Mg2+ reduces biofilm quantity in Acidithiobacillus ferrooxidans through inhibiting Type IV pili formation

Abstract

Bioleaching is a promising process for 350 million tons of Jinchuan low-grade pentlandite. But high concentration of Mg2+ is harmful to bioleaching microorganisms. Interestingly, biofilm formation can improve leaching rate. Thus, it is actually necessary to investigate the effect of Mg2+ stress on Acidithiobacillus ferrooxidans biofilms formation. In this study, we found that 0.1 and 0.5 M Mg2+ stress significantly reduced the total biomass of biofilm in a dose-dependent manner. The observation results of extracellular polymeric substances and bacteria using confocal laser scanning microscopy showed that the biofilm became thinner and looser under Mg2+ stress. Whereas 0.1 and 0.5 M Mg2+ stress had no remarkable effect on the bacterial viability, the attachment rate of Acidithiobacillus ferrooxidans to pentlandite was reduced by Mg2+ stress. Furthermore, sliding motility, twitching motility and the gene expression level of pilV and pilW were inhibited under Mg2+ stress. These results suggested that Mg2+ reduced biofilm formation through inhibiting pilV and pilW gene expression, decreasing Type IV pili formation and then attenuating the ability of attachment, subduing the active expansion of biofilms mediated by twitching motility. This study provided more information about the effect of Mg2+ stress on biofilm formation and may be useful for increasing the leaching rate in low-grade pentlandit.

Bioactive Dental Resin Composites with MgO Nanoparticles

“…Oknin et al reported that Mg 2+ ions drastically downregulated the expression of two major operons in Bacillus species, which was tightly correlated to the synthesis of the extracellular matrix and thus mitigated biofilm formation . Tang et al suggested that Mg 2+ could suppress the growth of type IV pili, attenuating bacterial adhesion and subduing biofilm formation mediated by twitching motility . Additionally, the dissolution of Mg 2+ into the medium produces hydrogen and magnesium hydrate, exerting a pH buffering effect and shifting it toward the physiological pH .…”

“…75 Tang et al suggested that Mg 2+ could suppress the growth of type IV pili, attenuating bacterial adhesion and subduing biofilm formation mediated by twitching motility. 76 Additionally, the dissolution of Mg 2+ into the medium produces hydrogen and magnesium hydrate, exerting a pH buffering effect and shifting it toward the physiological pH. 77 This may help in disturbing cariogenic biofilm formation as well as inhibiting the decalcification of tooth hard tissue.…”

Growth in Ever-Increasing Acidity Condition Enhanced the Adaption and Bioleaching of Leptospirlium Ferriphilum

“…At pH 0.7, the iron oxidation rate of the evolved L. ferriphilum still showed 320 mg L -1 h -1 at 20 gL -1 MgSO 4 . It was worthy to note that the higher concentration of MgSO 4 , the smaller the biomass produced by both the evolved strain and the starting strain, indicating that high concentration of MgSO 4 is detrimental to the production of biomass, previous studies also demonstrated that high concentration of Mg 2+ reduced the bio lm quantity (Tang et al, 2018).Therefore, the enhanced iron oxidation capacity may due to high ionic conductivity environment that improved electron transfer (Li et al, 2014).…”

Optimization of divalent metal cations for maximal concentration of Monacolin K in Monascus M1 by response surface methodology

“…But there was no significant effect between the biomass of Monascus M1 and the concentration of Mg 2+ . Tang et al (2018) showed that Mg 2+ stress significantly reduced the total biomass in a dose-dependent manner within a certain concentration range in Acidithiobacillus ferrooxidans. But in our present study, we did not find any correlation between the biomass and the concentration of Mg 2+ in Monascus M1 (Figure 1C).…”