**3. Delignification**

The delignification process involves at least 3 types of enzymes, namely: lignin peroxidase, manganese peroxidase, and *lacase* [9]. Lignin peroxidase and manganese peroxidase are enzymes that depend on hydrogen peroxide. In the delignification process, there are at least four mechanisms carried out by the enzyme, namely: breaking ether bonds between monomers; cutting propane side chains; de-methylation; cleans benzene bonds to ketoadipic acid to enter the TCA cycle [10, 11],

**Figure 2** shows the delignification process by the lignin peroxidase (LiP) enzyme. This enzyme is an enzyme that depends on the availability of hydrogen peroxide.

#### **Figure 2.**

*LiP enzyme delignification mechanism [12].*

#### **Figure 3.** *MnP enzyme delignification mechanism [12].*

This enzyme will change the 1- (3,4-dimethoxyphenyl) -2- (2-methoxyphenoxy) -1,3 dihydroxypropane group into a radical cation so that it is less stable and causes the breaking of the bond to become a 3,4-dimethoxy-benzaldehyde compound [12].

**Figure 3** shows the working process of the Manganese Peroxidase (MnP) enzyme. This enzyme is an enzyme that depends on the availability of Mn2 + ions. This enzyme works by converting 1- (3,5-dimethoxy-4-hydroxyphenyl) -2- (4- (hydroxymethyl) -2-methoxyphenoxy) -1,3-dihydroxypropane into radical phenolic compounds so that it is unstable which causes its formation compounds such as 2,6-dimethoxy-1,4-dihydroxybenzene.

**Figure 4** shows the action of the laccase enzyme. This laccase enzyme directly converts phenolic compounds into simpler compounds without going through intermediates. This process can go through 3 pathways, namely: cleavage of C alpha and beta, addition of alkyl groups, and C alpha oxidation.

**133**

**Figure 5.**

**Figure 4.**

*The Nanocellulose Fibers from Symbiotic Culture of Bacteria and Yeast (SCOBY) Kombucha...*

**4. Cellulose in symbiotic culture of bacteria and yeast (SCOBY)**

*Synthesis mechanism of cellulose I and cellulose II by* Acetobacter xylinum *[16].*

Symbiotic Culture of Bacteria and Yeast (SCOBY) is a cellulose biopolymer composed of the interaction of acetic acid bacteria and yeast. SCOBY can be formed through the kombucha fermentation process [13]. The cellulose formed in SCOBY has different characteristics with cellulose in plants. Cellulose that is synthesized through bacteria is considered more efficient and effective in the production process because it does not require a long time and a large amount of substrate [14]. Some of the advantages of producing cellulose from bacteria compared to plants include high purity, better mechanical strength, a higher polymerization rate and crystallinity index [15], a higher tensile strength based on a tensile test and a better hydrophobicity ability to water [16]. Bacterial cellulose has a basic structure of microfibrils with a glucan chain arrangement that is bound by hydrogen bonds to form a crystalline domain. Microfibrils in cellulose synthesized by bacteria are known to have a size 100 times smaller than plant cellulose fibers [17]. Electron microscopy observations show that the cellulose produced by bacteria will be synthesized in the form of cellulose fibers. Acetic acid bacteria produce two forms of cellulose, namely cellulose I in the form of a ribbon-like polymer and cellulose II in the form of an amorphous polymer which is more stable. The difference in the synthesis of cellulose I and II is in the process of forming cellulose outside the cytoplasmic membrane (**Figure 5**).

*DOI: http://dx.doi.org/10.5772/intechopen.96310*

*The mechanism of delignification of the laccase enzyme [12].*

*The Nanocellulose Fibers from Symbiotic Culture of Bacteria and Yeast (SCOBY) Kombucha... DOI: http://dx.doi.org/10.5772/intechopen.96310*

**Figure 4.**

*Nanofibers - Synthesis, Properties and Applications*

This enzyme will change the 1- (3,4-dimethoxyphenyl) -2- (2-methoxyphenoxy) -1,3 dihydroxypropane group into a radical cation so that it is less stable and causes the breaking of the bond to become a 3,4-dimethoxy-benzaldehyde compound [12]. **Figure 3** shows the working process of the Manganese Peroxidase (MnP) enzyme. This enzyme is an enzyme that depends on the availability of Mn2 + ions. This enzyme works by converting 1- (3,5-dimethoxy-4-hydroxyphenyl) -2- (4- (hydroxymethyl) -2-methoxyphenoxy) -1,3-dihydroxypropane into radical phenolic compounds so that it is unstable which causes its formation compounds

**Figure 4** shows the action of the laccase enzyme. This laccase enzyme directly converts phenolic compounds into simpler compounds without going through intermediates. This process can go through 3 pathways, namely: cleavage of C alpha

such as 2,6-dimethoxy-1,4-dihydroxybenzene.

*MnP enzyme delignification mechanism [12].*

and beta, addition of alkyl groups, and C alpha oxidation.

**132**

**Figure 3.**

**Figure 2.**

*LiP enzyme delignification mechanism [12].*

*The mechanism of delignification of the laccase enzyme [12].*
