94
as a production host (Wang et al. 2005). Punt et al. (2002) reported that A. niger is
commercially used in the food industry and classified as a group of GRAS (generally recognized as safe) in accordance with the Food and Drug Administration
(FDA). As shown in Table 6.4, A. niger can produce multiple enzymes such as pectinase, lipase, glucose oxidase, lactase, pentosanase, proteases, β-glucanase, cellulase, glucoamylase, and α-amylase.
Different approaches were used in order to optimize the application of these filamentous fungi including from the molecular part and also biotransformation. In a
previous research from Miyazaki et al. (2011), a gene for processing the
α-glucosidase I from the Aspergillus brasiliensis ATCC 9642 for heterologous
expression of fusion enzyme hydrolyzed pyridylaminated (PA) oligosaccharides
Glc3Man9GlcNAc2-PA and Glc3Man4-PA. This fusion enzyme is an oligosaccharide precursor of eukaryotic N-linked glycoproteins and processing α-glucosidase
I. Besides, Abas et al. (2010) studied the effect on the biotransformation of (R)-1(4- bromo-phenyl)-ethanol by using the Aspergillus niger as biocatalyst. The usage
of Aspergillus niger as biocatalyst in the studies is due to the simple function of
asymmetric reduction of enzyme 1-(4-bromo-phenyl)-ethanone to (R)-1-(4-bromophenyl)-ethanol through the optimized condition that influenced the
bioconversion.
With regard to the capability of fungal applications in many industrial processes,
fungal is very much desired for the production of the enzyme pectinases. There are
many studies that have been reported for the efficiency of fungal used as biofactories for pectinase production. Ahmed et al. (2016) reported the production of pectinase by Aspergillus niger using citrus waste peel. The maximum enzyme yield of
117.1 mM/mL/min was obtained in an orange waste peel medium and optimally
active at pH ¼ 7 and 55 °C. Another study by El-Enshasy et al. (2018) reported the
bioprocess optimization for pectinase production using Aspergillus niger. They
found that the enzyme production was able to be produced up to 450 U/mL after
126 h cultivation time in submerged cultivation using fed-batch strategy in a bioreactor. A recent study conducted by Mehmood et al. (2019) showed maximum pectinase production of 480.45 U/mL within a period of 1-day cultivation under
solid-state fermentation. The production of pectinase is high and within a short
period of time; however, it required further study in terms of large-scale production
using solid stage cultivation strategy.
6.3.2 D-Galacturonic Acid Degradation Pathway
It is well known that D-galacturonic acid is the main constituent of pectin. It also is
a natural and plentiful component of polysaccharides and can also serve as a pivotal
carbon source for microbes (Zhang et al. 2011). There are two types of backbones
present in pectin which are homogalacturonan (smooth region) and rhamnogalacturonan I (hairy region). Homogalacturonan consists of α-1,4-linked D-galacturonic
acid, whereas rhamnogalacturonan I comprises alternating α-1,4 linked
H. Suhaimi et al.
as a production host (Wang et al. 2005). Punt et al. (2002) reported that A. niger is
commercially used in the food industry and classified as a group of GRAS (generally recognized as safe) in accordance with the Food and Drug Administration
(FDA). As shown in Table 6.4, A. niger can produce multiple enzymes such as pectinase, lipase, glucose oxidase, lactase, pentosanase, proteases, β-glucanase, cellulase, glucoamylase, and α-amylase.
Different approaches were used in order to optimize the application of these filamentous fungi including from the molecular part and also biotransformation. In a
previous research from Miyazaki et al. (2011), a gene for processing the
α-glucosidase I from the Aspergillus brasiliensis ATCC 9642 for heterologous
expression of fusion enzyme hydrolyzed pyridylaminated (PA) oligosaccharides
Glc3Man9GlcNAc2-PA and Glc3Man4-PA. This fusion enzyme is an oligosaccharide precursor of eukaryotic N-linked glycoproteins and processing α-glucosidase
I. Besides, Abas et al. (2010) studied the effect on the biotransformation of (R)-1(4- bromo-phenyl)-ethanol by using the Aspergillus niger as biocatalyst. The usage
of Aspergillus niger as biocatalyst in the studies is due to the simple function of
asymmetric reduction of enzyme 1-(4-bromo-phenyl)-ethanone to (R)-1-(4-bromophenyl)-ethanol through the optimized condition that influenced the
bioconversion.
With regard to the capability of fungal applications in many industrial processes,
fungal is very much desired for the production of the enzyme pectinases. There are
many studies that have been reported for the efficiency of fungal used as biofactories for pectinase production. Ahmed et al. (2016) reported the production of pectinase by Aspergillus niger using citrus waste peel. The maximum enzyme yield of
117.1 mM/mL/min was obtained in an orange waste peel medium and optimally
active at pH ¼ 7 and 55 °C. Another study by El-Enshasy et al. (2018) reported the
bioprocess optimization for pectinase production using Aspergillus niger. They
found that the enzyme production was able to be produced up to 450 U/mL after
126 h cultivation time in submerged cultivation using fed-batch strategy in a bioreactor. A recent study conducted by Mehmood et al. (2019) showed maximum pectinase production of 480.45 U/mL within a period of 1-day cultivation under
solid-state fermentation. The production of pectinase is high and within a short
period of time; however, it required further study in terms of large-scale production
using solid stage cultivation strategy.
6.3.2 D-Galacturonic Acid Degradation Pathway
It is well known that D-galacturonic acid is the main constituent of pectin. It also is
a natural and plentiful component of polysaccharides and can also serve as a pivotal
carbon source for microbes (Zhang et al. 2011). There are two types of backbones
present in pectin which are homogalacturonan (smooth region) and rhamnogalacturonan I (hairy region). Homogalacturonan consists of α-1,4-linked D-galacturonic
acid, whereas rhamnogalacturonan I comprises alternating α-1,4 linked
H. Suhaimi et al.