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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.


Related in: MedlinePlus

Effects of cattle saliva on cellulose degradation.(a) Enhancement effect of cattle saliva. Effect of cattle saliva addition on the production of reducing sugar from micro-crystalline cellulose. Reaction mixtures containing 10 μg/mL cellulase and 0.8% (wt%) cellulose were incubated in the presence or absence of 10% cattle saliva at 50°C for 24 h. Effects of (b) cellulase concentration, (c) incubation time and (d) cattle saliva concentration on reducing sugar production. In (b), concentrations of cellulase used were 0, 1, 5, 10, 50, 100, 500 and 1000 μg/mL, while the concentration of cellulose was kept same as in (a) above and the reaction mixtures were incubated at 50°C for 24 h. In (c), different incubation times were used (0, 1, 3, 6, 12, 24, 48 and 72 h) while keeping the composition of the reaction mixture same as in (a) above. In (d), different concentrations of cattle saliva were used here: 0, 0.5, 1, 2, 3, 4, 7 and 10%; concentrations of cellulase and cellulose and reaction conditions were same as in (a) above. All experiments were performed in triplicate and results are expressed as average means. 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.g001: Effects of cattle saliva on cellulose degradation.(a) Enhancement effect of cattle saliva. Effect of cattle saliva addition on the production of reducing sugar from micro-crystalline cellulose. Reaction mixtures containing 10 μg/mL cellulase and 0.8% (wt%) cellulose were incubated in the presence or absence of 10% cattle saliva at 50°C for 24 h. Effects of (b) cellulase concentration, (c) incubation time and (d) cattle saliva concentration on reducing sugar production. In (b), concentrations of cellulase used were 0, 1, 5, 10, 50, 100, 500 and 1000 μg/mL, while the concentration of cellulose was kept same as in (a) above and the reaction mixtures were incubated at 50°C for 24 h. In (c), different incubation times were used (0, 1, 3, 6, 12, 24, 48 and 72 h) while keeping the composition of the reaction mixture same as in (a) above. In (d), different concentrations of cattle saliva were used here: 0, 0.5, 1, 2, 3, 4, 7 and 10%; concentrations of cellulase and cellulose and reaction conditions were same as in (a) above. All experiments were performed in triplicate and results are expressed as average means. Error bars indicate ± standard deviations. Values labeled with asterisk are statistically different as established by Student's t-test (P < 0.05).

Mentions: First, we examined the effect of cattle saliva on cellulose hydrolysis. Fig 1A shows the results of adding cattle saliva to a mixture containing microcrystalline cellulose and cellulase (Cellulose + Cellulase + Saliva). We also confirmed the effect of the combinations of ‘Cellulose + Cellulase’, ‘Cellulase + Saliva’ and ‘Cellulase + Saliva’ on cellulose degradation, as controls. The concentrations of reducing sugar (and the conversion rates to reducing sugar) found in the ‘Cellulose + Cellulase + Saliva’ mixture, ‘Cellulose + Cellulase’ mixture, ‘Cellulose + Saliva’ mixture and ‘Cellulase + Saliva’ mixture were 0.259 mg/mL (3.24%), 0.088 mg/mL (1.10%), not detected and not detected, respectively. Thus, the amount of reducing sugar produced from cellulose increased approximately 2.9-fold by the addition of cattle saliva. Together, these results suggested that cattle saliva does not degrade cellulose by itself, but enhances cellulase-catalyzed hydrolysis of cellulose. We obtained virtually same results using saliva from other cattle (data not shown), thus suggesting that the observed enhancing effect of cattle saliva was not individual specific.


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)

Effects of cattle saliva on cellulose degradation.(a) Enhancement effect of cattle saliva. Effect of cattle saliva addition on the production of reducing sugar from micro-crystalline cellulose. Reaction mixtures containing 10 μg/mL cellulase and 0.8% (wt%) cellulose were incubated in the presence or absence of 10% cattle saliva at 50°C for 24 h. Effects of (b) cellulase concentration, (c) incubation time and (d) cattle saliva concentration on reducing sugar production. In (b), concentrations of cellulase used were 0, 1, 5, 10, 50, 100, 500 and 1000 μg/mL, while the concentration of cellulose was kept same as in (a) above and the reaction mixtures were incubated at 50°C for 24 h. In (c), different incubation times were used (0, 1, 3, 6, 12, 24, 48 and 72 h) while keeping the composition of the reaction mixture same as in (a) above. In (d), different concentrations of cattle saliva were used here: 0, 0.5, 1, 2, 3, 4, 7 and 10%; concentrations of cellulase and cellulose and reaction conditions were same as in (a) above. All experiments were performed in triplicate and results are expressed as average means. 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

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getmorefigures.php?uid=PMC4581621&req=5

pone.0138902.g001: Effects of cattle saliva on cellulose degradation.(a) Enhancement effect of cattle saliva. Effect of cattle saliva addition on the production of reducing sugar from micro-crystalline cellulose. Reaction mixtures containing 10 μg/mL cellulase and 0.8% (wt%) cellulose were incubated in the presence or absence of 10% cattle saliva at 50°C for 24 h. Effects of (b) cellulase concentration, (c) incubation time and (d) cattle saliva concentration on reducing sugar production. In (b), concentrations of cellulase used were 0, 1, 5, 10, 50, 100, 500 and 1000 μg/mL, while the concentration of cellulose was kept same as in (a) above and the reaction mixtures were incubated at 50°C for 24 h. In (c), different incubation times were used (0, 1, 3, 6, 12, 24, 48 and 72 h) while keeping the composition of the reaction mixture same as in (a) above. In (d), different concentrations of cattle saliva were used here: 0, 0.5, 1, 2, 3, 4, 7 and 10%; concentrations of cellulase and cellulose and reaction conditions were same as in (a) above. All experiments were performed in triplicate and results are expressed as average means. Error bars indicate ± standard deviations. Values labeled with asterisk are statistically different as established by Student's t-test (P < 0.05).
Mentions: First, we examined the effect of cattle saliva on cellulose hydrolysis. Fig 1A shows the results of adding cattle saliva to a mixture containing microcrystalline cellulose and cellulase (Cellulose + Cellulase + Saliva). We also confirmed the effect of the combinations of ‘Cellulose + Cellulase’, ‘Cellulase + Saliva’ and ‘Cellulase + Saliva’ on cellulose degradation, as controls. The concentrations of reducing sugar (and the conversion rates to reducing sugar) found in the ‘Cellulose + Cellulase + Saliva’ mixture, ‘Cellulose + Cellulase’ mixture, ‘Cellulose + Saliva’ mixture and ‘Cellulase + Saliva’ mixture were 0.259 mg/mL (3.24%), 0.088 mg/mL (1.10%), not detected and not detected, respectively. Thus, the amount of reducing sugar produced from cellulose increased approximately 2.9-fold by the addition of cattle saliva. Together, these results suggested that cattle saliva does not degrade cellulose by itself, but enhances cellulase-catalyzed hydrolysis of cellulose. We obtained virtually same results using saliva from other cattle (data not shown), thus suggesting that the observed enhancing effect of cattle saliva was not individual specific.

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.


Related in: MedlinePlus