Development of a Multistrain Bacterial Bioreporter Platform for the Monitoring of Hydrocarbon Contaminants in Marine Environments

Abstract

Petroleum hydrocarbons are common contaminants in marine and freshwater aquatic habitats, often occurring as a result of oil spillage. Rapid and reliable on-site tools for measuring the bioavailable hydrocarbon fractions, i.e., those that are most likely to cause toxic effects or are available for biodegradation, would assist in assessing potential ecological damage and following the progress of cleanup operations. Here we examined the suitability of a set of different rapid bioassays (2-3 h) using bacteria expressing the LuxAB luciferase to measure the presence of short-chain linear alkanes, monoaromatic and polyaromatic compounds, biphenyls, and DNA-damaging agents in seawater after a laboratory-scale oil spill. Five independent spills of 20 mL of NSO-1 crude oil with 2 L of seawater (North Sea or Mediterranean Sea) were carried out in 5 L glass flasks for periods of up to 10 days. Bioassays readily detected ephemeral concentrations of short-chain alkanes and BTEX (i.e., benzene, toluene, ethylbenzene, and xylenes) in the seawater within minutes to hours after the spill, increasing to a maximum of up to 80 muM within 6-24 h, after which they decreased to low or undetectable levels. The strong decrease in short-chain alkanes and BTEX may have been due to their volatilization or biodegradation, which was supported by changes in the microbial community composition. Two- and three-ring PAHs appeared in the seawater phase after 24 h with a concentration up to 1 muM naphthalene equivalents and remained above 0.5 muM for the duration of the experiment. DNA-damage-sensitive bioreporters did not produce any signal with the oil-spilled aqueous-phase samples, whereas bioassays for (hydroxy)biphenyls showed occasional responses. Chemical analysis for alkanes and PAHs in contaminated seawater samples supported the bioassay data, but did not show the typical ephemeral peaks observed with the bioassays. We conclude that bacterium-based bioassays can be a suitable alternative for rapid on-site quantitative measurement of hydrocarbons in seawater.

Kinetic modeling and half life study on bioremediation of crude oil dispersed by Corexit 9500

“…Some fractions of oil can cause chronic sub-acute toxicological effect (reduced growth and reproduction, poor health, low recruitment rates), which can alter population dynamics and disrupt tropic interactions and the structure of natural communities within ecosystems [1]. After weathering of the surface oil layer by evaporation, dispersion, and dissolution and by sedimentation of heavier slicks or after physical removal of the major part of oil slicks, dissolved hydrocarbons in the water may still be toxic for organisms [2]. It is estimated that more than 2 million tons of oil enters marine environments from ships and other sea-based activities annually.…”

Detection of Organic Compounds with Whole-Cell Bioluminescent Bioassays

“…Similar to the TOL-encoded pathway, the tbu pathway is regulated by the TbuT protein, which activates the PtubA1 promoter in the presence of a BTEX inducer compound. Building upon this pathway, Tecon et al [14] developed an E. coli -based bioreporter that harbors a pPROBE-LuxAB-TbuT plasmid whereby the TbuT regulator acts on the PtubA1 promoter when a BTEX inducer compound is present to transcribe the luxAB genes from A. fischeri . Because only the luxA B genes were present, and not the full luxCDABE operon, all assays using this reporter required the addition of the n-decanal substrate prior to bioluminescent production.…”

Whole-cell biochips for online water monitoring

“…When the designated environmental conditions are met, the transcription of the lux operon is promoted and a light signal is produced that is proportional in intensity to the magnitude of the stimulus. [7][8][9][10][11][12] To date, the use of bioluminescent recombinant reporter bacteria has been mostly restricted to laboratory environments. Other reports have suggested innovative designs for their integration in deployable systems, including systems for continuous water monitoring.…”