Bacillus sp. S-1 [35, 36], Micrococcus sp. Y-1 [35], Bacillus sp. KSM-1876 [37],
amylopullulanase from Bacillus sp. KSM-1378 [38], neopullulanase from Bacillus
sp. KSM-1876 [39] and an isoamylase of alkaliphilic Bacillus sp. KSM-3309 [40].
The demand for amylases with high specific activity and activity at alkaline
conditions for the detergent industry has prompted the engineering of existing
enzymes to produce enzymes with the desired properties. Genes encoding wildtype and mutant Bacillus amyloliquefaciens amylase (BAA) were subjected to
error-prone PCR and gene shuffling. One of the mutants resulted in a fivefold higher
activity at pH 10, thus producing a more suitable enzyme for application in
the detergent industry [41].
4.2 Production of Maltoligosaccharides
Maltoligosaccharides is a generic term that is used to refer to saccharides derived
from glucose, with a degree of polymerization of two to ten glucose residues.
The composition of saccharides obtained after starch hydrolysis is highly dependent
on the effect of temperature, the conditions of hydrolysis and the origin of enzyme,
enzyme properties such as substrate specificity, thermostability and pH optimum
[12]. The discovery of microbial enzymes that produce specific oligosaccharides
such as maltotriose, maltotetraose, maltopentaose and maltohexaose has made
possible the manufacture of syrups with high content of each maltooligosaccharide.
These syrups are prepared from liquefied starch using the specific enzyme in
combination with a debranching enzyme, such as pullulanase or isoamylase.
Such syrups have low sweetness, provide resistance to retrogradation of starch
gels and prevent crystallization of sucrose. These products are now used in powdering materials (fillers), saccharides for dry milk, flavour enhancers for various foods,
liquid diets for patients and viscosity-increasing agents in the food, beverage,
cosmetic, pharmaceutical and fine chemicals industries [42].
There are various reports of alkaline-active maltooligosaccharide-forming
amylases in the literature. These vary in the composition of the saccharides
formed, which is dependent on the substrate used and the hydrolysis conditions.
For instance, Amy 34, a maltohexaose-forming amylase from Bacillus halodurans
LBK 34, produced maltohexaose as the main initial product of starch hydrolysis,
while the major product formed from amylose, amylopectin and maltodextrin
was maltotetraose [43]. Other maltooligosaccharide-forming amylases that have
been described from alkaliphiles include the maltotetraose-forming alkaline
α-amylase from an alkaliphilic Bacillus strain GM8901 [44], maltopentaose-forming
amylase from Bacillus sp. TS-23 [30], maltohexaose-forming amylases from
alkaliphilic Bacillus sp. H-167 [45, 46], Bacillus sp. 707 [47], maltohexaose and
maltoheptaose-forming amylase from Alcaligenes latus D2271 [42], wherein it is
reported that it is feasible to increase the yield of maltohexaose and maltoheptaose
by the enzyme when the debranching enzymes pullulanases and isoamylases
are included during the hydrolysis. Examples of alkaliphilic Bacillus species that
produce maltooligosaccharides are summarized in Table 1. Majority of these
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amylopullulanase from Bacillus sp. KSM-1378 [38], neopullulanase from Bacillus
sp. KSM-1876 [39] and an isoamylase of alkaliphilic Bacillus sp. KSM-3309 [40].
The demand for amylases with high specific activity and activity at alkaline
conditions for the detergent industry has prompted the engineering of existing
enzymes to produce enzymes with the desired properties. Genes encoding wildtype and mutant Bacillus amyloliquefaciens amylase (BAA) were subjected to
error-prone PCR and gene shuffling. One of the mutants resulted in a fivefold higher
activity at pH 10, thus producing a more suitable enzyme for application in
the detergent industry [41].
4.2 Production of Maltoligosaccharides
Maltoligosaccharides is a generic term that is used to refer to saccharides derived
from glucose, with a degree of polymerization of two to ten glucose residues.
The composition of saccharides obtained after starch hydrolysis is highly dependent
on the effect of temperature, the conditions of hydrolysis and the origin of enzyme,
enzyme properties such as substrate specificity, thermostability and pH optimum
[12]. The discovery of microbial enzymes that produce specific oligosaccharides
such as maltotriose, maltotetraose, maltopentaose and maltohexaose has made
possible the manufacture of syrups with high content of each maltooligosaccharide.
These syrups are prepared from liquefied starch using the specific enzyme in
combination with a debranching enzyme, such as pullulanase or isoamylase.
Such syrups have low sweetness, provide resistance to retrogradation of starch
gels and prevent crystallization of sucrose. These products are now used in powdering materials (fillers), saccharides for dry milk, flavour enhancers for various foods,
liquid diets for patients and viscosity-increasing agents in the food, beverage,
cosmetic, pharmaceutical and fine chemicals industries [42].
There are various reports of alkaline-active maltooligosaccharide-forming
amylases in the literature. These vary in the composition of the saccharides
formed, which is dependent on the substrate used and the hydrolysis conditions.
For instance, Amy 34, a maltohexaose-forming amylase from Bacillus halodurans
LBK 34, produced maltohexaose as the main initial product of starch hydrolysis,
while the major product formed from amylose, amylopectin and maltodextrin
was maltotetraose [43]. Other maltooligosaccharide-forming amylases that have
been described from alkaliphiles include the maltotetraose-forming alkaline
α-amylase from an alkaliphilic Bacillus strain GM8901 [44], maltopentaose-forming
amylase from Bacillus sp. TS-23 [30], maltohexaose-forming amylases from
alkaliphilic Bacillus sp. H-167 [45, 46], Bacillus sp. 707 [47], maltohexaose and
maltoheptaose-forming amylase from Alcaligenes latus D2271 [42], wherein it is
reported that it is feasible to increase the yield of maltohexaose and maltoheptaose
by the enzyme when the debranching enzymes pullulanases and isoamylases
are included during the hydrolysis. Examples of alkaliphilic Bacillus species that
produce maltooligosaccharides are summarized in Table 1. Majority of these
228
S. O. Hashim