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Bacterial Biodeterioration
Published in Thomas Dyer, Biodeterioration of Concrete, 2017
The previous discussion identified that many of the molecules produced by bacteria in the formation of biofilms possess functional groups capable of forming bonds with metal ions. This has two important implications from the perspective of bacterial attachment to concrete surfaces. Firstly, it is likely that this ability may well provide a mechanism for the formation of strong chemical bonds between biofilms and cement hydration products at the surface. One study has observed the formation of covalent bonds between biofilms produced by Pseudomonas aeruginosa and TiO2 surfaces [33]. The compound responsible was identified as pyoverdine, which is a peptide siderophore. Siderophores are molecules which are capable of chelating iron, but also capable of forming strong bonds with other metal ions. In the case of pyoverdine, this appears to be via catecholate functional groups. Whilst this species has not been identified as one which is involved in deterioration of concrete, molecules with catecholate groups and similar are produced by many bacteria, making the formation of strong bonds with metal oxides in concrete a very likely possibility. It is also believed that divalent cations, such as calcium, can act as bridges between polysaccharide molecules, rendering biofilms stronger [34].
Damage of the swarmer Pseudomonas soil isolate cell by UVc as revealed by transmission electron microscopy
Published in International Journal of Environmental Health Research, 2023
Kloula Ben Ghorbal Salma, Mehri Abdelwahed Inès, Werhani Rim, Abdelwaheb Chatti
First, electrophoresis of pyoverdine (PVD) on ampholine containing polyacrylamide gel results in the separation of the different molecular forms of PVD present in the supernatant of an iron-starved fluorescent Pseudomonas culture. PVD isoforms appear on the electrophoresed IEF gel, exposed to UV light, as fluorescent bands with various intensities, position (pHi) and number (Meyer et al. 2002). The obtained pattern was compared to well-characterized PVD-type species, from Pyoverdine Bank available in the Laboratory of Microbiology and Genetic from the University of Louis-Pasteur in CNRS FRE 2326, Strasbourg, France. This method assigned the PVD-IEF profile of the isolated strain to the well-recognized PVD-type specie: P. aeruginosa PAO1 Siderovar I. PsS150 which showed two bands with pHi values of 8.4 and 6.9 (Figure 4).
Taxonomic, metabolic traits and species description of aromatic compound degrading Indian soil bacterium Pseudomonas bharatica CSV86T
Published in Journal of Environmental Science and Health, Part A, 2023
Balaram Mohapatra, Prashant S. Phale
Physiological studies and functional annotation of genome indicated that strain CSV86T displays beneficial eco-physiological traits.[9] Strain CSV86T produces siderophore (pyoverdine and pyochelin type, Pvd pathway) and indole acetic acid (IAA, a plant growth hormone) during degradation of aromatics. Cells showed ability to resist fusaric acid, a toxin produced by Fusarium spp. for inhibiting microbes and colonize plant tissues, at high concentration (340 µg/mL) through efflux mechanism (FUS genetic clusters).[9] Such eco-physiology traits exhibited by CSV86T has a great potential for its application as plant growth promoting bacterium to clean-up pollutants at impacted sites and increase crop yield as well as an ideal host for construction of various aromatic degradation pathways.
Advances in characterizing microbial community change and resistance upon exposure to lead contamination: Implications for ecological risk assessment
Published in Critical Reviews in Environmental Science and Technology, 2020
S. Elizabeth George, Yongshan Wan
Siderophores (“iron carrier”, Greek) are small, high-affinity iron-chelating compounds secreted by microorganisms such as bacteria and fungi. Microorganisms excrete siderophores to chelate iron and transport it back across the cell membrane (Neilands, 1995). However, these same relatively low molecular weight compounds can also bind heavy metals, such as Pb, and reduce toxicity (O'Brien et al., 2014). In Pseudomonas aeruginosa PAO1, Pb bound to the siderophore pyoverdine but was not transported into the cell (Braud et al., 2009). Some heavy metals, such as Cd, Co, gallium (Ga), Hg, Mn and Zn, inhibited iron uptake, however Pb did not (Braud et al., 2009). Furthermore, it did not inhibit pyoverdine production (Braud et al., 2009). A Pb resistant strain of Pseudomonas aeruginosa (strain 4EA), isolated from soil contaminated with Pb battery waste, increased pyochelin and pyoverdine production coupled with reduced cell size in the presence of Pb (Naik & Dubey, 2011). Excreted siderophores also scavenged Pb, resulting in the production of Pb precipitates through phosphatase action and formation of Pb phosphates (Naik & Dubey, 2011; O'Brien et al., 2014).