2017). The costs of processing/purification, raw materials, and low yields negatively impacted the production process. The cost of the raw materials accounts for
30% of the total production cost (Ahmad et al. 2016).
Hence, the microbial biosurfactants are a better alternative for the synthetic
surfactants; there is a need to understand them for the effective use in different
applications. The review highlights the informations about the microbial-based
biosurfactants. More specifically, an overview of the physical and chemical properties, classification, source, production, characterization, and its applications is
summarized.
2 Physical and Chemical Properties of Biosurfactants
2.1 Surface and Interface Activity
Surfactant has the ability in reducing surface tension and the interfacial tension, i.e.,
surface tension of the water is reduced from 72.75 mNm
À1 to 35 mNm
À1 (at 20
C)
and interfacial tension of water from 40 to 1 mNm
À1 with the added surfactant.
Surfactin produced from B. subtilis decreased the surface tension of water to
25 mNm
À1 and interfacial tension of water to less than 1 mNm
À1 . Pseudomonas
aeruginosa produces rhamnolipid biosurfactants that reduced the water surface
tension more effectively than many other known surfactants (Kim et al. 2015).
The relationship between surface tension, biosurfactant concentration, and formation
of micelles is depicted in Fig. 1.1.
2.2 Tolerance, Toxicity, and Biodegradability
Most of the biosurfactants and their surface activity can resist environmental
factors, such as temperature, pH, and salt. The biosurfactant produced by
Arthrobacter protophormiae is stable at a temperature of (30–100
C) and pH
(2–12) (Singh and Cameotra 2004). Lipopeptides, which are produced by Bacillus
subtilis, are stable at NaCl concentrations of >15% and pH range of 4–12 (Cheng
et al. 2016). Mutagenicity and toxicity of biosurfactants (Pseudomonas
aeruginosa), when contrasted with that of synthetic surfactants, advocated the
biosurfactant’s least effects on this context (Flasz et al. 1998; Shah et al. 2016).
Synthetic surfactants take more time to degrade than biosurfactants (Mohan et al.
2006). Rhamnolipid biosurfactants are readily biodegradable in both aerobic and
anaerobic conditions. Synthetic surfactant, for example, Triton X-100, is partially
biodegradable under aerobic conditions, and it does not degrade under anaerobic
conditions (Hirata et al. 2009).
6
K. Mulugeta et al.
30% of the total production cost (Ahmad et al. 2016).
Hence, the microbial biosurfactants are a better alternative for the synthetic
surfactants; there is a need to understand them for the effective use in different
applications. The review highlights the informations about the microbial-based
biosurfactants. More specifically, an overview of the physical and chemical properties, classification, source, production, characterization, and its applications is
summarized.
2 Physical and Chemical Properties of Biosurfactants
2.1 Surface and Interface Activity
Surfactant has the ability in reducing surface tension and the interfacial tension, i.e.,
surface tension of the water is reduced from 72.75 mNm
À1 to 35 mNm
À1 (at 20
C)
and interfacial tension of water from 40 to 1 mNm
À1 with the added surfactant.
Surfactin produced from B. subtilis decreased the surface tension of water to
25 mNm
À1 and interfacial tension of water to less than 1 mNm
À1 . Pseudomonas
aeruginosa produces rhamnolipid biosurfactants that reduced the water surface
tension more effectively than many other known surfactants (Kim et al. 2015).
The relationship between surface tension, biosurfactant concentration, and formation
of micelles is depicted in Fig. 1.1.
2.2 Tolerance, Toxicity, and Biodegradability
Most of the biosurfactants and their surface activity can resist environmental
factors, such as temperature, pH, and salt. The biosurfactant produced by
Arthrobacter protophormiae is stable at a temperature of (30–100
C) and pH
(2–12) (Singh and Cameotra 2004). Lipopeptides, which are produced by Bacillus
subtilis, are stable at NaCl concentrations of >15% and pH range of 4–12 (Cheng
et al. 2016). Mutagenicity and toxicity of biosurfactants (Pseudomonas
aeruginosa), when contrasted with that of synthetic surfactants, advocated the
biosurfactant’s least effects on this context (Flasz et al. 1998; Shah et al. 2016).
Synthetic surfactants take more time to degrade than biosurfactants (Mohan et al.
2006). Rhamnolipid biosurfactants are readily biodegradable in both aerobic and
anaerobic conditions. Synthetic surfactant, for example, Triton X-100, is partially
biodegradable under aerobic conditions, and it does not degrade under anaerobic
conditions (Hirata et al. 2009).
6
K. Mulugeta et al.