Biosynthesis, purification and characterization of endoglucanase from a xylanase producing strain Aspergillus niger B03

Dobrev, Georgi; Zhekova, Boriana

doi:10.1590/s1517-83822012000100008

Cited by 10 publications

(4 citation statements)

References 20 publications

(19 reference statements)

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“…BcsZ could hydrolyze CMC-Na, RAC and glucan. BcsZ had a higher affinity for CMC than Thcel9A (12.02 mg/mL) from Thermobifida halotolerans YIM 90462 T [25], the purified endoglucanase (21.01 mg/mL) from Aspergillus niger B03 [26] and C67–1 (37 mg/mL) from metagenomes of buffalo rumens [27]. It had a weaker affinity for CMC than the endoglucanase from Bacillus sp.…”

Section: Discussionmentioning

confidence: 99%

Identification and characterization of an Endo-glucanase secreted from cellulolytic Escherichia coli ZH-4

et al. 2019

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Background In the previous study, the cellulolytic Escherichia coli ZH-4 isolated from bovine rumen was found to show extracellular cellulase activity and could degrade cellulose in the culture. The goal of this work was to identify and characterize the secreted cellulase of E. coli ZH-4. It will be helpful to re-understand E. coli and extend its application in industry. Results A secreted cellulase was confirmed to be endo-glucanase BcsZ which was encoded by bcsZ gene and located in the cellulose synthase operon bcsABZC in cellulolytic E. coli ZH-4 by western blotting. Characterization of BcsZ indicated that a broad range of pH and temperature tolerance with optima at pH 6.0 and 50 °C, respectively. The apparent Michaelis–Menten constant (K m ) and maximal reaction rate (V max ) for BcsZ were 8.86 mg/mL and 0.3 μM/min·mg, respectively. Enzyme activity of BcsZ was enhanced by Mg 2+ and inhibited by Zn 2+ , Cu 2+ and Fe 3+ . BcsZ could hydrolyze carboxymethylcellulose (CMC) to produce cello-oligosaccharides, cellotriose, cellobiose and glucose. Conclusions It is confirmed that extracellular cellulolytic capability of E. coli ZH-4 was attributed to BcsZ, which explained why E. coli ZH-4 can grow on cellulose. The endo-glucanase BcsZ from E. coli -ZH4 has some new characteristics which will extend the understanding of endo-glucanase. Analysis of the secretion characteristics of BcsZ provided a great reference for applying E. coli in multiple industrial fields.

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Section: Discussionmentioning

confidence: 99%

Identification and characterization of an Endo-glucanase secreted from cellulolytic Escherichia coli ZH-4

et al. 2019

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“…The hydrolysis of Avicel using an enzyme mixture of commercial cellulase and β-glucosidase (Novozymes) provided a lower carbohydrate conversion of 69.6% at 96 h (Yu et al, 2012), as compared to that of our enzyme mixture (75% conversion at 100 h). For the hydrolysis of milled corncob using the purified enzyme mixture of endoglucanase and endoxylanase from Aspergillus niger B03, it gave a reducing sugar of 540 mg/L (Dobrev and Zhekova, 2012), which is lower than that in the present work (987 mg/L). These results reveal that crude EglS has great potential to be utilized for the enhancement of commercial cellulase, especially for the enzymatic hydrolysis of agricultural residues.…”

Section: Enzymatic Hydrolysis Of Various Cellulosic Substratescontrasting

confidence: 82%

“…coli BL 21(DE) expressing endoglucanase gene from Thermobifida halotolerans YIM 90462 (Km of 37 mg/mL) and purified endoglucanase from Aspergillus niger B03 (Km of 21.01 mg/mL) (Dobrev and Zhekova, 2012), but lower than the purified cellulase from Bacillus sp. MSL2 (Km of 0.8 mg/mL) (Sriariyanun et al, 2016).…”

