2.1.2. Isolation of Cell Envelope of *M. primoryensis* KMM 3633T

To remove surface proteins, microbial cells of *M. primoryensis* KMM 3633T were pre-treated with 5% solution of NaCl. Then, to obtain the cell envelope from the harvested microbial cells ultrasonic disintegration was used. The protein profile of the resulted total crude membrane fraction consisted of several major components: high molecular weight (MW) proteins in the form of a diffuse zone with apparent MW in the range of 95–130 kDa and a number of polypeptides with a MW in the range of 34–72 kDa (Figure 1A, lane 2). Judging by the intensity of the polypeptide bands their content in this area of molecular masses varies greatly. To detect heat-modifiable proteins in the envelope fraction, boiling in denaturing conditions was used (Figure 1A, lane 3). Several polypeptide zones in the region of 34–55 kDa became more clearly visible in MW ladder, while the protein bands in the region of high MW proteins disappeared. In addition, the intensity of the polypeptide band with MW between 43 and 35 kDa increased significantly. Obviously, the oligomeric polypeptide region of cell lysate of *M. primoryensis* KMM 3633<sup>T</sup> includes several heat-modifiable proteins which are supposed to be porins. Such behavior in the denaturing conditions of SDS-PAGE is typical for OM porins of gram-negative terrestrial bacteria, in which the oligomers dissociate into monomers after heating above the critical temperature of an irreversible conformational transition. To obtain isolated proteins from the crude cell envelope fraction of *M. primoryensis* KMM 3633T two methods were used: Sarcosyl treatment and octyl-POE extraction.
