proteases of alkaliphiles are desirable in detergent formulation. The alkaline active
proteases used in detergent formulation are those which are non-specific serine
proteases capable of cleaving most peptide bonds. Unlike serine proteases, cysteine
(thiol) proteases and metalloproteases cannot be used in detergent formulation.
These proteases can be inactivated by the detergent bleaching agents which oxidize
cysteine proteases and chelators that strip the metal cofactor of metalloproteases.
Thus, the focus has always been on serine proteases. Since Novo Nordisk developed
Alcalase (from Bacillus licheniformis), the first alkaline active detergent protease in
1958, several serine proteases have been developed and implemented in detergent
formulation. The alkaline active Esperase and Maxtase (from alkaliphilic strains of
Bacillus licheniformis) and Savinase (from alkaliphilic B. amyloliquefaciens) are
among the well-known examples of commercial detergent proteases. In recent years,
alkaline active proteases from Bacillus cereus, Bacillus pumilus strain CBS, Streptomyces sp. strain AB1, Bacillus licheniformis, Aspergillus flavus, Bacillus brevis,
and Bacillus subtilis AG-1 have exhibited excellent detergent compatibility [64].
Like protein-based dirt, lipid-containing dirt is an important target in cleaning.
Alkaline active lipases which are compatible to detergent ingredients such as
chelators, surfactants, and oxidants have become vital detergent enzymes. Nearly
5% of the world phosphate produced globally had been used in detergent formulation which in addition to reducing water hardness helps to remove fatty and greasy
dirt. However, due to environmental concern, there is a need to limit or avoid
phosphate in detergent formulations [65]. This led to an increase in the need for
lipases that degrade and remove fat-containing dirt in non-phosphate detergents.
This demand has brought screening of several alkaliphiles from which a range of
interesting lipases have been reported [66–68].
It is not only dirt-degrading enzymes that are considered to used in detergent
formulation, enzymes which modify the surface of textiles have also been considered. An interesting approach in this regard could be the introduction of alkaline
active cellulases as detergent enzymes for washing cotton fabrics [69]. Unlike other
detergent enzymes, cellulases in detergents do not directly hydrolyze the dirt, but it
modifies the fabric surface and facilitates the dirt removal. Garments made from
cellulose fabric over time tend to have small fibers on its surface which in addition to
reducing the color intensity can easily attach to dirt. These small fibers are mostly
amorphous in structure and hence are susceptible to enzymatic hydrolysis. Thus,
cellulases intended for this application should remain operationally stable in the
detergent/washing condition and degrade the fine cellulose fibers but are inert toward
the main crystalline cellulose fibers of the garment. The hydrolysis of the fine fibers
from the surface of the garment removes the dirt attached to these fibers and
enhances the brightness to its “new” condition [70].
In its journey of over 100 years, detergent enzymes have astonishingly progressed
and revolutionized the entire detergent industry. However, there are still some issues
that deserve a proper look. Although detergent enzymes have been in the market for
a long time, it is not yet readily available in most developing countries. So far, the
application seems restricted in the developed world. The main limiting factors that
contribute to low usage of detergent enzymes in many third-world countries seem to
12
G. Mamo and B. Mattiasson
proteases used in detergent formulation are those which are non-specific serine
proteases capable of cleaving most peptide bonds. Unlike serine proteases, cysteine
(thiol) proteases and metalloproteases cannot be used in detergent formulation.
These proteases can be inactivated by the detergent bleaching agents which oxidize
cysteine proteases and chelators that strip the metal cofactor of metalloproteases.
Thus, the focus has always been on serine proteases. Since Novo Nordisk developed
Alcalase (from Bacillus licheniformis), the first alkaline active detergent protease in
1958, several serine proteases have been developed and implemented in detergent
formulation. The alkaline active Esperase and Maxtase (from alkaliphilic strains of
Bacillus licheniformis) and Savinase (from alkaliphilic B. amyloliquefaciens) are
among the well-known examples of commercial detergent proteases. In recent years,
alkaline active proteases from Bacillus cereus, Bacillus pumilus strain CBS, Streptomyces sp. strain AB1, Bacillus licheniformis, Aspergillus flavus, Bacillus brevis,
and Bacillus subtilis AG-1 have exhibited excellent detergent compatibility [64].
Like protein-based dirt, lipid-containing dirt is an important target in cleaning.
Alkaline active lipases which are compatible to detergent ingredients such as
chelators, surfactants, and oxidants have become vital detergent enzymes. Nearly
5% of the world phosphate produced globally had been used in detergent formulation which in addition to reducing water hardness helps to remove fatty and greasy
dirt. However, due to environmental concern, there is a need to limit or avoid
phosphate in detergent formulations [65]. This led to an increase in the need for
lipases that degrade and remove fat-containing dirt in non-phosphate detergents.
This demand has brought screening of several alkaliphiles from which a range of
interesting lipases have been reported [66–68].
It is not only dirt-degrading enzymes that are considered to used in detergent
formulation, enzymes which modify the surface of textiles have also been considered. An interesting approach in this regard could be the introduction of alkaline
active cellulases as detergent enzymes for washing cotton fabrics [69]. Unlike other
detergent enzymes, cellulases in detergents do not directly hydrolyze the dirt, but it
modifies the fabric surface and facilitates the dirt removal. Garments made from
cellulose fabric over time tend to have small fibers on its surface which in addition to
reducing the color intensity can easily attach to dirt. These small fibers are mostly
amorphous in structure and hence are susceptible to enzymatic hydrolysis. Thus,
cellulases intended for this application should remain operationally stable in the
detergent/washing condition and degrade the fine cellulose fibers but are inert toward
the main crystalline cellulose fibers of the garment. The hydrolysis of the fine fibers
from the surface of the garment removes the dirt attached to these fibers and
enhances the brightness to its “new” condition [70].
In its journey of over 100 years, detergent enzymes have astonishingly progressed
and revolutionized the entire detergent industry. However, there are still some issues
that deserve a proper look. Although detergent enzymes have been in the market for
a long time, it is not yet readily available in most developing countries. So far, the
application seems restricted in the developed world. The main limiting factors that
contribute to low usage of detergent enzymes in many third-world countries seem to
12
G. Mamo and B. Mattiasson