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Enhancement of Cellulose Degradation by Cattle Saliva.

Seki Y, Kikuchi Y, Kimura Y, Yoshimoto R, Takahashi M, Aburai K, Kanai Y, Ruike T, Iwabata K, Sugawara F, Sakai H, Abe M, Sakaguchi K - PLoS ONE (2015)

Bottom Line: Although cattle saliva, by itself, did not degrade cellulose, it enhanced the cellulase-catalyzed degradation of cellulose.Thus, the amount of reducing sugar produced increased approximately 2.9-fold by the addition of cattle saliva.We also found that non-enzymatic proteins, which were present in cattle saliva, were responsible for causing the enhancement effect.

View Article: PubMed Central - PubMed

Affiliation: Research Institute for Science and Technology, Tokyo University of Science, Noda, Chiba, Japan.

ABSTRACT
Saccharification of cellulose is a promising technique for producing alternative source of energy. However, the efficiency of conversion of cellulose into soluble sugar using any currently available methodology is too low for industrial application. Many additives, such as surfactants, have been shown to enhance the efficiency of cellulose-to-sugar conversion. In this study, we have examined first whether cattle saliva, as an additive, would enhance the cellulase-catalyzed hydrolysis of cellulose, and subsequently elucidated the mechanism by which cattle saliva enhanced this conversion. Although cattle saliva, by itself, did not degrade cellulose, it enhanced the cellulase-catalyzed degradation of cellulose. Thus, the amount of reducing sugar produced increased approximately 2.9-fold by the addition of cattle saliva. We also found that non-enzymatic proteins, which were present in cattle saliva, were responsible for causing the enhancement effect. Third, the mechanism of cattle saliva mediated enhancement of cellulase activity was probably similar to that of the canonical surfactants. Cattle saliva is available in large amounts easily and cheaply, and it can be used without further purification. Thus, cattle saliva could be a promising additive for efficient saccharification of cellulose on an industrial scale.

No MeSH data available.


Effect of various treatments on the enhancement effect of cattle saliva.(a) Denatured and dialyzed cattle saliva. Denaturation of cattle saliva: Cattle saliva was autoclaved for 13 minites at 121°C to denature proteins. After that, the saliva was centrifuged at 20,400 x g for 10 min. The supernatant (called ‘Autoclaved saliva’) was collected and subsequently used in experiments. Dialysis of cattle saliva: Cattle saliva was dialyzed against distilled water for 72 h at room temperture. The water was exchanged every other day. (b) Proteinase K treatment. Twenty microliters cattle saliva was mixed with 20 μL proteinase K (20 mg/mL) and the mixture was incubated at 50°C for 12 h. After the incubation, the mixture was incubated at 96°C for 10 min to denature proteinase K. This mixture was called ‘Proteinase K Saliva’ and used in the cellulose degradation assay. The concentration of cattle saliva in the reaction mixture was 5%. All experiments were performed in triplicate and average mean values were plotted. Error bars indicate ± standard deviations. Values labeled with asterisk are statistically different as established by Student's t-test (P < 0.05).
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pone.0138902.g003: Effect of various treatments on the enhancement effect of cattle saliva.(a) Denatured and dialyzed cattle saliva. Denaturation of cattle saliva: Cattle saliva was autoclaved for 13 minites at 121°C to denature proteins. After that, the saliva was centrifuged at 20,400 x g for 10 min. The supernatant (called ‘Autoclaved saliva’) was collected and subsequently used in experiments. Dialysis of cattle saliva: Cattle saliva was dialyzed against distilled water for 72 h at room temperture. The water was exchanged every other day. (b) Proteinase K treatment. Twenty microliters cattle saliva was mixed with 20 μL proteinase K (20 mg/mL) and the mixture was incubated at 50°C for 12 h. After the incubation, the mixture was incubated at 96°C for 10 min to denature proteinase K. This mixture was called ‘Proteinase K Saliva’ and used in the cellulose degradation assay. The concentration of cattle saliva in the reaction mixture was 5%. All experiments were performed in triplicate and average mean values were plotted. Error bars indicate ± standard deviations. Values labeled with asterisk are statistically different as established by Student's t-test (P < 0.05).

Mentions: We next attempted to identify the substance in the cattle saliva that was responsible for enhancing the degradation of cellulose. Cattle saliva contained many different types of minerals and organic substances, including sialic acid, mucin, lactoferrin, IGF-1, sodium bicarbonate, phosphoric salt and metal ions. In order to determine whether the substance is a small or a polymer molecule, we first dialyzed the cattle saliva and then used the dialyzed cattle saliva in the cellulose degradation assay. As shown in Fig 3A, we observed no significant difference between the amounts of reducing sugar produced using dialyzed cattle saliva and un-dialyzed cattle saliva. As the pore size of the dialysis membrane is 25–50 Å, only small molecules of sizes less than 14 kDa, such as sialic acid, IGF-1, sodium bicarbonate, phosphoric salt and metal ions, would diffuse across this membrane during dialysis. As a result, these small molecules are expected to be absent in the dialyzed cattle saliva. Thus, these small molecules in cattle saliva were not responsible for enhancing the enzymatic activity of cellulase. Incidentally, most of the polymer molecules known to be present in the cattle saliva are proteins and glycoproteins.