Section: Egls Enzyme Characterization Resultsmentioning

confidence: 99%

Microbial conversion of cellulose to sugars by bacterial enzyme

Seneesrisakul

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This work studied the conversion of lignocellulosic materials to sugars, the intermediates for bioethanol production, by a bacterial enzyme. Due to the complex structure of lignocellulose, a cellulase enzyme cannot effectively access and hydrolyse cellulose fibers. Various pretreatment processes of lignocellulose have been studied to enhance enzymatic hydrolysis to date. In this work, corncob was firstly studied for microbial pretreatment using three microorganisms including two bacterial strains of Bacillus subtilis A 002 and Cellulomonas sp. TISTR 784 and a fungal strain of Phanerochaete sordida SK7. The results showed that the microbial pretreatment with P. sordida SK7 was the most effective for enhancing enzymatic hydrolysis with approximately 40% improvement, compared to no treatment. Whereas, Bacillus subtilis A 002 was able to hydrolyse some cellulose fraction in lignocellulose but the reducing sugar concentration was very low due to its simultaneously consumption. In the following part, the native cellulase-producing bacteria B. subtilis was developed to produce enzyme at high level using PCR-based cloning technique. Endoglucanse gene encoding from B. subtilis M015 was cloned into plasmid (pFLAG-CTS) and transferred into E. coli JE5505. The clone, named E. coli Glu5, could greatly produce endoglucanase with higher enzymatic activity than that of the native strain, approximately 17 times. Finally, E. coli Glu5 was used for a microbial hydrolysis of soluble cellulose (carboxymethyl cellulose) in a continuous bubble reactor. The results demonstrate the feasibility to consolidate the steps of enzyme production and enzymatic hydrolysis together in continuous system at a low organic loading rate of 5 kg/m3d.

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“…This result was attributed to the higher level of hydrolysis of CMC compared with the other substrates. Endoglucanase has high substrate specificity for CMC and lower specificity for crystalline forms of cellulose (Kim 1995;Dobrev and Zhekova 2012;Miotto et al 2014). Hence, endoglucanase, produced by the medium, must have hydrolysed the CMC better, thus producing higher amounts of reducing sugar than the other substrates.…”

Section: Reducing Sugar Productionmentioning

confidence: 99%

Enhanced Endoglucanase Production by Bacillus aerius on Mixed Lignocellulosic Substrates

2016

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Selected carbon sources including soluble carboxymethyl cellulose (CMC), insoluble microcrystalline cellulose (MCC), and single (SS)/mixed lignocellulosic substrates (MS), were evaluated for endoglucanase production by B. aerius S5.2. The lignocellulosic substrates of oil palm empty fruit bunch (EFB), oil palm frond (OPF), rice husk (RH), and their mixture (MS) supported growth of the strain better than CMC and MCC. The maximum endoglucanase activity on MS was 7.3-, 2.6-, 1.7-, and 1.2-fold higher than those recorded on MCC, CMC, EFB/OPF, and RH, respectively. While the reducing sugar concentration of the CMC medium was comparable to that of the EFB and MS media, wide variability was observed in the reducing sugar concentrations among the lignocellulosic substrates. Extremely low levels of sugar were detected in the MCC medium, reflecting its poor digestibility and hence unsuitability for growth and endoglucanase production. Endoglucanase production was predominantly extracellular when the strain was grown on CMC and MS. After seven days of fermentation, there was an approximately 25% reduction in MS dry weight. These findings show that the use of mixed lignocellulosics could potentially reduce the cost of cellulase production. Certain novel aspects of the cellulase system of B. aerius are reported in this study.

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Biosynthesis, purification and characterization of endoglucanase from a xylanase producing strain Aspergillus niger B03

Cited by 10 publications

References 20 publications

Identification and characterization of an Endo-glucanase secreted from cellulolytic Escherichia coli ZH-4

Identification and characterization of an Endo-glucanase secreted from cellulolytic Escherichia coli ZH-4

Microbial conversion of cellulose to sugars by bacterial enzyme

Enhanced Endoglucanase Production by Bacillus aerius on Mixed Lignocellulosic Substrates

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