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Interconnection between PHA and Stress Robustness of Bacteria
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Stanislav Obruca, Petr Sedlacek, Iva Pernicova, Adriana Kovalcik, Ivana Novackova, Eva Slaninova, Ivana Marova
The microorganisms which are able to grow with a high concentration of heavy metals are known as metallotolerants. There are no microbial strains that require the presence of heavy metals for their growth but some of their production metabolic pathways could be directly caused or at least enhanced by the presence of heavy metal ions in the solutions where cells occur. A typical example could be seen for the PHA model microorganism Cupriavidus necator when, moreover, nitrogen limitation together with an excess of a carbon source led to a higher PHB amount in cells. Also, the presence of heavy metal ions such as copper, iron or nickel led to enhanced production of PHA. The resistance against high concentrations of different heavy metals including copper, nickel, zinc, cadmium, lead, arsenic, mercury and others was described for the microbial strain Cupriavidus metallidurans CH34 isolated from the metal processing factory. All defense mechanisms were described for this strain. The resistance against heavy metals could be associated with genetic determinants occurring within plasmids, transposons or chromosomal DNA when the transfer of genes causing the resistance is used by many microorganisms as a strategy of how to survive this stress. Enzymes of the PHA biosynthetic pathway were characterized and it was observed that more copies of individual genes are located in different places in the genome in contrast with the genome of C. necator. Moreover, some of them showed dissimilarities considering the substrate specificity which could lead to the ability of utilization of different carbon sources for PHA production as well as an ability to incorporate a wider range of monomers [113–115].
Effect of Support Media on Heavy Metals Removal in Constructed Wetlands: Inoculated with Metallotolerant Strains
Published in María del Carmen Durán-Domínguez-de-Bazúa, Amado Enrique Navarro-Frómeta, Josep M. Bayona, Artificial or Constructed Wetlands, 2018
Leonel Ernesto Amabilis-Sosa, Marcela Arroyo-Ginez, Ruth Pérez-González, Adriana Roé-Sosa, Landy Irene Ramírez-Burgos, María del Carmen Durán-Domínguez-de-Bazú
In experiments related with adsorption, support media with metallotolerant microorganisms were capable of accumulating a considerable amount of heavy metals, probably due to biofilm development. This was experimentally supported by elemental analysis results.
Toxic metals bioremediation potentials of Paenibacillus sp. strain SEM1 and Morganella sp. strain WEM7 isolated from Enyigba Pb–Zn mining site, Ebonyi State Nigeria
Published in Bioremediation Journal, 2021
O. U. Orji, J. N. Awoke, C. Aloke, O. D. Obasi, B. Oke, M. Njoku, N. N. Ezeani
The elevation of toxic metal levels in the environment usually triggers initiation of processes culminating to metal tolerance (Voica et al. 2016). Toxic metal pollution serves as a propelling force in the co-selection of toxic metal- and antibiotic-resistant microorganisms (Seiler and Berendonk 2012). Metallo-tolerant microorganisms capable of thriving and detoxifying elevated quantities of dissolved toxic metals are extremophiles of relevance for fundamental and applied researches (Margaryan, Panosyan, and Popov 2010). Polluted environments with crude industrial and urban wastes and samples of natural environment with extreme levels of toxic metals are the best source for isolation of metallotolerant microorganisms. They have been found in all bacterial groups studied (Afzal et al. 2017; Babavalian et al. 2013; Igiri et al. 2018; Divakar, Sameer, and Bapuji 2018; Akcay and Kaya 2019; Sanjeeda, Abu, Sangita 2020) and may perform a critical role in the biogeochemical cycling of toxic heavy metals (Margaryan, Panosyan, and Popov 2010). They might be novel sources for functional bio-sorbents of heavy metals and may perhaps have many applications in bioremediation of metal-polluted sites. Regularity of appearance of bacteria tolerant to a particular heavy metal could be exploited as biomarker of environmental pollution.