Butanol Tolerance in a Selection of Microorganisms

National Renewable Energy Laboratory, National Bioenergy Center, Golden, CO 80401, USA.
Applied biochemistry and biotechnology (Impact Factor: 1.74). 05/2009; 153(1-3):13-20. DOI: 10.1007/s12010-008-8460-4
Source: PubMed


Butanol tolerance is a critical factor affecting the ability of microorganisms to generate economically viable quantities of butanol. Current Clostridium strains are unable to tolerate greater than 2% 1-butanol thus membrane or gas stripping technologies to actively remove butanol during fermentation are advantageous. To evaluate the potential of alternative hosts for butanol production, we screened 24 different microorganisms for their tolerance to butanol. We found that in general, a barrier to growth exists between 1% and 2% butanol and few microorganisms can tolerate 2% butanol. Strains of Escherichia coli, Zymomonas mobilis, and non-Saccharomyces yeasts were unable to surmount the 2% butanol growth barrier. Several strains of Saccharomyces cerevisiae exhibit limited growth in 2% butanol, while two strains of Lactobacillus were able to tolerate and grow in up to 3% butanol.

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Available from: Eric P. Knoshaug, Jun 16, 2015
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    • "After incubation, the isolated colonies were inoculated into agar plate containing 1 to 5 % (v/v) butanol concentration. Several rounds of screening were performed to purify and to isolate strains with high butanol tolerance [1]. "
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    ABSTRACT: Due to a limited supply of petroleum oils, microbial production of butanol has gained more attention in recent years. However, major road blocks of the current butanol fermentation were low yield, low productivity and most importantly low titer due to the toxicity of butanol to their producing strains. In our current research efforts were made to evaluate the potential butanol tolerance bacterial strains for its possible role as a host for butanol production. Among the thirty screened bacterial strains, only few showed tolerance towards butanol in which AS2 I has the capability to tolerate upto 5 % butanol at 72 h with 30 % of cell growth. Assays for different enzymes involved in butanol production were also carried out. from the present study showed that the best butanol tolerant bacteria was found to be Paneibacillus sp. using 16S rDNA sequencing and had enhanced activity of butanol tolerance enzymes. Overall results shows that the strain AS2 I can be engineered as promising host for enhanced butanol production.
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    • "Butanol tolerance was checked in MSA plates containing 1 to 5 % (v/v) butanol with the above said conditions. Several rounds of screening were performed to purify and isolate strains with high butanol tolerance (Sardssai and Bhosle, 2002; Knoshaug et al., 2009). The isolated strain was stored at -20 °C for further use. "
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    ABSTRACT: Butanol tolerance is a complex mechanism affecting the ability of microorganisms to generate economically viable quantities of butanol. The objective of this study was to isolate and characterize butanol tolerant bacterial strains which can act as potential alternative hosts for butanol production. The potential bacterial isolates were screened, based on the non toxic effect on cell growth rate and degradation ability of sago waste which was used as a sole carbon source with butanol enrichment. During this study, it was found that a growth barrier existed between 1 to 5 % butanol concentrations and only few selected isolates could tolerate upto 5% butanol after long term adaptation. Screening of five isolates proved to be more tolerant, which were identified as Bacillus megaterium, B. aryabhattai, B. tequilensis, and B. circulans using 16S rDNA sequence. These isolates were markedly attractive to identify butanol tolerance specific stress response genes and furtherengineered to actas a genetic hostfor biobutanol production.
    Journal of Environmental Biology 11/2014; 35(6). · 0.56 Impact Factor
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    • "If green chemistries are to find wide applications in the production of chemicals and biofuels, metabolic engineering (ME) strategies must be developed in host strains that have the ability to produce the desirable chemicals at high concentrations. The genus Lactobacillus includes some of the most alcoholtolerant organisms known (Couto et al. 1997; G-Alegria et al. 2004; Gold et al. 1992; Knoshaug and Zhang 2009) despite the perception that yeasts are overall more tolerant to ethanol. For example, the sequenced Lactobacillus plantarum (Kleerebezem et al. 2003) has been shown to grow in the presence of up to 13 % (v/v) ethanol (G-Alegria et al. 2004). "
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    ABSTRACT: A major challenge in producing chemicals and biofuels is to increase the tolerance of the host organism to toxic products or byproducts. An Escherichia coli strain with superior ethanol and more generally alcohol tolerance was identified by screening a library constructed by randomly integrating Lactobacillus plantarum genomic DNA fragments into the E. coli chromosome via Cre-lox recombination. Sequencing identified the inserted DNA fragment as the murA2 gene and its upstream intergenic 973-bp sequence, both coded on the negative genomic DNA strand. Overexpression of this murA2 gene and its upstream 973-bp sequence significantly enhanced ethanol tolerance in both E. coli EC100 and wild type E. coli MG1655 strains by 4.1-fold and 2.0-fold compared to control strains, respectively. Tolerance to n-butanol and i-butanol in E. coli MG1655 was increased by 1.85-fold and 1.91-fold, respectively. We show that the intergenic 973-bp sequence contains a native promoter for the murA2 gene along with a long 5' UTR (286 nt) on the negative strand, while a noncoding, small RNA, named MurA2S, is expressed off the positive strand. MurA2S is expressed in E. coli and may interact with murA2, but it does not affect murA2's ability to enhance alcohol tolerance in E. coli. Overexpression of murA2 with its upstream region in the ethanologenic E. coli KO11 strain significantly improved ethanol production in cultures that simulate the industrial Melle-Boinot fermentation process.
    Applied Microbiology and Biotechnology 08/2014; 98(19). DOI:10.1007/s00253-014-6004-0 · 3.34 Impact Factor
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