Impact of simulated microgravity on bioremoval of heavy-metals by Lactobacillus acidophilus ATCC 4356 from water

There are several reports about the effect of gravity removal on some characteristics of microorganisms due to possible change in surface layer thickness and adherence properties. In this study, bioremoval efficiency of Lactobacillus acidophilus ATCC 4356 from water under simulated microgravity conditions was investigated. Furthermore, pretreatment effects (untreated, NaOH, and heat pretreated) of L. acidophilus ATCC 4356 on heavy metal removal was evaluated on microgravity, as our previous research showed impact of pretreatment on adherence properties of probiotics to environmental metals. The results showed that ability of L. acidophilus for arsenic adsorption enhanced following heat-pretreatment in simulated and normal gravity. Moreover, in both conditions of simulated microgravity and normal gravity NaOH-treated L. acidophilus increased the removal of cadmium and lead. In none of the conditions, pretreatment of lactobacillus affects mercury removal. Evaluation of stability of binding of L. acidophilus-heavy metal was investigated to check irreversibility of complex formation between microorganisms and metals in simulated gastrointestinal conditions. Data showed release of heavy metals from complex in normal gravity. Obtained results of this research show the favorable potential of simulated microgravity condition to increase bioremoval capacity of L. acidophilus for heavy metals.