination, which provides numerous economic and technological benefits. In this work, we took advantage of the natural susceptibility of halophilic and thermophilic PHA producers to hypotonic lysis and we developed a simple and robust approach enabling effective isolation of PHA materials from microbial cells. The method is based on the exposition of microbial cells to hypotonic conditions induced by the diluted solution of sodium dodecyl sulfate (SDS) at elevated temperatures. Such conditions lead to disruption of the cells and release of PHA granules. Moreover, SDS, apart from its cell-disruptive function, also solubilizes hydrophobic components, which would otherwise contaminate PHA materials. The purity of obtained materials, as well as the yields of recovery, reach high values (values of purity higher than 99 wt.%, yields close to 1). Furthermore, we also focused on the removal of SDS from wastewater. The simple, inexpensive, and safe technique is based on the precipitation of SDS in the presence of KCl. The precipitate can be simply removed by decantation or centrifugation. Moreover, there is also the possibility to regenerate the SDS, which would substantially improve the economic feasibility of the process.

**Keywords:** polyhydroxyalkanoate (PHA); sodium dodecyl sulfate (SDS); PHA isolation; extremophiles; halophiles; thermophiles; *Halomonas halophila*; *Schlegelella thermodepolymerans*
