Polyhydroxyalkanoates are microbial polyesters which are considered being biological alternatives to petrochemical polymers. Extremophiles, such as thermophilic PHA producers, hold promise to improve competitiveness of PHA production process. Therefore, this work aimed at isolation of new strains, which could produce PHA under elevated temperature. Since traditional Nile red staining of colonies provided false positive results in thermophiles, we developed a novel strategy of enriching microbial consortia by PHA producers. This so called "osmoselective strategy" is based on application of osmotic challenge by sudden exposition of the mixed microbial culture to hypertonic and subsequently to hypotonic conditions; moreover, this strategy relies on the fact that PHA protect bacteria from negative effects of rapid fluctuations in osmotic pressure. In combination with fast and reliable ATR-FTIR inspection of selected colonies for presence of PHA, we were able to isolate several promising thermophilic or thermotolerant PHA producing strains belonging to the genera Bacillus, Aneurinibacillus and Chelatococcus, which indeed deserves further investigation to evaluate their potential for industrial production of PHA.
- MeSH
- Alphaproteobacteria izolace a purifikace MeSH
- Bacillales izolace a purifikace MeSH
- Bacillus izolace a purifikace MeSH
- Bacteria izolace a purifikace MeSH
- bioreaktory MeSH
- DNA bakterií MeSH
- fermentace MeSH
- mikrobiální společenstva * MeSH
- osmóza MeSH
- polyhydroxyalkanoáty chemie MeSH
- sekvence nukleotidů MeSH
- termotolerance MeSH
- vysoká teplota MeSH
- Publikační typ
- časopisecké články MeSH
The aim of this work was to investigate the thermophilic bacterium Schelegelella thermodepolymerans DSM 15344 in terms of its polyhydroxyalkanoates (PHA) biosynthesis capacity. The bacterium is capable of converting various sugars into PHA with the optimal growth temperature of 55 °C; therefore, the process of PHA biosynthesis could be robust against contamination. Surprisingly, the highest yield was gained on xylose. Results suggested that S. thermodepolymerans possess unique xylose metabolism since xylose is utilized preferentially with the highest consumption rate as compared to other sugars. In the genome of S. thermodepolymerans DSM 15344, a unique putative xyl operon consisting of genes responsible for xylose utilization and also for its transport was identified, which is a unique feature among PHA producers. The bacterium is capable of biosynthesis of copolymers containing 3-hydroxybutyrate and also 3-hydroxyvalerate subunits. Hence, S.thermodepolymerans seems to be promising candidate for PHA production from xylose rich substrates.
- MeSH
- Comamonadaceae * MeSH
- kyselina 3-hydroxymáselná MeSH
- polyhydroxyalkanoáty * MeSH
- xylosa MeSH
- Publikační typ
- časopisecké články MeSH
The aim of this work was to study the potential of selected Halomonas species for conversion of waste frying oil into polyhydroxyalkanoates (PHA). In total nine Halomonas strains were experimentally screened for their capability of PHA production. Among them, Halomonas neptunia and Halomonas hydrothermalis were identified as potent PHA producers. Initial concentration of NaCl was identified as parameter influencing PHA yields as well as molecular weight of the polymer. In addition, H. hydrothermalis was capable of biosynthesis of a copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate P(3HB-co-3HV). When valerate was utilized as a precursor, the 3HV fraction in the copolymer reached high values of 50.15 mol.%. PHA production on lipid substrates by Halomonas has not been reported so far. Bearing in mind all the positive aspects of employing extremophiles in industrial biotechnology, H. hydrothermalis seems to be a very interesting halophilic strain for production of PHA using lipid substrates.
- MeSH
- biotechnologie MeSH
- Halomonas * MeSH
- kyselina 3-hydroxymáselná MeSH
- polyestery MeSH
- polyhydroxyalkanoáty * MeSH
- Publikační typ
- časopisecké články MeSH
This work explores molecular, morphological as well as biotechnological features of the highly promising polyhydroxyalkanoates (PHA) producer Halomonas halophila. Unlike many other halophiles, this bacterium does not require expensive complex media components and it is capable to accumulate high intracellular poly(3-hydroxybutyrate) (PHB) fractions up to 82% of cell dry mass. Most remarkably, regulating the concentration of NaCl apart from PHB yields influences also the polymer's molecular mass and polydispersity. The bacterium metabolizes various carbohydrates including sugars predominant in lignocelluloses and other inexpensive substrates. Therefore, the bacterium was employed for PHB production on hydrolysates of cheese whey, spent coffee grounds, sawdust and corn stover, which were hydrolyzed by HCl; required salinity of cultivation media was set up during neutralization by NaOH. The bacterium was capable to use all the tested hydrolysates as well as sugar beet molasses for PHB biosynthesis, indicating its potential for industrial PHB production.
- MeSH
- Halomonas * MeSH
- hydroxybutyráty * MeSH
- kyselina 3-hydroxymáselná MeSH
- polyestery * MeSH
- Publikační typ
- časopisecké články MeSH
Polyhydroxyalkanoates (PHA) are polyesters accumulated by numerous prokaryotes as storage materials; they attract attention as "green" alternatives to petrochemical plastics. Recent research has demonstrated that their biological role goes beyong their storage function, since they presence in cytoplasm enhances stress resistance of microorganisms. To address these complex functions, this review summarizes the protective effects of PHA for microrganisms; the involvement of PHA in stress resistance is discussed also from a praxis-oriented perspective. The review discourses the controlled application of stress to improve PHA productivity. Also the manifold advantages of using stress adapted microbes - extremophiles as PHA producers are discussed.
- MeSH
- biodegradace * MeSH
- biotechnologie metody MeSH
- fyziologický stres MeSH
- fyziologie bakterií * MeSH
- mikrobiální společenstva MeSH
- odpad tekutý - odstraňování metody MeSH
- osmotický tlak MeSH
- polyhydroxyalkanoáty metabolismus MeSH
- zemědělství metody MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
