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

Abstract

Asbestos, silicate minerals present in soil and used for building constructions for many years, are highly toxic due primarily to the presence of high concentrations of the transition metal iron. Microbial weathering of asbestos occurs through various alteration mechanisms. Siderophores, complex agents specialized in metal chelation, are common mechanisms described in mineral alteration. Solubilized metals from the fiber can serve as micronutrients for telluric microorganisms. The review focuses on the bioweathering of asbestos fibers, found in soil or manufactured by humans with gypsum (asbestos flocking) or cement, by siderophore-producing Pseudomonas. A better understanding of the interactions between asbestos and bacteria will give a perspective of a detoxification process inhibiting asbestos toxicity.

Internal Transcribed Spacer and 16S Amplicon Sequencing Identifies Microbial Species Associated with Asbestos in New Zealand

“…Asbestos is the commercial name for a group of six naturally-occurring, fibrous silicate minerals in the amphibole (actinolite, amosite, anthophyllite, crocidolite, and tremolite) or serpentine (chrysotile) groups [ 1 , 2 ]. Historically, chrysotile, crocidolite, and amosite have been the most widely used worldwide because of their strength, heat, chemical resistance, and electrical insulation properties [ 3 , 4 , 5 , 6 ].…”

“…Inhalation of asbestos fibres can cause lung inflammation and later development of asbestosis, lung cancer, and mesothelioma [ 7 ]. This has been linked experimentally in part to iron at the surface of asbestos fibres generating hydroxyl radicals and reactive oxygen species (ROS), which cause DNA damage [ 2 , 7 , 8 ]. For this reason, the use of asbestos is banned in many countries (approx.…”

“…In most countries, large amounts of asbestos exists within building stock, buried in landfills, and in contaminated soil [ 10 , 11 ]. Mechanical, thermal, and chemical treatment options do exist, but these are prohibitively expensive, and they are not effective for contaminated soil, where only small numbers of asbestos fibres may be present in a large volume of soil [ 2 , 12 ].…”

“…All six types of asbestos contain iron, either as part of the fibre structure, or in the case of chrysotile, replacing Mg 2+ or Si in the outer layer of the fibre [ 13 , 14 ]. Iron is an essential nutrient for bacteria, fungi, and plants, but it is often not readily biologically available due to its relatively low solubility [ 2 , 15 , 16 ]. To access sufficient iron for metabolism, many microbes produce organic acids, or iron-chelating siderophores [ 2 , 3 ].…”

Recent progress in understanding the ecology and molecular genetics of soil mineral weathering bacteria

“…Based on these properties they have been proposed to be used as biological fertilizers in agriculture [12,13] and as bioactive agents to manage building construction materials (i.e., asbestos) [14]. However, field experiments and microbial inoculations gave contrasting results, evidencing the need to have a better understanding of the ecology of the MWe bacteria and to characterize the associated genetic basis in order to effectively control and utilize them.…”