Enhancement of Cellulose Degradation by Cattle Saliva.

Seki Y, Kikuchi Y, Kimura Y, Yoshimoto R, Takahashi M, Aburai K, Kanai Y, Ruike T, Iwabata K, Sugawara F, Sakai H, Abe M, Sakaguchi K - PLoS ONE (2015)

Effect of various treatments on the enhancement effect of cattle saliva.(a) Denatured and dialyzed cattle saliva. Denaturation of cattle saliva: Cattle saliva was autoclaved for 13 minites at 121°C to denature proteins. After that, the saliva was centrifuged at 20,400 x g for 10 min. The supernatant (called ‘Autoclaved saliva’) was collected and subsequently used in experiments. Dialysis of cattle saliva: Cattle saliva was dialyzed against distilled water for 72 h at room temperture. The water was exchanged every other day. (b) Proteinase K treatment. Twenty microliters cattle saliva was mixed with 20 μL proteinase K (20 mg/mL) and the mixture was incubated at 50°C for 12 h. After the incubation, the mixture was incubated at 96°C for 10 min to denature proteinase K. This mixture was called ‘Proteinase K Saliva’ and used in the cellulose degradation assay. The concentration of cattle saliva in the reaction mixture was 5%. All experiments were performed in triplicate and average mean values were plotted. Error bars indicate ± standard deviations. Values labeled with asterisk are statistically different as established by Student's t-test (P < 0.05).
© Copyright Policy
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4581621&req=5

pone.0138902.g003: Effect of various treatments on the enhancement effect of cattle saliva.(a) Denatured and dialyzed cattle saliva. Denaturation of cattle saliva: Cattle saliva was autoclaved for 13 minites at 121°C to denature proteins. After that, the saliva was centrifuged at 20,400 x g for 10 min. The supernatant (called ‘Autoclaved saliva’) was collected and subsequently used in experiments. Dialysis of cattle saliva: Cattle saliva was dialyzed against distilled water for 72 h at room temperture. The water was exchanged every other day. (b) Proteinase K treatment. Twenty microliters cattle saliva was mixed with 20 μL proteinase K (20 mg/mL) and the mixture was incubated at 50°C for 12 h. After the incubation, the mixture was incubated at 96°C for 10 min to denature proteinase K. This mixture was called ‘Proteinase K Saliva’ and used in the cellulose degradation assay. The concentration of cattle saliva in the reaction mixture was 5%. All experiments were performed in triplicate and average mean values were plotted. Error bars indicate ± standard deviations. Values labeled with asterisk are statistically different as established by Student's t-test (P < 0.05).
Mentions: We next attempted to identify the substance in the cattle saliva that was responsible for enhancing the degradation of cellulose. Cattle saliva contained many different types of minerals and organic substances, including sialic acid, mucin, lactoferrin, IGF-1, sodium bicarbonate, phosphoric salt and metal ions. In order to determine whether the substance is a small or a polymer molecule, we first dialyzed the cattle saliva and then used the dialyzed cattle saliva in the cellulose degradation assay. As shown in Fig 3A, we observed no significant difference between the amounts of reducing sugar produced using dialyzed cattle saliva and un-dialyzed cattle saliva. As the pore size of the dialysis membrane is 25–50 Å, only small molecules of sizes less than 14 kDa, such as sialic acid, IGF-1, sodium bicarbonate, phosphoric salt and metal ions, would diffuse across this membrane during dialysis. As a result, these small molecules are expected to be absent in the dialyzed cattle saliva. Thus, these small molecules in cattle saliva were not responsible for enhancing the enzymatic activity of cellulase. Incidentally, most of the polymer molecules known to be present in the cattle saliva are proteins and glycoproteins.

Bottom Line: Although cattle saliva, by itself, did not degrade cellulose, it enhanced the cellulase-catalyzed degradation of cellulose.Thus, the amount of reducing sugar produced increased approximately 2.9-fold by the addition of cattle saliva.We also found that non-enzymatic proteins, which were present in cattle saliva, were responsible for causing the enhancement effect.

View Article: PubMed Central - PubMed

Affiliation: Research Institute for Science and Technology, Tokyo University of Science, Noda, Chiba, Japan.

ABSTRACT
Saccharification of cellulose is a promising technique for producing alternative source of energy. However, the efficiency of conversion of cellulose into soluble sugar using any currently available methodology is too low for industrial application. Many additives, such as surfactants, have been shown to enhance the efficiency of cellulose-to-sugar conversion. In this study, we have examined first whether cattle saliva, as an additive, would enhance the cellulase-catalyzed hydrolysis of cellulose, and subsequently elucidated the mechanism by which cattle saliva enhanced this conversion. Although cattle saliva, by itself, did not degrade cellulose, it enhanced the cellulase-catalyzed degradation of cellulose. Thus, the amount of reducing sugar produced increased approximately 2.9-fold by the addition of cattle saliva. We also found that non-enzymatic proteins, which were present in cattle saliva, were responsible for causing the enhancement effect. Third, the mechanism of cattle saliva mediated enhancement of cellulase activity was probably similar to that of the canonical surfactants. Cattle saliva is available in large amounts easily and cheaply, and it can be used without further purification. Thus, cattle saliva could be a promising additive for efficient saccharification of cellulose on an industrial scale.

No MeSH data available.