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Omics Reflection on the Bacterial Escape from the Toxic Trap of Metal(loid)s
Published in Vineet Kumar, Vinod Kumar Garg, Sunil Kumar, Jayanta Kumar Biswas, Omics for Environmental Engineering and Microbiology Systems, 2023
Jayanta Kumar Biswas, Monojit Mondal, Vineet Kumar, Meththika Vithanage, Rangabhashiyam Selvasembian, Balram Ambade, Manish Kumar
Bioaugmentation is a technique for bioremoval of TM contaminants from polluted areas that involve the introduction of specialized bacteria or genetically modified bacteria that are capable of combating the TM contaminations. This is a very efficient and sustainable in situ technique that has a high degree of substrate specificity (Mrozik and Piotrowska-Seget 2010). On-site intervention of bioaugmented bacteria is frequently affected by abiotic and biotic stressors (Rahman et al. 2020). High concentration of TMs at polluted areas can prevent rapid growth and activity of allochthonous bacteria (Nanda et al. 2019). Another limiting factor for the growth of bioaugmented bacteria is nutrient shortage (Rahman et al. 2020). In this account, Mondal et al. (2019) showed that a wastewater bacterial strain Bacillus sp. KUJM2 has greatly immobilized multiple metal(loid)s (As, Cd, Cu, and Ni) in the soil. Another study used the bioaugmentation approach to remove Hg through volatilization from polluted soils using Sphingobium SA2 and a nutrient supplement (Mahbub et al. 2016).
Approaches for increasing bioremediation capabilities of plants and microorganisms towards heavy metals and radionuclides
Published in Rym Salah-Tazdaït, Djaber Tazdaït, Phyto and Microbial Remediation of Heavy Metals and Radionuclides in the Environment, 2022
Rym Salah-Tazdaït, Djaber Tazdaït
An alternative method is the use of genetically modified bacteria cells killed before they come into contact with the polluted matrix. Because DNA is stable in the environment, dead cells can transfer plasmids to other organisms. In addition, even if such cells obviously cannot multiply in the environment, they could release enzymes there or carry on their surface molecules capable of degrading or absorbing pollutants. However, their use would require developing effective methods of contacting the pollutant within the contaminated matrix and repeating them throughout the treatment. For the first time in the United States, a team from the University of Minnesota at St Paul used a recombinant strain of E. coli manipulated to overexpress an atrazine chlorohydrolase to decontaminate soil polluted by atrazine, a herbicide widely used in agriculture. Before their application to the surfaces to be treated, the bacteria had been killed by a chemical agent, glutaraldehyde. In eight weeks, the authors found a reduction in the concentration of atrazine by 77%. They consider this to be the minimum efficiency of their technique because it was applied in late fall when temperatures were already low enough. These authors also noted that the enzymatic activity was preserved for several months after treating the bacteria with glutaralde-hyde. This stability is undoubtedly one of the keys to the effectiveness of the treatment (Strong, McTavish, Sadowsky, and Wackett 2000, 91).
Encapsulation Technology-Based Self-Healing Cementitious Materials
Published in Ghasan Fahim Huseien, Iman Faridmehr, Mohammad Hajmohammadian Baghban, Self-Healing Cementitious Materials, 2022
Ghasan Fahim Huseien, Iman Faridmehr, Mohammad Hajmohammadian Baghban
A lengthy period of between 14 and 21 days is needed for biological agents in the concrete with appropriate curing conditions to enact self-healing of crack formations, as per the results. Bacteria in the alkaline concrete environment produce a lower precipitation rate, explaining the ample time taken. Higher precipitation rates and increased bacteria lifespans could be achieved via the creation of genetically modified bacteria cultures following further interdisciplinary investigations. In such a case when further investigations produce results, quicker healing of wider crack formations may be possible. Through biological action, quicker and more effective autonomous healing can be attained by placing an emphasis on the vital aspect of controlling the width of crack formations [23]. Following autonomous healing, highly effective restoration of original properties can be achieved via incorporating hybrid fibers to regulate width of cracks [24–25]. Healing agents and products can place themselves close to the faces of crack formations via the amalgamation of polymer fibers and steel that also act to hinder the width of cracks [24].
