Abstract:

The effect of dispersant formulation on oil agglomeration and biodegradation was studied systematically using microscopy over a 15-day period by contacting a model oil (hexadecane) with an oil-degrading bacterium, Alcanivorax borkumensis, in the presence Corexit 9500 (CXT), a lecithin-Tween 80 mixture (LT), lecithin (L), and Tween 80 (T). CXT and LT successfully dispersed the oil, and bacteria adhered to and colonized the dispersed oil droplets, leading to the formation of agglomerates coated with bacterial biofilms. The size and structure of the agglomerates varied with the dispersant used. With CXT the agglomerates formed quickly, were large (> 100 µm), and contained live and dead bacteria. Comparatively, with LT the agglomerates formed slowly, were smaller (~ 50 µm), and contained primarily live bacteria. Despite these differences, the extent of oil biodegradation was similar in both cases. This study shows how agglomeration and biodegradation depends on a complex interplay between the actions of the dispersant and the bacteria.

Suggested Citation:

Rocchio, Joseph. 2020. Probing the bacteria-mediated agglomeration of dispersed oil. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/H5HKMC9X

Purpose:

The purpose of this study was to examine the effect of dispersant formulation on both bacteria-mediated agglomeration of dispersed oil and biodegradation.

Data Parameters and Units:

The dataset consists of several image files and an Excel file that summarizes data from these multiple images and multiple measurements such as absorbance and intensity. The headers are as follows- Agglomerates size: Microscopy (nanometers, micrometers) and ultraviolet-visible spectroscopy (absorbance units) as functions of time (hours, days), Oil biodegradation: Gas chromatograph-mass spectrometry (intensity) as function of time (hours, days).

Methods:

Bacteria-oil agglomerates were generated during bacteria culture in synthetic seawater using baffled flasks. Samples obtained and imaged daily using optical, fluorescence, and electron microscopy. Images were processed and analyzed using ImageJ software. Samples were also analyzed by ultraviolet-visible spectroscopy.

Instruments:

ImageJ software; ultraviolet-visible spectroscopy; optical microscope; fluorescence microscope; electron microscopy

Individual Files: