Efficiency of pyoverdines in iron removal from flocking asbestos waste: An innovative bacterial bioremediation strategy

Abstract

The use of asbestos-containing products has been banned in many countries since the beginning of the 80's due to its carcinogenic properties. However, asbestos is widely present in private and public buildings, resulting in the need to process a vast amount of asbestos-containing waste. Among the current technologies for the destruction of asbestos fibers, biodegradation by fungi, lichens, and, more recently, bacteria has been described. We previously reported the involvement of the bacterial siderophore pyoverdine in the release of iron from the two asbestos groups, serpentines and amphiboles. Among the large diversity encountered in the pyoverdine family, we examined whether these siderophores can alter flocking asbestos waste as well. All the tested pyoverdines were efficient in chrysotile-gypsum and amosite-gypsum weathering, although some exhibited higher iron dissolution. Iron was solubilized by pyoverdines from Pseudomonas aeruginosa and mandelii in a time-dependent manner from chrysotile-gypsum within 24 hours.Renewal of pyoverdine-containing supernatant every 24 or 96 hours allowed iron removal from chrysotile-gypsum at each cycle, until a limit was reached after 42 days of total incubation. Moreover, the dissolution was concentration-dependent, as demonstrated for the pyoverdine of

A Review of Asbestos Bioweathering by Siderophore-Producing Pseudomonas: A Potential Strategy of Bioremediation

“…Interestingly, David et al [72,80] showed a large decrease of iron content in asbestos fibers after long-term alteration with PVDs and confirmed the active dissolution by the siderophores (Figure 8). This process of bioweathering could lead to a reduction in asbestos toxicity.…”

“…Recently, studies of David et al [72,[78][79][80] corroborate that these siderophores are also involved in the dissolution of other silicate minerals such as asbestiform minerals. Indeed, asbestos is an iron source for various microorganisms.…”

“…Due to the importance of the large variety and amount of siderophores in soil, the role of siderophore as a general mechanism in the dissolution of minerals such as clays, iron oxides or asbestos silicates has been well-studied for many microorganisms [46,71,72]. Therefore, the essential element such as iron could be available via Fe 3+ -siderophore complex formation at the mineral surface and transfer in the soil solution for uptake by microorganisms or plants.…”

“…Recently, David et al [72,80] investigated the efficiency of various PVDs to scavenge iron from ACW. According to materials, the more efficient PVDs to extract iron are different ( Figure 6).…”

“…The long-term bioweathering of ACW by renewal cycles using apo-PVD solutions highlighted iron release over time for AF or AC fFiuwaste ( Figure 7). A siderophore dissolution mechanism of ACW has been suggested [18,72]. During the first renewal cycles, PVDs probably adsorb to the fiber's surface and might release iron present in the brucite layer due to magnesium substitution.…”