Effect of Isothiocyanates on the Activity of <i>Lactobacillus plantarum</i> Exposed to Irradiation

Abstract

Two isothiocyanates, i.e., sulforaphane (SFA) and sulforaphene (SFE), are suggested to be used as an alternative chemopreventive diet. This study was focused on the effect of SFA and SFE on Lactobacillus plantarum, which has been subjected to the irradiation (2-50 Gy). The cultures grown in De Man, Rogosa and Sharpe (MRS) and Tryptone Soya Broth (TSB) were compared in terms of bacteria physiological activity under tested conditions. Broth composition notably influenced the bacteria growth kinetic parameters, as well as culture response to the oxidative stress. Activity of L. plantarum cells after irradiation was evaluated by their dehydrogenase (DHA) and quinone-reductase (QR) activities. The enzyme activity was quantified in living cells. Bacterial cultures obtained in MRS and TSB broth, demonstrated contrasting characteristics in their enzyme activities. The MRS-grown culture did not show any QR activity, whereas the TSB-grown cells showed a non-linear response towards gamma-irradiation with a maximum inhibition being at 10 Gy. Addition of SFA or SFE in concentration of 1 µg/mL to the cultures before irradiation exposure recovered the QR activity from 23% in a non-amended variant up to 102% and 121%, respectively, taking the non-irradiated non-amended variant as 100%.