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V. Vijayalekshmi et al.
1 Introduction
Biosurfactants refer to any biomolecules which exhibit characteristics like surfaceactive and are found to be amphipathic in nature, which can be produced extracellularly by various microbes including bacteria, fungi and yeasts. They form aggregates at the interfaces amid different fluid polarities, wherein decreasing the surface
(Saravanan and Vijayakumar 2012). The unique features of microbial surfactants
include biodegradability, emulsifying and demulsifying ability, wetting and penetrating agents, tolerance to temperature, pH, ionic strength, low toxicity and viscosity
reducing agents make them most suitable for remediation of environmental contamination, environmental safety (Akbari et al. 2018) and finds application in food,
pharmaceutical and allied industries (Shekhar et al. 2015; Sharma et al. 2018). Oil
spills and various other hydrocarbon contaminants in the soil and aquatic environment is becoming a significant focus of attention in the today world. Absorbents and
synthetic organic products like lime, plastic polymers and cellulose-based materials,
polyurethane foams, polypropylene and elastomers were preferred as the commercial
sorbents in the oil spill cleanup considering the properties of good hydrophobicity,
uptake capacity and oil recovery (Adebajo et al. 2003; Seo et al. 2018), but then it
faced the problems of low degradability comparing to the naturally occurring mineral
and vegetable products (Teas et al. 2001). Such disadvantages has to be mitigated via
microbialy generated surfactants. Microorganisms exposed to oil-contaminated sites,
develop the potential to harness hydrocarbons as carbon and energy for its metabolic
activities. Biosurfactants increase the substrate bioavailability for microorganisms
and interacts with the cell surface, thereby increasing the surface hydrophobicity,
thus allowing substrates to accumulate faster within the bacterial cells (Liu et al.
2017). In comparison with its chemical counterparts, biosurfactants are very particular, potent and competent under an extensive range of oil and receptacle environment and may only require meagre quantities. Because of these attributes, they are
preferred in different industrial processes and physicochemical phenomena, wherein
they attribute enhanced solubility, increased mobility (Pacwa-Płociniczak et al. 2011;
Rufino et al. 2014). Microbial biosurfactant with all these unique properties is considered to be a best green alternative potent source when comparing to other methods
for clearing oil spills and plays a promising role in bioremediation of hydrocarbons contaminated sites, proving to be better than the chemical surfactants in many
aspects including degradability (Sammarco et al. 2013; Matvyeyeva et al. 2014).
Serratia marcescens, which is a gram-negative bacillus, belonging to Enterobacteriaceae, is better known for the production of red pigment prodigiosin and biosurfactant
serrawettin (Muthukumar et al. 2016; Sunaga et al. 2016). At the time when the cell
growth rate is sluggish under unfavourable conditions, the pigment biosynthesis has a
role of being the protective mechanism (Li et al. 2005). Serratia produces chitinolytic
enzymes that have a practical part in the biological degradation of chitin (Someya
et al. 2000) and its related environmental applications along with environmental
protection (Brzezinska et al. 2014). Biosurfactants with the current light of focus are
the potent tool for developing a sustainable environment. This study accounts for
V. Vijayalekshmi et al.
1 Introduction
Biosurfactants refer to any biomolecules which exhibit characteristics like surfaceactive and are found to be amphipathic in nature, which can be produced extracellularly by various microbes including bacteria, fungi and yeasts. They form aggregates at the interfaces amid different fluid polarities, wherein decreasing the surface
(Saravanan and Vijayakumar 2012). The unique features of microbial surfactants
include biodegradability, emulsifying and demulsifying ability, wetting and penetrating agents, tolerance to temperature, pH, ionic strength, low toxicity and viscosity
reducing agents make them most suitable for remediation of environmental contamination, environmental safety (Akbari et al. 2018) and finds application in food,
pharmaceutical and allied industries (Shekhar et al. 2015; Sharma et al. 2018). Oil
spills and various other hydrocarbon contaminants in the soil and aquatic environment is becoming a significant focus of attention in the today world. Absorbents and
synthetic organic products like lime, plastic polymers and cellulose-based materials,
polyurethane foams, polypropylene and elastomers were preferred as the commercial
sorbents in the oil spill cleanup considering the properties of good hydrophobicity,
uptake capacity and oil recovery (Adebajo et al. 2003; Seo et al. 2018), but then it
faced the problems of low degradability comparing to the naturally occurring mineral
and vegetable products (Teas et al. 2001). Such disadvantages has to be mitigated via
microbialy generated surfactants. Microorganisms exposed to oil-contaminated sites,
develop the potential to harness hydrocarbons as carbon and energy for its metabolic
activities. Biosurfactants increase the substrate bioavailability for microorganisms
and interacts with the cell surface, thereby increasing the surface hydrophobicity,
thus allowing substrates to accumulate faster within the bacterial cells (Liu et al.
2017). In comparison with its chemical counterparts, biosurfactants are very particular, potent and competent under an extensive range of oil and receptacle environment and may only require meagre quantities. Because of these attributes, they are
preferred in different industrial processes and physicochemical phenomena, wherein
they attribute enhanced solubility, increased mobility (Pacwa-Płociniczak et al. 2011;
Rufino et al. 2014). Microbial biosurfactant with all these unique properties is considered to be a best green alternative potent source when comparing to other methods
for clearing oil spills and plays a promising role in bioremediation of hydrocarbons contaminated sites, proving to be better than the chemical surfactants in many
aspects including degradability (Sammarco et al. 2013; Matvyeyeva et al. 2014).
Serratia marcescens, which is a gram-negative bacillus, belonging to Enterobacteriaceae, is better known for the production of red pigment prodigiosin and biosurfactant
serrawettin (Muthukumar et al. 2016; Sunaga et al. 2016). At the time when the cell
growth rate is sluggish under unfavourable conditions, the pigment biosynthesis has a
role of being the protective mechanism (Li et al. 2005). Serratia produces chitinolytic
enzymes that have a practical part in the biological degradation of chitin (Someya
et al. 2000) and its related environmental applications along with environmental
protection (Brzezinska et al. 2014). Biosurfactants with the current light of focus are
the potent tool for developing a sustainable environment. This study accounts for