Effect of Different Sugar Sources on P. rhodozyma Y1654 Growth and Astaxanthin Production

O.N. Kanwugu¹*, S.A. Shatunova¹², T.V. Glukhareva¹³ and E.G. Kovaleva¹

¹Ural Federal University named after the first President of Russia B.N. Yeltsin, Institute of Chemical Engineering, Mira street 28, RU620002 Ekaterinburg, Russia
²University of Queensland, School of Chemistry and Molecular Bioscience, 68 Cooper Road, Brisbane City QLD 4072, Australia
³Postovsky Institute of Organic Synthesis, S. Kovalevskaya street 22, Akademicheskaya street 20, RU620990 Ekaterinburg, Russia
*Correspondence: nabayire@gmail.com

Abstract:

Phaffia rhodozyma (also known as Xanthophyllomyces dendrorhous) is one of the most promising natural sources of commercial astaxanthin. It has high growth rates, easy cultivation conditions and able to utilize different carbon substrates. This provides an opportunity to further lower production cost by using industrial waste such as molasses. This research therefore evaluates the growth dynamic and astaxanthin production of P. rhodozyma Y1654 growing on soy and sugar beet molasses-based media. Liquid growth media based on soy molasses (SM), sugar beet molasses (SBM) and glucose (control) as main sugar source with peptone and yeast extract supplementation were inoculated with 48 h old seed culture (grown in standard glucose media: 2.0% glucose, 1.0% peptone, 0.2% yeast extract) and incubated at 20 °C with stirring speed of 180 rpm for 7 days. Samples were taken daily throughout the study period to assess; cell count, dry cell weight (DCW) and amount of astaxanthin. Soy molasses-based media resulted in the highest biomass yield (7.7 g L^-1) followed by SBM (5.8 g L^-1). Generally, more than 90% of initial fermentable sugar was consumed at the end of the study. However, about 40% of total sugar in SM was unassimilable by P. rhodozyma Y1654. The highest astaxanthin yield was observed in the control media (77 μg g^-1 of DCW). Cultivation of P. rhodozyma Y1654 in SBM resulted in as much as twice (32.8 μg g^-1 of DCW) the astaxanthin yield of SM (12.4 μg g^-1 DCW). Molasses-based media are good for growth of P. rhodozyma Y1654 but for astaxanthin production, they need further optimization.

Key words:

agric-food wastes, astaxanthin, byproducts, carotenoids, microbial pigment, molasses, Xanthophyllomyces dendrorhous

Anaerobic co-fermentation of molasses and oil with straw pellets

V. Dubrovskis*, I. Plume and I. Straume

Latvia University of Life Sciences and Technologies, Faculty of Engineering, Institute of Energetics, Cakstes blvd. 5, LV3001 Jelgava, Latvia
*Correspondence: vilisd@inbox.lv

Abstract:

The average grain and straw production in Latvia is increasing in last decade. Straw is not always managed properly and its utilisation in biogas plants can be considered as an alternative. Straw is not the best feedstock for methane production, because it has high C/N ratio. Co-fermentation with other biomass with higher N content can improve the methane production. Purpose of investigation is to evaluate the wheat straw pellets biomass suitability for production of the methane and effect of its co-fermentation with molasses, fried sunflower oil and catalyst Metaferm. The anaerobic digestion process for biogas production was investigated in 0.75 L digesters, operated in batch mode at temperature 38 ± 1.0°C. The average biogas yield per unit of dry organic matter added from digestion of wheat straw pellets was 0.540 L g^-1_DOM and methane yield was 0.285 L g^-1_DOM. Average biogas yield from co-fermentation of wheat straw pellets and molasses was 0.777 L g^-1_DOM and methane yield was 0.408 L g^-1_DOM. Average biogas yield from fermentation of wheat straw pellets with 1ml Metaferm was 0.692 L g^-1_DOM and methane yield was 0.349 L g^-1_DOM. Average biogas yield from co-fermentation of wheat straw pellets and sunflowers oil was 1.041 L g^-1_DOM and methane yield was 0.639 L g^-1_DOM. All investigated biomasses can be used for methane production.

Key words: