Crystallization of antibiotics and other biologically active substances from water solutions represents an important stage of their biotechnological production. The process is based on a sharp reduction of a target compound solubility caused by either temperature decrease, or supersaturation of a solution. A preconditioning of a solution, i.e., its evaporation with a simultaneous temperature decrease seems to be an optimal technical solution, especially advantageous for the treatment of thermolabile substances. This paper describes the technology and equipment for the pre-crystallization treatment of solutions of various substances produced by the biotechnological and chemical industries. The proposed preconditioning technology includes ultrasonic dispersion of a solution and formation of an aerosol with a large integral evaporation surface followed by condensation. Comparing to common tubular evaporators used in various industrial processes, this technology provides about equal productivity and, at the same time, lower energy consumption, since it does not require the heating and the further cooling of a solution needed to evaporate and condensate the solvent, respectively, that prevents undesirable effect of high temperature on thermolabile compounds. In addition, the technology prevents the damage of thermolabile compounds, improves the efficiency of the further crystallization process due to the ultrasound-stimulated formation of crystallizing nuclei, and provides a solvent distillate suitable for the further re-use. The designed device for preconditioning has been successfully tested using culture broth of Streptomyces sp. containing a feed antibiotic virginiamycin; such treatment with the further crystallization in standard crystallizers has resulted in the efficient formation of equal-sized antibiotic crystals.

Supplementation of fermentation media with synthetic resins is used in the process of biotechnological production of antibiotics and other biologically active substances to prevent the auto-inhibition of the biosynthesis processes due to the binding of secreted target metabolites to a sorbent and their removal from the fermentation volume. The efficiency of a sorbent application may be improved via the ultrasonic stimulation of the antibiotic sorption from cultural broth during fermentation, and the similar stimulation of the reverse process (desorption) during its isolation and purification. In this study, the possibility of the use of ultrasound to improve the processes of sorption and desorption of virginiamycin, a feed antibiotic produced by the highly active strain Streptomyces sp. S 15-30, to/from an Amberlite XAD-16 synthetic resin selectively binding this antibiotic, has been evaluated. According to the obtained results, the ultrasonic treatment with frequency of 22 kHz and acoustic energy density up to 0.05 W·s/cm 3 does not disrupt cell membranes, i.e., does not violate biotechnological processes. At the same time, such treatment increases the sorption capacity of the sorbent in ~1.4 times. The similar ultrasonic treatment of a sorbent at the acoustic field with energy density of 0.5 W·s/cm 3 almost tenfold accelerates desorption of virginiamycin from the resin but does not destroy the sorbent and provides a possibility to its re-use after regeneration. The revealed effects of the ultrasonic treatment may be integrated into the technology of the virginiamycin biosynthesis, isolation, and purification to improve the efficiency of its industrial production.