Improved lignocellulose conversion to biofuels with thermophilic bacteria and thermostable enzymes

Bhalla, Aditya; Bansal, Namita; Kumar, Sudhir; Bischoff, Kenneth M.; Sani, Rajesh K.

doi:10.1016/j.biortech.2012.10.145

Cited by 293 publications

(190 citation statements)

References 119 publications

Supporting

Mentioning

183

Contrasting

Unclassified

Order By: Relevance

“…The significant increases in AaCel9A thermostability accompanied by the enhanced specific activity of mutants D468A and D468V favor high-temperature cellulose hydrolysis to achieve a higher conversion rate and reduce the enzyme cost of cellulosic alcohol production (1,15). The thermostable enzymes that catalyzed optimally under acid conditions (Fig.…”

Section: Figmentioning

confidence: 99%

“…ellulose is the most abundant natural polysaccharide and is utilized to generate bioalcohol as a sustainable alternative to fossil fuels (1). Owing to its complex structure, the efficient degradation of cellulose is essential for the production of bioalcohol.…”

mentioning

confidence: 99%

“…Endoglucanases cleave internal ␤-1,4 glycosidic linkages of the polymeric cellulose and act synergistically with exoglucanases and ␤-glucosidases during cellulose hydrolysis (2,3). The use of thermostable cellulases can reduce industrial cost by increasing the enzymatic hydrolysis rates at high temperature, thereby decreasing the enzyme dosage requirements (1). Performing cellulose hydrolysis at high temperature also can decrease microbial contamination problems.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Polarity Alteration of a Calcium Site Induces a Hydrophobic Interaction Network and Enhances Cel9A Endoglucanase Thermostability

Wang

Hsiao

Chen

et al. 2016

Appl Environ Microbiol

View full text Add to dashboard Cite

Structural calcium sites control protein thermostability and activity by stabilizing native folds and changing local conformations. Alicyclobacillus acidocaldarius survives in thermal-acidic conditions and produces an endoglucanase Cel9A (AaCel9A) which contains a calcium-binding site (Ser465 to Val470) near the catalytic cleft. By superimposing the Ca 2؉ -free and Ca 2؉ -bounded conformations of the calcium site, we found that Ca 2؉ induces hydrophobic interactions between the calcium site and its nearby region by driving a conformational change. The hydrophobic interactions at the high-B-factor region could be enhanced further by replacing the surrounding polar residues with hydrophobic residues to affect enzyme thermostability and activity. Therefore, the calcium-binding residue Asp468 (whose side chain directly ligates Ca 2؉ ), Asp469, and Asp471 of AaCel9A were separately replaced by alanine and valine. Mutants D468A and D468V showed increased activity compared with those of the wild type with 0 mM or 10 mM Ca 2؉ added, whereas the Asp469 or Asp471 substitution resulted in decreased activity. The D468A crystal structure revealed that mutation D468A triggered a conformational change similar to that induced by Ca 2؉ in the wild type and developed a hydrophobic interaction network between the calcium site and the neighboring hydrophobic region (Ala113 to Ala117). Mutations D468V and D468A increased 4.5°C and 5.9°C, respectively, in melting temperature, and enzyme half-life at 75°C increased approximately 13 times. Structural comparisons between AaCel9A and other endoglucanases of the GH9 family suggested that the stability of the regions corresponding to the AaCel9A calcium site plays an important role in GH9 endoglucanase catalysis at high temperature.

show abstract

Section: Figmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Polarity Alteration of a Calcium Site Induces a Hydrophobic Interaction Network and Enhances Cel9A Endoglucanase Thermostability

Wang

Hsiao

Chen

et al. 2016

Appl Environ Microbiol

View full text Add to dashboard Cite

show abstract

“…The main disadvantage of SSF is that the optimum temperature for cellulases activity (45-60 °C) is commonly higher that the temperatures suitable for the activity of yeast and many bacterial biofuel fermentations (Brethauer and Wyman, 2010;Bhalla et al, 2013;Kumagai et al, 2014).…”

