AIM: This study aimed at unprecedented physical and chemical evaluation of the 'green plastics' polyhydroxyalkanoates (PHAs), in an extremely halotolerant Halomonas elongata strain 2FF under high-salt concentration. METHODS AND RESULTS: The investigated bacterial strain was isolated from the surface water of the hypersaline Fără Fund Lake. The 16S rRNA gene sequence phylogeny and phenotypic analysis indicated that the isolate belonged to H. elongata. PHA inclusions were observed by Sudan Black B, Nile Red staining, and transmission electron microscopy during growth at high salinity (10%, w/v, NaCl) on 1% (w/v) d-glucose. The produced polymer was quantitatively and qualitatively assessed using crotonic acid assay, elemental analysis, Fourier transform infrared and Raman spectroscopies. Additionally, X-ray powder diffraction, 1 H-NMR spectroscopy, and differential scanning calorimetry were applied. The investigations showed that the intracellular polymer was polyhydroxybutyrate (PHB) of which the strain produced up to 40 wt% of total cell dry weight after 48 h. The analysis of phaC gene from the isolated H. elongata strain indicated that the encoded PHA synthase belongs to Class I PHA synthase family. CONCLUSIONS: Overall, our investigations pointed out that the halotolerant H. elongata strain 2FF was capable to produce significant amounts of PHB from d-glucose, and PHAs from various carbon substrates at high-salt concentrations. SIGNIFICANCE AND IMPACT OF THE STUDY: The tested strain showed the ability for significant production of natural, biodegradable polymers under nutrient limitation and hypersaline conditions suggesting its potentiality for further metabolic and molecular investigations towards enhanced biopolymer production. Additionally, this study reports on the unprecedented use of Raman and XPRD techniques to investigate PHAs of an extremely halotolerant bacterium, thus expanding the repertoire of physical methods to study green plastics derived from extremophilic microorganisms.
- Klíčová slova
- Halomonas sp., green plastics, halotolerant bacteria, high salinity, nutrient limitation, polyhydroxybutyrate,
- MeSH
- biopolymery biosyntéza MeSH
- chlorid sodný metabolismus MeSH
- fylogeneze MeSH
- Halomonas genetika izolace a purifikace metabolismus MeSH
- jezera mikrobiologie MeSH
- polyhydroxyalkanoáty biosyntéza chemie MeSH
- RNA ribozomální 16S genetika MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Rumunsko MeSH
- Názvy látek
- biopolymery MeSH
- chlorid sodný MeSH
- polyhydroxyalkanoáty MeSH
- RNA ribozomální 16S MeSH
The kinetic study of Arthrospira platensis extracellular polymeric substances (EPS) production under different trophic modes-photoautotrophy (100 μmol photons m(-2) s(-1)), heterotrophy (1.5 g/L glucose), and mixotrophy (100 μmol photons m(-2) s(-1) and 1.5 g/L glucose)-was investigated. Under photoautotrophic and heterotrophic conditions, the maximum EPS production 219.61 ± 4.73 and 30.30 ± 1.97 mg/L, respectively, occurred during the stationary phase. Under a mixotrophic condition, the maximum EPS production (290.50 ± 2.21 mg/L) was observed during the early stationary phase. The highest specific EPS productivity (433.62 mg/g per day) was obtained under a photoautotrophic culture. The lowest specific EPS productivity (38.33 mg/g per day) was observed for the heterotrophic culture. The effects of glucose concentration, light intensity, and their interaction in mixotrophic culture on A. platensis EPS production were evaluated by means of 32 factorial design and response surface methodology. This design was carried out with a glucose concentration of 0.5, 1.5, and 2.5 g/L and at light levels of 50, 100, and 150 μmol photons m(-2) s(-1). Statistical analysis of the model demonstrated that EPS concentration and EPS yield were mainly influenced by glucose concentration and that conditions optimizing EPS concentration were dissimilar from those optimizing EPS yield. The highest maximum predicted EPS concentration (369.3 mg/L) was found at 150 μmol photons m(-2) s(-1) light intensity and 2.4 g/L glucose concentration, while the highest maximum predicted EPS yield (364.3 mg/g) was recorded at 115 μmol photons m(-2) s(-1) light intensity and 1.8 g/L glucose concentration.
- MeSH
- autotrofní procesy MeSH
- biopolymery biosyntéza MeSH
- fototrofní procesy MeSH
- glukosa metabolismus MeSH
- heterotrofní procesy MeSH
- sinice růst a vývoj metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- biopolymery MeSH
- glukosa MeSH
The main goal of this research was to investigate how different factors influence membrane fouling. The impact of the different concentrations of activated sludge and the amount of extracellular polymer substances (EPS) were monitored. Two pilot plants with submerged membrane modules (hollow fiber and flat sheet) were operated and the raw wastewater was used. Humic substances were identified as the major components of EPS in the activated sludge (more than 34%) in both pilot plants. As the basic constituent in permeate, humic substances were identified as the most dominant components in the effluent (61%) in both pilot plants. Conversely, proteins were mostly analyzed in permeate and supernatant below the detection limit. The total amount of EPS [mgg(-1) (VSS)] was similar for concentrations of activated sludge 6, 10 and 14 g L(-1). Carbohydrates were identified as the component of EPS which tends most to clog membranes.
- MeSH
- biopolymery biosyntéza MeSH
- bioznečištění * MeSH
- extracelulární prostor chemie MeSH
- kinetika MeSH
- kvartérní amoniové sloučeniny analýza MeSH
- membrány umělé * MeSH
- měření biologické spotřeby kyslíku MeSH
- odpad tekutý - odstraňování metody MeSH
- pilotní projekty MeSH
- rozpustnost MeSH
- tlak MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- biopolymery MeSH
- kvartérní amoniové sloučeniny MeSH
- membrány umělé * MeSH
