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Microbial Bioremediation
Published in Gustavo Molina, Zeba Usmani, Minaxi Sharma, Abdelaziz Yasri, Vijai Kumar Gupta, Microbes in Agri-Forestry Biotechnology, 2023
Anamika Harshvardhan, Purabi Saikia
In-situ bioremediation is a procedure that is carried out at its site of contamination (USEPA, 2006; 2012), in which chemotaxis plays a fundamental role, as microbes have chemotactic ability to move towards contaminated areas. In case of the in-situ bioremediation process, oxygen and nutrients are added to the contaminated sites to hasten the microbial multiplication and accelerate the process of bioremediation (Hazen, 2010). It is considered to provide greater cost-benefit than ex-situ bioremediation because the removal process is considered to be more useful than the immobilization of contaminants. It also reduces the contact of workers with the contaminated medium (Thomé et al., 2018). In-situ bioremediation is further bifurcated into intrinsic in-situ bioremediation and engineered in-situ bioremediation (Hazen, 2010).
Role of Indigenous Microbial Community in Bioremediation
Published in Vineet Kumar, Vinod Kumar Garg, Sunil Kumar, Jayanta Kumar Biswas, Omics for Environmental Engineering and Microbiology Systems, 2023
Bhupendra Pushkar, Pooja Sevak
It is well accepted that in situ bioremediation process has a relatively low impact on the environment and is economically friendly as compared to other chemical and physical treatment methods (Miao et al., 2021). Pollutants are highly diverse, and thus, it becomes extremely difficult to devise a universal technology for different types of pollutants. Bioremediation using indigenous microbial communities is thoughtful as the indigenous microbial communities are selectively enriched according to the environmental conditions to degrade the pollutant (Wang et al., 2018). Indigenous microbial communities respond differently to various pollutants, which is correlated to their degradation capacity (Gouveia et al., 2018). Microbes sensitive to toxic pollutants diminish upon exposure to high concentrations of pollutants, while the tolerant ones survive and increase in abundance. The physiological adaptation and genetic modifications are involved in the enhancement of abundance of tolerant microbes by replacing the sensitive microbes (Khan et al., 2010). The microbial community has a much specialized hierarchical structure where a decentralized metabolic network works with each other. Such organization enables great plasticity with high resilience power, which undergoes continuous changes with changing environmental conditions (Tikariha and Purohit, 2020).
Ecological and Health Implications of Heavy Metals Contamination in the Environment and Their Bioremediation Approaches
Published in Ram Naresh Bharagava, Sandhya Mishra, Ganesh Dattatraya Saratale, Rijuta Ganesh Saratale, Luiz Fernando Romanholo Ferreira, Bioremediation, 2022
Remediation by employing microbes can be carried out in situ or ex situ. In situ bioremediation is done at the site of contamination either by supplementing contaminated soils with nutrients to stimulate the activity of native microorganisms, or by adding new microorganisms in the existing pool to augment the biodegradative capability of indigenous microbial population. Ex situ bioremediation is done by transferring the polluted material to another area for management. Microbes adopt various ways to interact with heavy metals, such as by changing their oxidation states, by immobilizing them, by volatilizing or by increasing the solubility of the toxic metal, thus allowing them to flush away easily from the site. The interaction of microbes with metals is a complicated process, and it depends on various factors such as metal type, temperature, pH, moisture content, soil structure and nutrients (Gupta et al. 2016).
Bioremediation of heavy metal polluted soil using plant growth promoting bacteria: an assessment of response
Published in Bioremediation Journal, 2022
Ifeoma Anthonia Okpara-Elom, Charles Chike Onochie, Michael Okpara Elom, Emmanuel Ezaka, Ogbonnaya Elom
In in-situ bioremediation, the pollution is eliminated directly at the place where it occurs or at the site of contamination. It is employed in degradation of contaminants in saturated soils. The method, apart from being cheaper, uses harmless microbes to degrade the chemicals (Girma 2015). In-situ bioremediation can also be categorized into intrinsic bioremediation and engineered in-situ bioremediation. In in-situ bioremediation, indigenous or naturally-occurring microbial populations are stimulated by feeding them with nutrients and oxygen so as to boost their metabolic activities. Engineered in-situ bioremediation involves the introduction of certain microorganisms to the sites of contamination. This kind of bioremediation hastens the process of degradation by enhancing the physiochemical conditions, so as to encourage the growth of microorganisms (Girma 2015).
A review of strategies for the detection and remediation of organotin pollution
Published in Critical Reviews in Environmental Science and Technology, 2018
Christopher Finnegan, David Ryan, Anne-Marie Enright, Guiomar Garcia-Cabellos
Bioremediation is a process which involves the uses of microorganisms (bacteria, fungi, or microalgae) to degrade or remove contaminates in soil, sediment, or water, (Adams et al., 2015 Uqab et al., 2016). Modern bioremediation is credited to George Robinison for the use of microbes to remediate a large oil spill in California in the late 1960s (Adams et al., 2015 Uqab et al., 2016). Bioremediation is now acknowledged as the main pathway for the removal of organotin compounds (OTCs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), pesticides and volatile, and nonvolatile organic compounds from marine sedimentary environments and soils (Kotrikla, 2009; Jin et al., 2011; Cruz et al., 2014; Germaine et al 2015; Khanolkar et al., 2015; Dzionek et al., 2016; Uqab et al., 2016). In-situ remediation techniques are preferred over ex situ ones, because the excavation of contaminated sediments or soils will have a high cost and individual excavators are exposed to adverse health risks of contaminants. Also in situ treatments are advantageous when there is no possibility to transfer the polluted matrix due to the contamination affecting a large area (Dzionek et al., 2016) There are three main strategies for in situ bioremediation with microorganisms. The first is natural attenuation or removal of contamination by the indigenous microbial population (Adams et al., 2015). The main drawback to this method is that on average only 10% of total microbes will have the ability to degrade the pollutant, therefore this method takes a long time, however there is little to no cost involved. Bioaugmentation involves specific degraders of the contaminate being introduced into the sites matrix to increase the efficiency of the degrading process (USEPA, 2007; Adams et al., 2015). The difficulties with bioaugmentation include the fact that the microbes must be able to move through the pores in the soil, survive in a foreign habitat and compete for nutrients with the indigenous population of microorganisms. The advantages include the decrease in time taken for remediation of site compared to natural attenuation and cheaper cost compared to other methods (USEPA, 2007; Adams et al., 2015). Biostimulation is the addition of nutrients through an organic substrate (compost, straw) or electron acceptors (i.e., nitrogen, oxygen, carbon and phosphorus) to accelerate the in situ processes by modifying the physical and chemical parameters of the site matrix (Sakultantimetha et al., 2010a; Jin et al 2011). The main advantage of this method is faster site remediation time and higher percentage removal rate of the target contaminant and the main disadvantage includes cost compared to other two strategies for in situ bioremediation with microorganisms (Sakultantimetha et al., 2010a).