Effects and applications of sub-lethal ultrasound, electroporation and UV radiations in bioprocessing

Advances in bioprocess technology involving microbial cells have led to increased and improved production of beneficial new products and bioactive compounds. However, the semipermeable barrier of the cell membrane often retards the efficient productivity or reaction rate of the cells. Physical treatments such as ultrasound, electroporation and UV radiation provide an efficient approach to increase membrane permeability, leading to enhanced productivity of microbial cells. It is important to note that extensive membrane permeabilization by these physical treatments could be detrimental to cell viability leading to lower yield. An appropriate selection of sublethal dosage and intensity of these physical treatments are critical to preserve the viability of cells and at the same time maintain their bioprocess applications. Despite the promising applications of these physical treatments, safety issues related to possible genotoxicity or mutation of cells upon treatments have been raised. This genotoxic effect of physical treatments could be prevented if appropriate measures are taken, without compromising their bioprocess potentials. The current review highlights the effect of sublethal physical treatments such as ultrasound, electroporation and UV radiation on the viability of cells, their potential bioprocess applications, and the possibility of mutations.