Magnesium ions mitigate biofilm formation of Bacillus species via downregulation of matrix genes expression

Abstract

The objective of this study was to investigate the effect of Mg2+ ions on biofilm formation by Bacillus species, which are considered as problematic microorganisms in the food industry. We found that magnesium ions are capable to inhibit significantly biofilm formation of Bacillus species at 50 mM concentration and higher. We further report that Mg2+ ions don't inhibit bacterial growth at elevated concentrations; hence, the mode of action of Mg2+ ions is apparently specific to inhibition of biofilm formation. Biofilm formation depends on the synthesis of extracellular matrix, whose production in Bacillus subtilis is specified by two major operons: the epsA-O and tapA operons. We analyzed the effect of Mg2+ ions on matrix gene expression using transcriptional fusions of the promoters for eps and tapA to the gene encoding β galactosidase. The expression of the two matrix operons was reduced drastically in response to Mg2+ ions suggesting about their inhibitory effect on expression of the matrix genes in B. subtilis. Since the matrix gene expression is tightly controlled by Spo0A dependent pathway, we conclude that Mg2+ ions could affect the signal transduction for biofilm formation through this pathway.

Proteomic Effects of Magnesium Stress on Biofilm Associated Proteins Isolated from Cellulolytic Bacillus licheniformis YNP5-TSU

“…Magnesium stress, can affect many protein expression pathways related to biofilm and subsequent cellulose degradation via alternative carbohydrate utilization. While our study was focused on the effects of low magnesium stress, other studies have been able to show the same is true for environments with high (50 mM) MgSO 4 concentrations as well [35]. Oknin et al were able to show that Mg 2+ ions are specific to inhibition of biofilm formation, which depends on the maturation of the extracellular matrix.…”

“…Oknin et al were able to show that Mg 2+ ions are specific to inhibition of biofilm formation, which depends on the maturation of the extracellular matrix. This is controlled by the epsA-O and tapA operons, and linked to the gene expression of β-galactosidase [35,36]; a connection between biofilm and cellulase production. Mg 2+ ions play a key role in the growth and metabolic functions of bacteria.…”

The LuxS Based Quorum Sensing Governs Lactose Induced Biofilm Formation by Bacillus subtilis

“…One milliliter of each sample was collected and centrifuged at 5000 rpm for 2 min. The supernatant was discarded, the pellet was re-suspended and 3 μl of the suspension placed on a glass slide was visualized in a transmitted light microscope using Nomarski differential interference contrast (DIC), at 40× magnification ( Pasvolsky et al, 2014 ; Oknin et al, 2015 ). Furthermore, a confocal laser scanning microscope (CLSM) was used to visualize cyan fluorescent protein (CFP) or green fluorescent protein (GFP) expression.…”

The Interface Between Degradable Mg and Tissue

“…55 There are no systematic studies about the effect of bacteria on the degradation of Mg or the composition of the degradation layer. This is partially caused by the antimicrobial effect of fast degrading Mg alloys 56 or because Ag or Zn were used as alloying elements. 57,58 On the other hand, it is reported that, on slowly degrading Mg-based materials, bacteria can survive very well, 59 although the degradation layer is then so thin that its analysis is challenging.…”