Construction of <i>Hansenula polymorpha</i> strains with improved thermotolerance

Ishchuk, Olena P.; Voronovsky, Andriy Y.; Abbas, Charles A.; Sibirny, Andriy А.

doi:10.1002/bit.22457

Cited by 50 publications

(25 citation statements)

References 51 publications

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“…The most common approach to altering the thermal growth parameters of microbes is genetic engineering, and a panoply of molecular biological tools have been brought to bear on the problem (1,8,16,22,34,38,55,62). The most success has been achieved using advanced high-throughput recombinant engineering techniques, because they either sample many random genetic variations (some of which may have originated in thermophiles) or affect highly pleiotropic genes and thus can access the genetic or biochemical diversity required to significantly alter complex traits, such as optimal growth temperature (T opt ) or maximal growth temperature (T max ).…”

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confidence: 99%

Experimental Evolution of a Facultative Thermophile from a Mesophilic Ancestor

Blaby¹,

Lyons²,

Wroclawska-Hughes³

et al. 2012

Appl Environ Microbiol

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Experimental evolution via continuous culture is a powerful approach to the alteration of complex phenotypes, such as optimal/ maximal growth temperatures. The benefit of this approach is that phenotypic selection is tied to growth rate, allowing the production of optimized strains. Herein, we demonstrate the use of a recently described long-term culture apparatus called the Evolugator for the generation of a thermophilic descendant from a mesophilic ancestor (Escherichia coli MG1655). In addition, we used whole-genome sequencing of sequentially isolated strains throughout the thermal adaptation process to characterize the evolutionary history of the resultant genotype, identifying 31 genetic alterations that may contribute to thermotolerance, although some of these mutations may be adaptive for off-target environmental parameters, such as rich medium. We undertook preliminary phenotypic analysis of mutations identified in the glpF and fabA genes. Deletion of glpF in a mesophilic wild-type background conferred significantly improved growth rates in the 43-to-48°C temperature range and altered optimal growth temperature from 37°C to 43°C. In addition, transforming our evolved thermotolerant strain (EVG1064) with a wild-type allele of glpF reduced fitness at high temperatures. On the other hand, the mutation in fabA predictably increased the degree of saturation in membrane lipids, which is a known adaptation to elevated temperature. However, transforming EVG1064 with a wildtype fabA allele had only modest effects on fitness at intermediate temperatures. The Evolugator is fully automated and demonstrates the potential to accelerate the selection for complex traits by experimental evolution and significantly decrease development time for new industrial strains.

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mentioning

confidence: 99%

Experimental Evolution of a Facultative Thermophile from a Mesophilic Ancestor

Blaby¹,

Lyons²,

Wroclawska-Hughes³

et al. 2012

Appl Environ Microbiol

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“…Genetic manipulation of this yeast has resulted in an increase in intracellular trehalose and knock out of acid trehalase gene ATH1. In addition, the overexpression of the heat shock proteins Hsp16 and Hsp104 allowed normal xylose fermentation at 50°C (Ishchuk et al, 2009). Ishchuk et al (2010) in a different investigation confirmed that the ethanol tolerance of H. polymorpha could be increased by the overexpression of the heterologous gene MPR1.…”

Section: Hansenula Polymorphamentioning

confidence: 82%

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

2015

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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.

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“…However, it is still a challenge for these ethanologenic microorganisms to directly utilize lignocellulosic biomass at industrial scale. Another strategy for improving fermentation performance of microorganisms is to enhance their tolerance to environmental stress, including thermo-tolerance and inhibitors (e.g., ethanol, acids, furans, phenolics) tolerance [34, [154][155][156]. Various effective strategies, such as random mutagenesis [157], genome shuffling [158][159][160][161], artificial transcription factor engineering [162], global transcription machinery engineering [163][164][165], error-prone whole genome amplification (ep-WGA) [166], have also been developed for this purpose.…”

Section: Strain Improvementmentioning

confidence: 99%

Bioconversion of Lignocellulose into Bioethanol: Process Intensification and Mechanism Research

Huang

et al. 2011

Bioenerg. Res.

123

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Biofuels produced from lignocellulosic biomass can significantly reduce the energy dependency on fossil fuels and the resulting effects on environment. In this respect, cellulosic ethanol as an alternative fuel has the potential to become a viable energy source in the near future. Over the past few decades, tremendous effort has been undertaken to make cellulosic ethanol cost competitive with conventional fossil fuels. The pretreatment step is always necessary to deconstruct the recalcitrant structures and to make cellulose more accessible to enzymes. A large number of pretreatment technologies involving physical, chemical, biological, and combined approaches have been developed and tested at the pilot scale. Furthermore, various strategies and methods, including multi-enzyme complex, non-catalytic additives, enzyme recycling, high solids operation, design of novel bioreactors, and strain improvement have also been implemented to improve the efficiency of subsequent enzymatic hydrolysis and fermentation. These technologies provide significant opportunities for lower total cost, thus making large-scale production of cellulosic ethanol possible. Meanwhile, many researchers have focused on the key factors that limit cellulose hydrolysis, and analyzing the reaction mechanisms of cellulase. This review describes the most recent advances on process intensification and mechanism research of pretreatment, enzymatic hydrolysis, and fermentation during the production of cellulosic ethanol.

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Construction of Hansenula polymorpha strains with improved thermotolerance

Cited by 50 publications

References 51 publications

Experimental Evolution of a Facultative Thermophile from a Mesophilic Ancestor

Experimental Evolution of a Facultative Thermophile from a Mesophilic Ancestor

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

Bioconversion of Lignocellulose into Bioethanol: Process Intensification and Mechanism Research

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