Beneficial bacteria associated with Mimosa pudica and potential to sustain plant growth-promoting traits under heavy metals stress
Published in Bioremediation Journal, 2020
Saidu Abdullahi, Hazzeman Haris, Kamarul Zaman Zarkasi, Hamzah Ghazali Amir
Increased rate of abiotic stresses like that of heavy metals adversely affect plant growth and productivity (Xie et al. 2016), environmental processes (Rahman and Singh 2019) and also microbial community and activities (Jiang et al. 2019). Despite the effects of the heavy metals, microbes have been shown to play important roles to overcome abiotic stress through their different activities at the rhizosphere zone (Enebe and Babalola 2018). Application or present of PGPRs in the heavy metals stress zone is proven option to decrease these stresses and is widely in practice (Singh et al. 2019; Barbosa Felestrino et al. 2017; Islam et al. 2016). Heavy metal tolerant PGPRs in the rhizosphere solve the problem by modulating plant growth as well as by altering physicochemical properties of soil to enhance rapid detoxification or removal of heavy metals from soil (Mishra, Singh, and Arora 2017). Heavy metals contaminated soils have a very strong selecting pressure, that enables the growth of different metal tolerant microbes (Karthik and Arulselvi 2017). Some naturally and/or genetically modified bacteria such as PGPRs have the ability of tolerating, degrading, transforming, detoxifying, or chelating various toxic chemicals resulting in better strategies of reducing or eliminating environmental pollution (e.g., heavy metal stress) (Mosa et al. 2016).
Environmental remediation using metals and inorganic and organic materials: a review
Published in Journal of Environmental Science and Health, Part C, 2022
Haragobinda Srichandan, Puneet Kumar Singh, Pankaj Kumar Parhi, Pratikhya Mohanty, Tapan Kumar Adhya, Ritesh Pattnaik, Snehasish Mishra, Pranab Kumar Hota
Microbial cells are immobilized to support matrix through covalent bonding, adsorption, affinity immobilization, entrapment in polymers and semipermeable membrane encapsulation.71 Genetically modified bacteria Ochrobactrum tritici capable of accumulating As was immobilized on polyethylene (PE) net after sputtered modified by depositing polytetrafluoroethylene (PTFE) thin films without uncompromised bacterial activity. Bacterial biofilm thus generated could effectively remove As from wastewaters. Bacterial strain Rhodanobacter A261 was immobilized onto PTFE thin films which could remove 120 µM of U6+ out of 500 µM U6+ at pH 5.0 in batch processing under nutrient-limited growth conditions.33
Direct visualization of oil degradation and biofilm formation for the screening of crude oil-degrading bacteria
Published in Bioremediation Journal, 2020
Mengyuan Zheng, Weiyao Wang, Kyriakos Papadopoulos
A massive flux of hydrocarbons into the Gulf of Mexico, caused by the Macondo/Deepwater Horizon oil spill on April 20, 2010 has stimulated the growth of petroleum/hydrocarbon degraders in oil-contaminated Gulf water, beach sands and salt marshes (Baelum et al. 2012; Beazley et al. 2012; Dubinsky et al. 2013; Kostka et al. 2011; Lu et al. 2012; Rodriguez-r et al. 2015). Such microbes can be isolated, harvested, enhanced, preserved and utilized to remediate the next oil spill (Kostka et al. 2011; Rahman et al. 2002), however, the screening process of proper oil degraders is challenging due to the massive number of potential oil degraders that can be identified through phenotype characterization in every sampling. Knowing the taxonomic rank of these microbes is not enough since 99% of the bacteria cannot be cultured under a laboratory environment (Li and Vederas 2009), therefore it is critical to identify those microbes which can both proliferate in synthetic media and still be able to bioremediate the next oil spill after being preserved in laboratory condition (Colombo et al. 2011; Liu et al. 2014; Liu, Hu, and Liu 2016; Patowary et al. 2018). During the process of bioremediation, non-genetically modified bacteria are expected to increase the removal rate of contaminants and gradually die down as the concentration of pollutants decreases. In consuming hydrocarbons, bacteria produce biosurfactant which can decrease the surface tension of the oil. Based on their biosurfactant-production ability, microbes can also be introduced into porous medium oil reservoirs to increase the crude’s recovery rate (microbial enhanced oil recovery) (Gudiña et al. 2012; Ke et al. 2018; Kryachko and Voordouw 2014; Ron and Rosenberg, 2002; Thibodeaux et al. 2011).