Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 3

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
Biosynthesis of biodegradable polymers polyhydroxyalkanotes (PHAs) have been studied extensively in wild type and genetically modified prokaryotic cells, however the content and structure of PHAs in wild type yeasts is not well documented. The purpose of this study was to screen yeast isolates collected from different ecosystems for their ability to accumulate PHAs. Identification of the isolates and characterization of PHAs produced by the positive isolates were investigated. One positive isolate (strain Y4) was identified by both API20C system and 18S rDNA sequencing. The data revealed that isolate Y4 belongs to the yeast genus Rhodotorula and exhibits 18S rDNA similarity value >99% to the species Rhodotorula minuta. Quantification of PHAs yield of strain Y4 in glucose, oleic acid and tween 60 containing medium for over a growth period of 96 h gave 2% of PHAs in biomass. The nature of produced PHAs was analyzed by infrared spectroscopy and nuclear magnetic resonance (¹H and ¹³C NMR) and found to contain polyhydroxybutyrate and polyhydroxyvalerate (PHBV).
Compared with conventional synthetic flocculants, bioflocculants has special advantages such as safety, strong effect, biodegradable and harmlessness to humans and the environment, so they may potentially be applied in drinking and wastewater treatment, downstream processing, and fermentation processes. To utilize bioflocculants widely in industrial fields, it is desirable to find various microorganisms with high bioflocculant-producing ability and improve the flocculating efficiency of the bioflocculant. In the present study, screening of new flocculant-producing microorganisms was carried out using samples collected from different Qatari ecosystems. The flocculating activity of the novel bioflocculants produced by isolated microorganisms was investigated. A total of 5 g/l Kaolin suspension was used to measure the flocculating activity. Isolated bioflocculant-producing bacteria were identified by 16S rDNA analysis, using PCR with universal primers. Comparative analysis of the 16S rDNA sequence (~550 bp) in the GenBank database revealed that these bacteria are related to the genus Bacillus. FT-IR spectrometry analysis of the extracted bioflocculants indicated the presence of carboxyl, hydroxyl and amino groups preferred for the flocculation process. Influences of pH and bioflocculant dosage on the flocculation were also examined. The maximum flocculating rates were observed at pH 7, 7 and 3 of the bioflocculants derived from strains QUST2, QUST6 and QUST9, respectively. However, 20.0 mg/l was the dose that gave the highest flocculating rate with all examined bioflocculants. The elemental analysis of examined bioflocculants revealed the mass proportion of C, H, N and S. Carbon and nitrogen contents of examined bioflocculants were in the range of 42-48% and 11-12%, respectively.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.