Section: Simultaneous Saccharification and Fermentation (Ssf)mentioning

confidence: 99%

Advances in consolidated bioprocessing systems for bioethanol and butanol production from biomass: a comprehensive review

2015

View full text Add to dashboard Cite

HIGHLIGHTS Various CBP strategies have been discussed. Recently, lignocellulosic biomass as the most abundant renewable resource has been widely considered for bioalcohols production. However, the complex structure of lignocelluloses requires a multi-step process which is costly and time consuming. Although, several bioprocessing approaches have been developed for pretreatment, saccharification and fermentation, bioalcohols production from lignocelluloses is still limited because of the economic infeasibility of these technologies. This cost constraint could be overcome by designing and constructing robust cellulolytic and bioalcohols producing microbes and by using them in a consolidated bioprocessing (CBP) system. This paper comprehensively reviews potentials, recent advances and challenges faced in CBP systems for efficient bioalcohols (ethanol and butanol) production from lignocellulosic and starchy biomass. The CBP strategies include using native single strains with cellulytic and alcohol production activities, microbial co-cultures containing both cellulytic and ethanologenic microorganisms, and genetic engineering of cellulytic microorganisms to be alcohol-producing or alcohol producing microorganisms to be cellulytic. Moreover, high-throughput techniques, such as metagenomics, metatranscriptomics, next generation sequencing and synthetic biology developed to explore novel microorganisms and powerful enzymes with high activity, thermostability and pH stability are also discussed. Currently, the CBP technology is in its infant stage, and ideal microorganisms and/or conditions at industrial scale are yet to be introduced. So, it is essential to bring into attention all barriers faced and take advantage of all the experiences gained to achieve a high-yield and low-cost CBP process.

show abstract

“…6,7 Actinobacteria are a phylum of Gram-positive bacteria that are found abundantly in soil. 8 They include some of the most prolific lignocellulose-degrading bacteria.…”

Section: Introductionmentioning

confidence: 99%

Bioinformatic Analysis of Glycoside Hydrolases in the Proteomes of Mesophilic and Thermophilic Actinobacteria

Barabote¹

2017

MOJPB

View full text Add to dashboard Cite

Petroleum reserves are rapidly depleting and alternative renewable sources of energy need to be developed to meet the energy demands of the planet. Lignocellulose has been recognized as a highly promising and renewable resource for the development of clean energy. Thermophilic microbes and thermostable enzymes are being sought for biological conversion of lignocellulose into biofuels. The phylum Actinobacteria includes several efficient cellulose-degrading microorganisms. Genomes of several Actinobacteria have been completely sequenced and deposited in public databases, which are a great resource for uncovering new enzymes and targets for biotechnology. We searched the predicted proteomes of 69 Actinobacteria for the homologs of 20 glycoside hydrolase families relevant to lignocellulose degradation and identified 589 glycoside hydrolase homologs. We analyzed (1) the distribution of the glycoside hydrolase homologs across mesophilic and thermophilic Actinobacteria (2), the domain architecture of cellulases (from GH5 and GH6 families) and xylanases (from GH10 and GH11 families) from mesophilic and thermophilic Actinobacteria, and (3) asymmetric amino acid substitutions between mesophilic and thermophilic glycoside hydrolases. Overall, our data provide new insights into the distribution of different glycoside hydrolases in Actinobacteria as well as into the thermostability features of cellulases and xylanases from Actinobacteria. Our findings provide a basis for genetic engineering of glycoside hydrolases as well as new targets for biotechnology. Keywords

show abstract

Improved lignocellulose conversion to biofuels with thermophilic bacteria and thermostable enzymes

Cited by 293 publications

References 119 publications

Polarity Alteration of a Calcium Site Induces a Hydrophobic Interaction Network and Enhances Cel9A Endoglucanase Thermostability

Polarity Alteration of a Calcium Site Induces a Hydrophobic Interaction Network and Enhances Cel9A Endoglucanase Thermostability

Advances in consolidated bioprocessing systems for bioethanol and butanol production from biomass: a comprehensive review

Bioinformatic Analysis of Glycoside Hydrolases in the Proteomes of Mesophilic and Thermophilic Actinobacteria

Contact Info

Product

Resources

About