Benzo[a]pyrene (BaP) is recognized as a potentially carcinogenic and mutagenic hydrocarbon, and thus, its removal from the environment is a priority. The use of thermophilic bacteria capable of biodegrading or biotransforming this compound to less toxic forms has been explored in recent decades, since it provides advantages compared to mesophilic organisms. This study assessed the biotransformation of BaP by the thermophilic bacterium Bacillus licheniformis M2-7. Our analysis of the biotransformation process mediated by strain M2-7 on BaP shows that it begins during the first 3 h of culture. The gas chromatogram of the compound produced shows a peak with a retention time of 17.38 min, and the mass spectra shows an approximate molecular ion of m/z 167, which coincides with the molecular weight of the chemical formula CH(COOH), confirming a chemical structure corresponding to phthalic acid. Catechol 2,3-dioxygenase (C23O) enzyme activity was detected in minimal saline medium supplemented with BaP (0.33 U mg of protein). This finding suggests that B. licheniformis M2-7 uses the meta pathway for biodegrading BaP using the enzyme C23O, thereby generating phthalic acid as an intermediate.
Environmental pollution derived from heavy metals (HMs) is a worldwide problem and the implementation of eco-friendly technologies for remediation of the pollution are necessary. The metallophores are low-molecular weight compounds that have important biotechnological applications in agriculture, medicine and biorremediation. The aim of this work was to isolate the HM resistant bacteria from soils and sediments of Lerma-Chapala basin, and to evaluate their abilities to produce metallophores and to promote plant growth. A total of 320 bacteria were recovered, and the siderophores synthesis was detected in cultures of 170 of the total isolates. The Lerma-Chapala Basin bacteria also produced metallophores for all the tested metal ions and presented a greater production of As 3+ metallophores. The members in genera Delftia and Pseudomonas showed siderophores production above 92 percent siderophore units (psu). In addition, the hydroxamate was the most common fuctional group among the analyzed siderophores. Also, the bacteria showed high HM resistance especially to Zn 2+ , As 5+ and Ni 2+ . Our results evidenced that Lerma-Chapala basin bacteria or their metallophores could be employed in biorremediation process or may even have potential for applications in other biotechnological purposes.
Hypersaline environments are those with salt concentrations 9-10 times higher (30-35% of NaCl) than sea water (3.5% of NaCl). At high concentrations of soluble salts, cytoplasm-mainly of bacteria and archaea-is exposed to high ionic strength and achieves osmotic equilibrium by maintaining a cytoplasmic salt concentration similar to that of the surrounding media. Halophilic enzymes are extremozymes produced by halophilic microorganisms; they have similar characteristics to regular enzymes but different properties, mainly structural. Among these properties is a high requirement of salt for biological functions. Furthermore, the discovery of enzymes capable of degrading biopolymers offer a new perspective in the treatment of residues from oil deposits, under typically high conditions of salt and temperature, while giving valuable information on heterotrophic processes in saline environments.
Environmental pollution derived from heavy metals (HMs) is a worldwide problem and the implementation of eco-friendly technologies for remediation of the pollution are necessary. The metallophores are low-molecular weight compounds that have important biotechnological applications in agriculture, medicine and biorremediation. The aim of this work was to isolate the HM resistant bacteria from soils and sediments of Lerma-Chapala basin, and to evaluate their abilities to produce metallophores and to promote plant growth. A total of 320 bacteria were recovered, and the siderophores synthesis was detected in cultures of 170 of the total isolates. The Lerma-Chapala Basin bacteria also produced metallophores for all the tested metal ions and presented a greater production of As3+ metallophores. The members in genera Delftia and Pseudomonas showed siderophores production above 92 percent siderophore units (psu). In addition, the hydroxamate was the most common fuctional group among the analyzed siderophores. Also, the bacteria showed high HM resistance especially to Zn2+, As5+ and Ni2+. Our results evidenced that Lerma-Chapala basin bacteria or their metallophores could be employed in biorremediation process or may even have potential for applications in other biotechnological purposes.
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