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8.5 Role of Biosurfactants in Microbial Enhanced
Oil Recovery
Microbial enhanced oil recovery utilizes microbes and their metabolic processes for
the exploitation of oil from reservoirs. Microorganisms synthesize surface active
compounds which decrease oil-rock surface tension by reducing capillary forces
that hinder the mobility of oil through pores of rock (Banat 1995). Microbial biosurfactants assist in mobilization of hydrocarbons, emulsification, and breakdown of
oil films (Perfumo et al. 2010). However, multiple effects of microorganisms such
as production of gases and acids, fall in viscosity of oil, plugging by biomass
growth, decrease in interfacial tension by microbial surfactants, and breakdown of
large organic molecules contribute to the oil removal. Interestingly, all these factors
facilitate the decrease in oil viscosity and easy recovery. MEOR is proven to be
economical in comparison with chemically enhanced oil recovery, as microbes synthesize competent surface active molecules on inexpensive substrates (Sarafzadeh
et al. 2014). Numerous experimental studies highlighted the application of microbial surfactants in microbial enhanced oil recovery (Bordoloi and Konwar 2009; Liu
et al. 2015). Apparently, Yan et al. (2012) achieved an oil recovery of up to 91.5%
from oily sludge using rhamnolipids produced by Pseudomonas aeruginosa F-2 in
in vitro and small-scale experiments. A Clostridium strain NJS-4 facilitated
improved oil recovery of 26.7% and 10.1% in sand pack experiments and core flood
experiments correspondingly (Arora et al. 2014). Likewise, Zhao et al. (2015) demonstrated enhanced displacement of 8.33% crude oil in core flooding experiments
during in situ production of rhamnolipid by Pseudomonas aeruginosa strain
SG. More recently, Najafi-Marghmaleki et al. (2018) reported a novel Alcaligenes
faecalis, producing 8.2% and 5.2% further oil recovery in microbial enhanced oil
recovery process in a carbonate oil reservoir.
8.6 Role of Biosurfactants in Petroleum Industry
and Remediation of Oil Spills
Despite being major pollutants of the environment, petroleum hydrocarbons are
main energy resources. Petroleum hydrocarbons vary in their vulnerability to microbial action and usually dissociate in the subsequent order of declining susceptibility:
n-alkanes > branched alkanes > low molecular weight aromatics > cyclic alkanes
(Leahy and Colwell 1990). Previous studies reported that biosurfactants can be synthesized primarily on water insoluble substrates like petroleum hydrocarbons (Ward
2010). Petroleum-polluted locations have more possibility of facilitating favorable
situations for microbial surfactant producers, and the related bioremediation abilities were primarily investigated (De Sousa and Bhosle 2012; Syakti et al. 2013).
Commonly used physicochemical methods merely transfer pollutants from an environmental medium to a new one and generate lethal by products. Furthermore, crude
K. V. Deepika et al.
8.5 Role of Biosurfactants in Microbial Enhanced
Oil Recovery
Microbial enhanced oil recovery utilizes microbes and their metabolic processes for
the exploitation of oil from reservoirs. Microorganisms synthesize surface active
compounds which decrease oil-rock surface tension by reducing capillary forces
that hinder the mobility of oil through pores of rock (Banat 1995). Microbial biosurfactants assist in mobilization of hydrocarbons, emulsification, and breakdown of
oil films (Perfumo et al. 2010). However, multiple effects of microorganisms such
as production of gases and acids, fall in viscosity of oil, plugging by biomass
growth, decrease in interfacial tension by microbial surfactants, and breakdown of
large organic molecules contribute to the oil removal. Interestingly, all these factors
facilitate the decrease in oil viscosity and easy recovery. MEOR is proven to be
economical in comparison with chemically enhanced oil recovery, as microbes synthesize competent surface active molecules on inexpensive substrates (Sarafzadeh
et al. 2014). Numerous experimental studies highlighted the application of microbial surfactants in microbial enhanced oil recovery (Bordoloi and Konwar 2009; Liu
et al. 2015). Apparently, Yan et al. (2012) achieved an oil recovery of up to 91.5%
from oily sludge using rhamnolipids produced by Pseudomonas aeruginosa F-2 in
in vitro and small-scale experiments. A Clostridium strain NJS-4 facilitated
improved oil recovery of 26.7% and 10.1% in sand pack experiments and core flood
experiments correspondingly (Arora et al. 2014). Likewise, Zhao et al. (2015) demonstrated enhanced displacement of 8.33% crude oil in core flooding experiments
during in situ production of rhamnolipid by Pseudomonas aeruginosa strain
SG. More recently, Najafi-Marghmaleki et al. (2018) reported a novel Alcaligenes
faecalis, producing 8.2% and 5.2% further oil recovery in microbial enhanced oil
recovery process in a carbonate oil reservoir.
8.6 Role of Biosurfactants in Petroleum Industry
and Remediation of Oil Spills
Despite being major pollutants of the environment, petroleum hydrocarbons are
main energy resources. Petroleum hydrocarbons vary in their vulnerability to microbial action and usually dissociate in the subsequent order of declining susceptibility:
n-alkanes > branched alkanes > low molecular weight aromatics > cyclic alkanes
(Leahy and Colwell 1990). Previous studies reported that biosurfactants can be synthesized primarily on water insoluble substrates like petroleum hydrocarbons (Ward
2010). Petroleum-polluted locations have more possibility of facilitating favorable
situations for microbial surfactant producers, and the related bioremediation abilities were primarily investigated (De Sousa and Bhosle 2012; Syakti et al. 2013).
Commonly used physicochemical methods merely transfer pollutants from an environmental medium to a new one and generate lethal by products. Furthermore, crude
K. V. Deepika et al.