3.3 Directing Evolution in the Laboratory
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Consider the concept of directed evolution of enzymes as catalysts that break down molecules of interest. The concept has been considered for the clean-up of petroleum-contaminated soil. What approach do you think could be followed?
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June 22, 2021 at 1:37 pm
Utilize directed protein evolution to take existing families of cutinase or other degradative proteins, pinpoint an optimized protein for which can utilize petroleum as a substrate out of a protein library, an induce alterations and mutagenesis for an improved enzyme specific to this function
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July 21, 2021 at 11:38 pm
Biodegradation of petroleum by genetically engineered bacteria could be an option. Some bacteria have been shown to degrade or metabolize petroleum hydrocarbons. The acting enzymes can be purified from these microorganisms to determine the responsible gene or genes’ DNA sequence. Those isolated genes can be subject to induced mutagenesis then transferred to a model microorganism like E.coli. The model microorganisms now expresse enzymes derived from the mutated genes library. The model microorganisms can be challenged in the lab in a petroleum rich environment to see which microorganism biodegrades the best. If feasible, (such as if the enzyme is stable outside of the cells and can be mass produced), the enzyme from the selected microorganism can then be purified and used to clean-up contaminated soil.If not feasible, the microorganism expressing the effective enzyme can itself be used to clean-up the soil.
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November 21, 2021 at 8:48 pm
I like Genevieve’s answer. I am not an expert in the field but taking advantage of already pre-existing biology and just to retrofit it to our needs/function seems the logic path to me.
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August 14, 2022 at 5:58 pm
I like the idea of selectively targeting the enzyme composition of tumors.
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September 14, 2022 at 5:49 am
Hello Ladies and Gentlemen,
Pre-existing enzymes that use the oil can be isolated, perhaps amplified.
Then the spill gets coralled and eaten.
But what happens then?
I do research. There is a region of Valles Marinaris on Mars that is green. It is halfway on the canyon, and on the lower half.
Did this escape notice of scientists or is it only a landslide revealling subsoil?
When the oil eating starts, what stops it? The molecular markers need to also be in place for predicted time of digestion and to self- destruct.
Or, similar to the oops in Valles Marinaris, it will continue if not self-destructed. Mad science is science beyond control, and science is not beyond control.
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August 22, 2025 at 1:17 am
Directed evolution offers a promising approach to engineer enzymes capable of efficiently degrading petroleum hydrocarbons in contaminated soils, where natural biodegradation is typically slow and incomplete. The process starts by selecting enzymes already known to act on hydrocarbons—such as alkane monooxygenases, cytochrome P450s, laccases, or aromatic ring dioxygenases—as the parent scaffolds. Large libraries of variants can then be generated using techniques like error-prone PCR, DNA shuffling, or saturation mutagenesis to introduce diversity. High-throughput screening methods are applied to identify improved variants, using assays that detect the breakdown of hydrocarbons into measurable intermediates, fluorescence or colorimetric reporters, or microdroplet-based selections with crude oil emulsions. Importantly, the screening systems should mimic real soil conditions, incorporating variables such as fluctuating pH, temperature, salinity, and the presence of heavy metals or humic substances, to ensure that selected enzymes remain effective outside the laboratory. Through multiple iterative cycles, variants with enhanced activity, stability, and solvent tolerance can be isolated.
After identifying promising enzyme variants, the next step is to optimize their performance for field applications. This involves engineering additional traits such as greater thermal and pH stability, resistance to soil-derived inhibitors, and longer half-lives under environmental conditions. Enzymes may also be fused with soil-binding domains, ensuring they adhere to soil particles and maintain activity without leaching away. Furthermore, combining multiple evolved enzymes into coordinated pathways enables complete mineralization of hydrocarbons, preventing the accumulation of toxic intermediates. These pathways can be expressed in robust microbial hosts like Pseudomonas putida or Bacillus subtilis, which naturally thrive in soil environments, while incorporating genetic safeguards such as kill switches or synthetic auxotrophies to address biosafety concerns. Alternatively, for non-GMO solutions, purified or immobilized enzymes can be mass-produced and delivered directly to contaminated sites, using carriers such as biochar, zeolites, or hydrogels to stabilize them and control their release.
The final phase is deployment and field validation, which depends on regulatory frameworks and site-specific constraints. In regions where the use of engineered microbes is restricted, enzyme-only formulations provide a practical and environmentally safe option, applied as soil amendments with periodic re-dosing. Where permitted, engineered microbial strains offer a more sustainable, self-propagating solution, often enhanced with biosurfactant production to increase hydrocarbon bioavailability. Field trials should build on laboratory and mesocosm studies, assessing reductions in total petroleum hydrocarbons and polycyclic aromatic hydrocarbons, alongside ecotoxicity tests to verify environmental safety. By integrating directed evolution with robust delivery methods and careful ecological monitoring, it becomes feasible to accelerate natural bioremediation processes, transforming petroleum-contaminated soils into recoverable land while ensuring both effectiveness and sustainability.
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November 10, 2025 at 9:31 am
We could try to find or create the catalyst that breaks down petroleum according to the concept of directed evolution and use it in order to break down the petroleum in the contaminated soil.
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