Petroleum hydrocarbon degrading bacteria associated with chitosan as effective particle-stabilizers for oil emulsification

Abstract

The effective emulsification of oil and retention of the stability of this emulsion in sea water is an important requirement for the remediation process following a marine oil spill. To identify alternate dispersants for emulsifying oil following a spill, we investigated oil-in-water emulsions stabilized by self-assembled complexes of a hydrophilic petroleum hydrocarbon degrading bacteria, Bacillus cereus S-1, with the linear polysaccharide chitosan. We found that the addition of chitosan improves the ability of hydrophilic Bacillus cereus S-1 to function as an effective emulsifier. The self-assembled complex of Bacillus cereus S-1 and chitosan is able to adsorb on the interface and stabilize oil-in-water emulsions for months.Confocal laser scanning microscope (CLSM) imagings and SEM results showed that the oil-in-water emulsions were stable against coalescence by formation of a thin film of bacteria-chitosan complex.Bacillus cereus S-1 associated with chitosan in the aqueous phase gave rise to a network, which was also responsible for the emulsion stability. The ability of this complex work in seawater was still very effective.In addition to stabilization, the addition of chitosan dramatically enhanced the oil degradation rate of Bacillus cereus S-1. Due to the sustainability and low environmental impact of chitosan and petroleum hydrocarbon degrading bacteria, this is an environmentally friendly and inexpensive way to treat marine oil spills.

Characterization of biosurfactant lipopeptide and its performance evaluation for oil-spill remediation

“…11 Biosurfactants are promising dispersants in oil-spill remediation, owning to their environmentally friendly and biodegradable properties. 12 Chemical surfactants could be replaced with biosurfactants and this change would diminish the environmental impact of traditional dispersants. 8,13,14 Lipopeptide produced by microorganisms is one of the representative biosurfactants and has showed great potential applications in food, 15 medicine, 16 microbial enhanced oil recovery, 17 and other elds.…”

The physical–biological processes of petroleum hydrocarbons in seawater/sediments after an oil spill

“…Strain S-1 isolated from crude oil contaminated sediment in our previous study was used for the biodegradation experiment. 15,16 Sequence analysis of the 16S rDNA gene, BLAST sequence comparison and phylogenetic analysis conrmed that strain S-1 was affiliated with Bacillus cereus (KF033125). 15 Strain S-1 can catabolize crude oil as a carbon and energy source, and it prefers alkanes to aromatics.…”

Targeted and Stimulus-Responsive Delivery of Surfactant to the Oil–Water Interface for Applications in Oil Spill Remediation

“…The use of particles in stabilizing emulsions is an environmentally benign alternative to the use of surfactants and has been explored extensively due to the possibility of using particles with natural clays. − In particle-stabilized emulsions, also known as Pickering emulsions, , particles spontaneously adsorb at the oil–water interface upon energy input through wave action to create emulsion droplets and provide a steric barrier to droplet coalescence. While particle stabilized emulsions are effective in preventing coalescence and reforming an oil slick, they are not intrinsically effective in reducing the interfacial tension to values that lead to droplets small enough to be sustained in the water column.…”