5 Biosurfactants
There is a widespread concern about accumulation of chemically synthetized surfactants in different environments, suggesting an immediate need for biodegradable
surfactants. Although there are many known biodegradable surfactants, they are far
expensive than the chemical surfactants driven from petrochemicals, and this limits
their application. Many biosurfactant candidates with suitable ionic and dissolving
properties exist from a multitude of microbial sources. Thus, it is important to
produce these biodegradable surfactants at competitive price. First attempts for
genetically modified super bio-producers have been made. Moreover, the development of fermentation processes that use waste materials is undergoing. It is evident
that prices of biosurfactants will go down when the production volumes will grow.
Surfactants used in detergent formulations are released into the environment by
the wastewater pathway. It may be possible to recover such surfactants from
wastewater. However, as far as the authors know, attempts to recover any surfactants
back from wastewaters have not been tried. It is probably advantageous if
the spectrum of surfactant structures in wastewaters is heterogenic. The European
Detergent Regulation 684/004 (https://eur-lex.europa.eu/eli/reg/2004/648/oj)
demands that all types of commercially available surfactants must be ultimately
biodegradable under aerobic conditions which is one of the most important mechanisms for removal of chemicals released into the environment. Half of the
total surfactant consumption belongs to household applications, which is the largest
market for surfactants. Anaerobic biodegradability is not required so far, with
exception of eco-labeled products. Although the natural environment is predominately aerobic, there are some more or less strict anaerobic compartments such as
river sediments, subsurface soil layer, and anaerobic sludge digesters of wastewater
treatment plants. In this environment, anaerobic biodegradation may contribute
to avoid accumulation of anthropogenic chemicals [24]. All biosurfactants are
surface-active compounds and are synthetized by microbes such as bacteria, fungi,
and yeasts. Biosurfactants are classified to low-molecular-weight (usually
500–1,500 Da) agents and high-molecular-weight agents called bio-emulsifiers.
These two groups are further divided into subgroups based on their components,
like glycolipids, lipoproteins, phospholipids, etc. Undoubtedly, biosurfactants are
produced by a wide range of organisms, but microbial sources are the most promising for large-scale production.
Biosurfactants are of major commercial interest, and they can have a critical
micelle concentration (CMC) even distinctly lower than those of the chemical
surfactants. Normally, biosurfactants are nontoxic and harmless to the environment
because they degrade quickly in the nature. They have large diversity and exhibit a
variety of properties and are therefore flexible, and a suitable agent can be found to
any application in concern. Properties, structures, and applications of biosurfactants
are extensively summarized with illustrative introduction to the micellar structures
by Santos et al. [25].
Metabolites Produced by Alkaliphiles with Potential Biotechnological. . .
169
There is a widespread concern about accumulation of chemically synthetized surfactants in different environments, suggesting an immediate need for biodegradable
surfactants. Although there are many known biodegradable surfactants, they are far
expensive than the chemical surfactants driven from petrochemicals, and this limits
their application. Many biosurfactant candidates with suitable ionic and dissolving
properties exist from a multitude of microbial sources. Thus, it is important to
produce these biodegradable surfactants at competitive price. First attempts for
genetically modified super bio-producers have been made. Moreover, the development of fermentation processes that use waste materials is undergoing. It is evident
that prices of biosurfactants will go down when the production volumes will grow.
Surfactants used in detergent formulations are released into the environment by
the wastewater pathway. It may be possible to recover such surfactants from
wastewater. However, as far as the authors know, attempts to recover any surfactants
back from wastewaters have not been tried. It is probably advantageous if
the spectrum of surfactant structures in wastewaters is heterogenic. The European
Detergent Regulation 684/004 (https://eur-lex.europa.eu/eli/reg/2004/648/oj)
demands that all types of commercially available surfactants must be ultimately
biodegradable under aerobic conditions which is one of the most important mechanisms for removal of chemicals released into the environment. Half of the
total surfactant consumption belongs to household applications, which is the largest
market for surfactants. Anaerobic biodegradability is not required so far, with
exception of eco-labeled products. Although the natural environment is predominately aerobic, there are some more or less strict anaerobic compartments such as
river sediments, subsurface soil layer, and anaerobic sludge digesters of wastewater
treatment plants. In this environment, anaerobic biodegradation may contribute
to avoid accumulation of anthropogenic chemicals [24]. All biosurfactants are
surface-active compounds and are synthetized by microbes such as bacteria, fungi,
and yeasts. Biosurfactants are classified to low-molecular-weight (usually
500–1,500 Da) agents and high-molecular-weight agents called bio-emulsifiers.
These two groups are further divided into subgroups based on their components,
like glycolipids, lipoproteins, phospholipids, etc. Undoubtedly, biosurfactants are
produced by a wide range of organisms, but microbial sources are the most promising for large-scale production.
Biosurfactants are of major commercial interest, and they can have a critical
micelle concentration (CMC) even distinctly lower than those of the chemical
surfactants. Normally, biosurfactants are nontoxic and harmless to the environment
because they degrade quickly in the nature. They have large diversity and exhibit a
variety of properties and are therefore flexible, and a suitable agent can be found to
any application in concern. Properties, structures, and applications of biosurfactants
are extensively summarized with illustrative introduction to the micellar structures
by Santos et al. [25].
Metabolites Produced by Alkaliphiles with Potential Biotechnological. . .
169