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Isolation and characterization of new poly(3HB)-accumulating star-shaped cell-aggregates-forming thermophilic bacteria

(2010) JOURNAL OF APPLIED MICROBIOLOGY. 109(5). p.1579-1590
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Abstract
Aims: This study aimed at isolating thermophilic bacteria that utilize cheap carbon substrates for the economically feasible production of poly(3-hydroxybutyrate), poly(3HB), at elevated temperatures. Methods and Results: Thermophilic bacteria were enriched from an aerobic organic waste treatment plant in Germany, and from hot springs in Egypt. Using the viable colony staining method for hydrophobic cellular inclusions with Nile red in mineral salts medium (MSM) containing different carbon sources, six Gram-negative bacteria were isolated. Under the cultivation conditions used in this study, strains MW9, MW11, MW12, MW13 and MW14 formed stable star-shaped cell-aggregates (SSCAs) during growth; only strain MW10 consisted of free-living rod-shaped cells. The phylogenetic relationships of the strains as derived from 16S rRNA gene sequence comparisons revealed them as members of the Alphaproteobacteria. The 16S rRNA gene sequences of the isolates were very similar (> 99% similarity) and exhibited similarities ranging from 93 to 99% with the most closely related species that were Chelatococcus daeguensis, Chelatococcus sambhunathii,Chelatococcus asaccharovorans, Bosea minatitlanensis, Bosea thiooxidans and Methylobacterium lusitanum. Strains MW9, MW10, MW13 and MW14 grew optimally in MSM with glucose, whereas strains MW11 and MW12 preferred glycerol as sole carbon source for growth and poly(3HB) accumulation. The highest cell density and highest poly(3HB) content attained were 4 center dot 8 g l-l (cell dry weight) and 73% (w/w), respectively. Cells of all strains grew at temperatures between 37 and 55 degrees C with the optimum growth at 50 degrees C. Conclusions: New PHA-accumulating thermophilic bacterial strains were isolated and characterized to produce poly(3HB) from glucose or glycerol in MSM at 50 degrees C. SSCAs formation was reported during growth. Significance and Impact of the Study: To the best of our knowledge, this is the first report on the formation of SSCAs by PHA-accumulating bacteria and also by thermophilic bacteria. PHA-producing thermophiles can significantly reduce the costs of fermentative PHA production.
Keywords
BACILLUS SP INT005, thermophiles, SP-NOV., POLY(3-HYDROXYBUTYRATE) PRODUCTION, POLYHYDROXYALKANOIC ACIDS, BIOCHEMICAL-PROPERTIES, MICROBIAL-DEGRADATION, THERMUS-THERMOPHILUS, WASTE-WATER, GEN.-NOV., NILE RED, star-shaped cell-aggregates, poly(3HB) accumulation, Chelatococcus sp, 16S rDNA

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Citation

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Chicago
Ibrahim, Mohammad, Anne Willems, and Alexander Steinbüchel. 2010. “Isolation and Characterization of New poly(3HB)-accumulating Star-shaped Cell-aggregates-forming Thermophilic Bacteria.” Journal of Applied Microbiology 109 (5): 1579–1590.
APA
Ibrahim, M., Willems, A., & Steinbüchel, A. (2010). Isolation and characterization of new poly(3HB)-accumulating star-shaped cell-aggregates-forming thermophilic bacteria. JOURNAL OF APPLIED MICROBIOLOGY, 109(5), 1579–1590.
Vancouver
1.
Ibrahim M, Willems A, Steinbüchel A. Isolation and characterization of new poly(3HB)-accumulating star-shaped cell-aggregates-forming thermophilic bacteria. JOURNAL OF APPLIED MICROBIOLOGY. 2010;109(5):1579–90.
MLA
Ibrahim, Mohammad, Anne Willems, and Alexander Steinbüchel. “Isolation and Characterization of New poly(3HB)-accumulating Star-shaped Cell-aggregates-forming Thermophilic Bacteria.” JOURNAL OF APPLIED MICROBIOLOGY 109.5 (2010): 1579–1590. Print.
@article{1058086,
  abstract     = {Aims: This study aimed at isolating thermophilic bacteria that utilize cheap carbon substrates for the economically feasible production of poly(3-hydroxybutyrate), poly(3HB), at elevated temperatures. 
Methods and Results: Thermophilic bacteria were enriched from an aerobic organic waste treatment plant in Germany, and from hot springs in Egypt. Using the viable colony staining method for hydrophobic cellular inclusions with Nile red in mineral salts medium (MSM) containing different carbon sources, six Gram-negative bacteria were isolated. Under the cultivation conditions used in this study, strains MW9, MW11, MW12, MW13 and MW14 formed stable star-shaped cell-aggregates (SSCAs) during growth; only strain MW10 consisted of free-living rod-shaped cells. The phylogenetic relationships of the strains as derived from 16S rRNA gene sequence comparisons revealed them as members of the Alphaproteobacteria. The 16S rRNA gene sequences of the isolates were very similar ({\textrangle} 99\% similarity) and exhibited similarities ranging from 93 to 99\% with the most closely related species that were Chelatococcus daeguensis, Chelatococcus sambhunathii,Chelatococcus asaccharovorans, Bosea minatitlanensis, Bosea thiooxidans and Methylobacterium lusitanum. Strains MW9, MW10, MW13 and MW14 grew optimally in MSM with glucose, whereas strains MW11 and MW12 preferred glycerol as sole carbon source for growth and poly(3HB) accumulation. The highest cell density and highest poly(3HB) content attained were 4 center dot 8 g l-l (cell dry weight) and 73\% (w/w), respectively. Cells of all strains grew at temperatures between 37 and 55 degrees C with the optimum growth at 50 degrees C. 
Conclusions: New PHA-accumulating thermophilic bacterial strains were isolated and characterized to produce poly(3HB) from glucose or glycerol in MSM at 50 degrees C. SSCAs formation was reported during growth. 
Significance and Impact of the Study: To the best of our knowledge, this is the first report on the formation of SSCAs by PHA-accumulating bacteria and also by thermophilic bacteria. PHA-producing thermophiles can significantly reduce the costs of fermentative PHA production.},
  author       = {Ibrahim, Mohammad and Willems, Anne and Steinb{\"u}chel, Alexander},
  issn         = {1364-5072},
  journal      = {JOURNAL OF APPLIED MICROBIOLOGY},
  keyword      = {BACILLUS SP INT005,thermophiles,SP-NOV.,POLY(3-HYDROXYBUTYRATE) PRODUCTION,POLYHYDROXYALKANOIC ACIDS,BIOCHEMICAL-PROPERTIES,MICROBIAL-DEGRADATION,THERMUS-THERMOPHILUS,WASTE-WATER,GEN.-NOV.,NILE RED,star-shaped cell-aggregates,poly(3HB) accumulation,Chelatococcus sp,16S rDNA},
  language     = {eng},
  number       = {5},
  pages        = {1579--1590},
  title        = {Isolation and characterization of new poly(3HB)-accumulating star-shaped cell-aggregates-forming thermophilic bacteria},
  url          = {http://dx.doi.org/10.1111/j.1365-2672.2010.04786.x},
  volume       = {109},
  year         = {2010},
}

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