Synergism of cellulases and amylolytic enzymes in the hydrolysis of microalgal carbohydrates

Abstract

This study aimed to evaluate the synergism of cellulases and amylolytic enzymes in the hydrolysis of microalgal carbohydrates for bioethanol production. The effect of β‐glucosidase on the hydrolysis of algal cellulose, and the comparison between the effect of the addition of α‐amylase and amyloglucosidase separately or together on the hydrolysis of algal starch, have not been described previously. Results showed that β‐glucosidases promoted the enzymatic hydrolysis of algal cellulose as a result of the increase in the glucose production rate and the decrease in the inhibition by cellobiose. It was also beneficial to carry out the hydrolysis of algal starch using the mixture of α‐amylase and amyloglucosidase. The results obtained revealed that, in enzymatic hydrolysis experiments, simultaneous treatment with Celluclast 1.5 L, β‐glucosidase, α‐amylase, and amyloglucosidase was a promising strategy to reduce the hydrolysis time required to achieve a higher yield of glucose. Subsequently, fermentation of enzymatic hydrolysates of microalgae using Saccharomyces cerevisiae showed a yield of 0.126 g ethanol / g dried algae. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd

Chemo-Enzymatic Saccharification Strategy of Microalgae Chlorella Sorokiniana

“…For low enzyme concentrations, the combination of two enzymes simultaneously, after the acid treatment, was more efficient than the sequential addition, first a-amylase followed by the addition of amyloglucosidase. These results are in agreement with the reported by Shokrkar et al [10], who describes that the simultaneous addition of these enzymes increased the rate of sugars production, with 20% of reducing sugar content for a 12 h of microalgae enzymatic hydrolysis. Our sugar content is similar and was obtained in less time, only 3 h. The authors Shokrkar et al [10] work only with low enzyme concentrations, and it is not possible to predict the results for higher enzyme concentrations.…”

“…Considering the results obtained from the selected enzyme concentrations, we can verify that the fact that Shokrkar et al [10] used a mixed culture of algae and in our study, we focus in only one microalga, this point has an impact on the obtained results. Shokrkar et al [10] using 50 U/g of aamylase during 12 h obtained 19% and we with our study, in 3 h we obtained 23.48 ± 1.13% (w/w). We proved, at least, in our case with the strain Chlorella sorokiniana that less time can produces similar sugar content.…”

“…To find the best concentration of the a-amylase enzyme, were tested different concentrations, some of which are already described in the literature [10,15,16]. The concentrations tested was 50, 500, 5000 and 8000 U/g (Fig.…”

“…Some papers report only the use of acid hydrolysis, as Ngamsirisomsakul et al [8] suggested the use of sulfuric acid as suitable for biomass hydrolysis. For Kim et al [9], sulfuric acid hydrolysis was more efficient than enzymatic treatment with pectinases, amylases, and cellulases for the microalgae C. vulgaris while, Shokrkar et al [10], reports the use only the enzymatic hydrolysate with the simultaneous use of cellulases, amylases, amyloglucosidase.…”

Model‐based evaluation of continuous bioethanol production plant

“…However, yeasts, and in particular strains of Saccharomyces cerevisiae , are the primary microorganisms for bioethanol production and are capable of fermenting the main sugar feedstock such as glucose, fructose, and sucrose under large‐scale industrial production conditions . Ethanol tolerance and high ethanol yield make S. cerevisiae a promising and economically feasible strain for large‐scale bioethanol production …”