Effect of electroporation in a continuous flow system on bioaccumulation of magnesium, zinc and calcium ions in Lactobacillus rhamnosus B 442 cells

Biomass of Lactobacillus rhamnosus B 442 was subjected to the continuous electroporation using an elec-troporator with a flow chamber (length of 10 cm, distance between electrodes 0.25 cm, stream width 0.25 cm, flow speed 10 mL/min) to improve accumulation of calcium, magnesium and zinc in the cells. For all tested ions, the following parameters were applied: voltage of 250 V (E = 1 kV/cm), 570 V (E = 2.28 kV/cm), 950 V (E = 3.8 kV/cm), and 1400 V (E = 5.6 kV/cm, the positive control), a frequency of 10 Hz, a pulse width of 100 mu s and 30 electrical pulses. The use of PEF increased the accumulation of mag-nesium, zinc and calcium by 39, 73 and 162%, respectively, compared to the control. Positive correlation was found between ion accumulation and membrane permeability for zinc and magnesium. For calcium, the initial increase in permeability resulted in higher ion accumulation, but with a further increase of this parameter at 3.8 kV/cm, its decrease was observed caused by a drop in cell viability. Total number of bac-teria ranged from 1.67 x 10(8) (for the cultures supplemented with calcium) to 1.34 x 10(12) cfu/mL (for the cultures supplemented with magnesium). (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The biomass of Lactobacillus rhamnosus B 442 was subjected to continuous electroporation to improve accumulation of calcium, magnesium, and zinc. Electroporation increased accumulation of magnesium, zinc, and calcium, with a positive correlation between ion accumulation and membrane permeability for zinc and magnesium. However, an increase in calcium permeability at higher electric field strengths led to a decrease in cell viability.