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Systematic studies of the interactions between a model polyphenol compound and microbial ?-glucosidases.

ABSTRACT: Lignin is a major obstacle for cost-effective conversion of cellulose into fermentable sugars. Non-productive adsorption onto insoluble lignin fragments and interactions with soluble phenols are important inhibition mechanisms of cellulases, including ?-glucosidases. Here, we examined the inhibitory effect of tannic acid (TAN), a model polyphenolic compound, on ?-glucosidases from the bacterium Thermotoga petrophila (TpBGL1 and TpBGL3) and archaeon Pyrococcus furiosus (PfBGL1). The results revealed that the inhibition effects on ?-glucosidases were TAN concentration-dependent. TpBGL1 and TpBGL3 were more tolerant to the presence of TAN when compared with PfBGL1, while TpBGL1 was less inhibited when compared with TpBGL3. In an attempt to better understand the inhibitory effect, the interaction between TAN and ?-glucosidases were analyzed by isothermal titration calorimetry (ITC). Furthermore, the exposed hydrophobic surface areas in ?-glucosidases were analyzed using a fluorescent probe and compared with the results of inhibition and ITC. The binding constants determined by ITC for the interactions between TAN and ?-glucosidases presented the same order of magnitude. However, the number of binding sites and exposed hydrophobic surface areas varied for the ?-glucosidases studied. The binding between TAN and ?-glucosidases were driven by enthalpic effects and with an unfavorable negative change in entropy upon binding. Furthermore, the data suggest that there is a high correlation between exposed hydrophobic surface areas and the number of binding sites on the inhibition of microbial ?-glucosidases by TAN. These studies can be useful for biotechnological applications.

SUBMITTER: da Silva VM

PROVIDER: S-EPMC5519169 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Systematic studies of the interactions between a model polyphenol compound and microbial β-glucosidases.

da Silva Viviam M VM Sato Juliana A P JAP Araujo Juscemácia N JN Squina Fabio M FM Muniz João R C JRC Riske Karin A KA Garcia Wanius W

PloS one 20170720 7

Lignin is a major obstacle for cost-effective conversion of cellulose into fermentable sugars. Non-productive adsorption onto insoluble lignin fragments and interactions with soluble phenols are important inhibition mechanisms of cellulases, including β-glucosidases. Here, we examined the inhibitory effect of tannic acid (TAN), a model polyphenolic compound, on β-glucosidases from the bacterium Thermotoga petrophila (TpBGL1 and TpBGL3) and archaeon Pyrococcus furiosus (PfBGL1). The results revea ...[more]

PMID: 28727856

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Project description:BackgroundThe production of glucose from cellulose requires cellulases, which are obtained from decomposing microorganisms such as fungi and bacteria. Among the cellulases, β-glucosidases convert cellobiose to glucose and have low concentration in commercial cocktails used for the production of second-generation (2G) ethanol. Genetic engineering can be used to produce recombinant β-glucosidases, and cyanobacteria may be interesting bioreactors. These photosynthetic microorganisms can be cultured using CO2 emitted from the first-generation ethanol (1G) industry as a carbon source. In addition, vinasse, an effluent of 1G ethanol production, can be used as a source of nitrogen for cyanobacteria growth. Thus, photosynthetic bioreactors cannot only produce cellulases at a lower cost, but also reduce the environmental impact caused by residues of 1G ethanol production.ResultsIn the present work, we produced a strain of Synechococcus elongatus capable of expressing high levels of a heterologous β-glucosidase from a microorganism from the Amazonian soil. For this, the pET system was cloned into cyanobacteria genome. This system uses a dedicated T7 RNA polymerase for the expression of the gene of interest under the control of a nickel-inducible promoter. The results showed that the pET system functions efficiently in S. elongatus, once nickel induced T7 RNA polymerase expression which, in turn, induced expression of the gene of the microbial β-glucosidase at high levels when compared with non-induced double transgenic strain. β-glucosidase activity was more than sevenfold higher in the transformed cyanobacteria than in the wild-type strain.ConclusionsThe T7 system promotes high expression levels of the cloned gene in S. elongatus, demonstrating that the arrangement in which an exclusive RNA polymerase is used for transcription of heterologous genes may contribute to high-level gene expression in cyanobacteria. This work was the first to demonstrate the use of cyanobacteria for the production of recombinant β-glucosidases. This strategy could be an alternative to reduce the release of 1G ethanol by-products such as CO2 and vinasse, not only contributing to decrease the cost of β-glucosidase production, but also mitigating the environmental impacts of ethanol industrial plants.

Dataset Information

Systematic studies of the interactions between a model polyphenol compound and microbial ?-glucosidases.

Publications

Systematic studies of the interactions between a model polyphenol compound and microbial β-glucosidases.

Similar Datasets

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