Proizvodnja i karakterizacija poli(3-hidroksibutirata) iz oleinske kiseline s pomoću bakterije Ralstonia eutropha

The aim of this research is to investigate the influence of oleic acid concentration on the cell growth and the physical properties of the polymer formed by cultures of Ralstonia eutropha in mineral medium. Cells were cultivated in Erlenmeyer flasks with 300 mL of mineral medium, containing glucose and fructose as a carbon source (30 g/L) and ammonium sulphate (5.0 g/L) as a nitrogen source. Oleic acid was added as nutritional supplement in different concentrations (0, 0.3, 0.9, 1.5 and 3.0 g/L) and the cells were incubated at 30 °C and 150 rpm. The films prepared by casting were evaluated by X-ray diffraction, thermogravimetry and differential scanning calorimetry. These results indicate that the increase of oleic acid concentrations leads to a higher specific growth rate and cell productivity. The characterization of the films revealed that the increase of the concentration of oleic acid from 0 to 1.5 g/L has no influence on thermal behaviour and crystallinity degree. However, the thermal stability, melting temperature, glass transition temperatures and crystallinity degree decreased when 3.0 g/L of oleic acid were used.Svrha je ovoga istraživanja bila ispitati utjecaj koncentracije oleinske kiseline na rast stanica i fizikalna svojstva polimera koji proizvodi bakterija Ralstonia eutropha na mineralnoj podlozi. Stanice su uzgojene u Erlenmeyerovim tikvicama s 300 mL mineralne podloge, uz dodatak glukoze i fruktoze kao izvora ugljika (30 g/L) i amonijeva sulfata (5,0 g/L) kao izvora dušika. Kao dopunsko hranjivo dodana je oleinska kiselina u različitim koncentracijama (0; 0,3; 0,9; 1,5 i 3,0 g/L), nakon čega su stanice uzgojene na 30 °C pri 150 rpm. Lijevanjem dobiveni filmovi ispitani su difrakcijom x-zraka, termogravimetrijom i diferencijalnom skenirajućom kalorimetrijom. Rezultati su pokazali da je porast koncentracije oleinske kiseline uzrokovao povećanje specifične brzine rasta i broja stanica. Karakterizacijom filmova otkriveno je da koncentracija oleinske kiseline od 0 do 1,5 g/L nije utjecala na toplinska svojstva i stupanj kristalizacije. Međutim, toplinska stabilnost, talište, staklište i stupanj kristalizacije smanjili su se s povećanjem koncentracije oleinske kiseline iznad 3,0 g/L

Production and Characterization of Poly(3-Hydroxybutyrate) from Oleic Acid by Ralstonia eutropha

The aim of this research is to investigate the influence of oleic acid concentration on the cell growth and the physical properties of the polymer formed by cultures of Ralstonia eutropha in mineral medium. Cells were cultivated in Erlenmeyer flasks with 300 mL of mineral medium, containing glucose and fructose as a carbon source (30 g/L) and ammonium sulphate (5.0 g/L) as a nitrogen source. Oleic acid was added as nutritional supplement in different concentrations (0, 0.3, 0.9, 1.5 and 3.0 g/L) and the cells were incubated at 30 °C and 150 rpm. The films prepared by casting were evaluated by X-ray diffraction, thermogravimetry and differential scanning calorimetry. These results indicate that the increase of oleic acid concentrations leads to a higher specific growth rate and cell productivity. The characterization of the films revealed that the increase of the concentration of oleic acid from 0 to 1.5 g/L has no influence on thermal behaviour and crystallinity degree. However, the thermal stability, melting temperature, glass transition temperatures and crystallinity degree decreased when 3.0 g/L of oleic acid were used