are generally used for the isolation of biosurfactant-producing microbes (Giani
et al. 1997). It may be possible that the biosurfactant-producing microbial
populations are present in the collected sample that is not enriched by the applied
enrichment media (Bodour et al. 2003).
4.3 Screening Methods
Different methods are used for the screening of biosurfactant efficiency such as oil
spreading test, hemolysis test, emulsification index, drop collapse method, blue agar
plate method, and hydrocarbon overlay agar method (Samanta et al. 2012). Also,
nowadays, computational modeling and structured screenings are used for the
development of biosurfactants with high-value properties, and these factors play a
crucial role in future research (Zhao et al. 2016).
4.4 Raw Materials for Biosurfactant Production
Several cheap waste materials have been used as substrates for biosurfactant production, thus bringing cost-effectiveness with much-needed waste management
(Satpute et al. 2017). The use of industrial waste as a substrate for the production
of biosurfactant in recent times paved the way not only for a cost-effective production process but also in establishing a sustainable and clean environment regarding
the waste generated (Patil and Rao 2015).
Olive oil mill effluent (OOME) is a concentrated black liquor with a watersoluble portion of ripe olives and water used for the extraction of olive oil. OOME
has polyphenols that cause adverse effects when disposed to the environment.
However, it also contains sugars (20–80 gL
À1 ), nitrogen compounds
(12–24 gL
À1 ), organic acids (5–15 gL
À1 ), and residual oil (0.3–5 gL
À1 ) (Santos
et al. 2016a). Molasses is a by-product of beet and sugarcane processing, which are
rich sole of carbon source. The high sugar content (48–56%) makes molasses the
first choice for biosurfactant production. Joshi et al. (2008) used molasses to produce
biosurfactants from strains of Bacillus. The dairy industry provides a different type
of whey, such as whey waste, curd whey, lactic whey, and cheese whey. Lactic whey
contains a high amount of lactose (approximately 75%). Whey disposal causes
pollution problems, especially in countries that depend on a dairy economy
(Helmy et al. 2011). Starchy waste was obtained from the potato processing industry. In addition to 80% water content, potato waste has fats (0.1%), carbohydrates
(17%), and proteins (2%) and also trace elements, vitamins, and inorganic minerals
(Helmy et al. 2011).
Meat processing industries are the major source of animal fat and tallow. Due to
the lower degree of harm to health, vegetable oils gain a large part of the market than
12
K. Mulugeta et al.
et al. 1997). It may be possible that the biosurfactant-producing microbial
populations are present in the collected sample that is not enriched by the applied
enrichment media (Bodour et al. 2003).
4.3 Screening Methods
Different methods are used for the screening of biosurfactant efficiency such as oil
spreading test, hemolysis test, emulsification index, drop collapse method, blue agar
plate method, and hydrocarbon overlay agar method (Samanta et al. 2012). Also,
nowadays, computational modeling and structured screenings are used for the
development of biosurfactants with high-value properties, and these factors play a
crucial role in future research (Zhao et al. 2016).
4.4 Raw Materials for Biosurfactant Production
Several cheap waste materials have been used as substrates for biosurfactant production, thus bringing cost-effectiveness with much-needed waste management
(Satpute et al. 2017). The use of industrial waste as a substrate for the production
of biosurfactant in recent times paved the way not only for a cost-effective production process but also in establishing a sustainable and clean environment regarding
the waste generated (Patil and Rao 2015).
Olive oil mill effluent (OOME) is a concentrated black liquor with a watersoluble portion of ripe olives and water used for the extraction of olive oil. OOME
has polyphenols that cause adverse effects when disposed to the environment.
However, it also contains sugars (20–80 gL
À1 ), nitrogen compounds
(12–24 gL
À1 ), organic acids (5–15 gL
À1 ), and residual oil (0.3–5 gL
À1 ) (Santos
et al. 2016a). Molasses is a by-product of beet and sugarcane processing, which are
rich sole of carbon source. The high sugar content (48–56%) makes molasses the
first choice for biosurfactant production. Joshi et al. (2008) used molasses to produce
biosurfactants from strains of Bacillus. The dairy industry provides a different type
of whey, such as whey waste, curd whey, lactic whey, and cheese whey. Lactic whey
contains a high amount of lactose (approximately 75%). Whey disposal causes
pollution problems, especially in countries that depend on a dairy economy
(Helmy et al. 2011). Starchy waste was obtained from the potato processing industry. In addition to 80% water content, potato waste has fats (0.1%), carbohydrates
(17%), and proteins (2%) and also trace elements, vitamins, and inorganic minerals
(Helmy et al. 2011).
Meat processing industries are the major source of animal fat and tallow. Due to
the lower degree of harm to health, vegetable oils gain a large part of the market than
12
K. Mulugeta et al.