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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
Functional degrading genes encode metabolic enzymes such as alkane hydroxylase genes, ring-hydroxylating dioxygenase α-subunit (RHDα) genes, alkylsuccinate synthase gene (assA), and benzylsuccinate synthase gene (bssA), which are important in the aerobic and anaerobic degradation of PHCs. A well-studied alkane monooxygenase is a non-haem integral membrane protein encoded by alkB gene that activates the initial step of aerobic aliphatic hydrocarbon metabolism. The phenol monooxygenase systems and naphthalene dioxygenase encoded by phe and nah genes are involved in the metabolism of PAHs by catalysing the single or two atoms of molecular oxygen to aromatic rings. Oil-polluted sites exhibit higher abundance of genes and transcripts associated with aromatic compound degradation, mainly meta- and ortho-pathways as compared to the pristine sites. Catabolic genes alkB, nah, and phe increase in relative abundance in oil pollution in the following order: alkB > nah > phe. The intrinsic characters of monooxygenase and the requirement of oxygen and cofactors cause the alkane-degrading microbes having alkB, nah, and phe genes to accumulate majorly at surface soil than in the deeper layer where conditions are more anaerobic and anoxic (Liu et al., 2019).
Molecular Probes and Biosensors in Bioremediation and Site Assessment
Published in Subhas K. Sikdar, Robert L. Irvine, Fundamentals and Applications, 2017
Gary S. Sayler, Udayakumar Matrubutham, Fu-Min Menn, Wade H. Johnston, Raymond D. Stapleton
Studies of groundwater aquifer material at Columbus Air Force Base, which had previously been exposed to an intentional injection of hydrocarbons including benzene, ethyl benzene, p-xylene, and o-dichlorobenzene, during the macrodispersion experiment (MADE 2) were also conducted (Stapleton and Sayler, 1995). This study demonstrated the disappearance of up to 94% of the contaminants over a 15-month period (Boggs et al., 1993). Microbiological degradation of the hydrocarbons was proposed as the mechanism of disappearance, but no data exist to support this hypothesis. As a follow-up, the Natural Attenuation Study (NAT) has been initiated to include microbiological aspects in the fate of hydrocarbons in the subsurface. The initial site characterization of the native microbial community showed that bacteria possessing the genotype to degrade the contaminant mixture to be used in the NAT study exist. DNA hybridization studies with the gene probes alkB (alkane monooxygenase), nahA, nahH/xylE (catechol 2,3-dioxygenase), todC1C2, and xylA (xylene monooxygenase) showed that the study site maintains these degradative populations at approximately 106 bacteria/gram of sample even in pristine control samples. This initial characterization will be used to compare future microbial community responses after the hydrocarbons have been released at the study site.
Investigation of microbial community changes in petroleum polluted sediments during hydrocarbons degradation
Published in Soil and Sediment Contamination: An International Journal, 2022
Mouna Mahjoubi, Simone Cappello, Santina Santisi, Afef Najjari, Yasmine Souissi, Ameur Cherif
Overall, these results are in agreement with other studies that reported the rapid stimulation and the abundance of Alcanivorax sp. on microcosm oil spill simulation and in sediment treated with oil and inorganic nutrients (Bacosa et al. 2016; Cappello et al. 2007a; Genovese et al. 2014; Head, Jones, and Röling 2006). Alcanivorax is well known as an efficient oil-degrading agent and plays an important role in the biological treatment based on their ability to degrade alkanes. This observation has been linked to catabolic genes that encode for alkane degrading enzymes, such as AlkB which are well known for Alcanivorax (Guibert et al. 2016; Matturro et al. 2016). This genus has been widely distributed in various hydrocarbon contaminated environments worldwide, such as in the Mediterranean Sea, Antarctic Sea, Atlantic Sea, Japan Sea, South China Sea and North Sea (Bookstaver et al. 2015; Schneiker et al. 2006). Since petroleum is a complex mixture of hydrocarbons, diverse bacterial species able to degrade each class of these hydrocarbons were detected after enrichment. The dominance of Alcanivorax was correlated to the presence of alkanes that constitute the major fraction of crude oil