Search

Microalgae and their potential for food supplementation are a growing trend in modern society. Whole microalgal biomass and their extracts are rich in nutrients which give various health benefits. To further improve their characteristics as food supplements a co-cultivation with probiotic strains emerged as a new innovative way to increase nutrititional value. In order to increase probiotic strain acitivites, algae are usually added in powder form to cultivating broth. In this study, we performed co-cultivation of probiotic bacteria and viable microalga Chlorella vulgaris. Our main goal was to investigate if this approach can benefit to both organisms. We focused on optimization of growth conditions, examing inoculation ratio, temperatures, culturing volumes and media in correlation with biomass accumulation. Determination of C. vulgaris biomass composition has been performed using Nile Red (NR) method with flourescence microscopy for lipid accumulation ; spectrophotometry for pigments and Lowry method for protein yield. Metabolite products synthesized and released in culture medium, as well as metabolites embedded in biomass composition, were analysed using quadrupole time-of-flight (q-TOF) mass spectrometry revealing production of new compounds. Results of these comprehensive analysis will be presented.

Spirulina sp. is a widely cultivated cyanobacteria which contains a high amount of bioactive compounds with health-promoting effects and remarkable antioxidant activity due to the abundant presence of polyphenols and carotenoids. The effect of different drying temperatures (room temperature, 40, 50, 60, 80, and 100°C) on the phenolic profile and biological activity of Spirulina sp. was investigated. Samples were dried at various temperatures, extracted and then fractioned. Antioxidant activity of methanolic (F3) and dichloromethane (F4) fractions was evaluated using ABTS, FRAP, ORAC and DPPH assays. To determine the toxicity potential of prepared fractions, zebrafish embryotoxicity test was performed [2]. Phenolic compounds in Spirulina sp. samples were identified using HPLC, while LC/ MS- Q-TOF screening was used to predict the most probable bioactivities, chemical classes and drug- likeness properties of examined compounds. According to antioxidative assays, F3 fraction had higher ABTS and FRAP activity, while F4 fraction had higher DPPH and ORAC activity. The F4 fraction dried at 50°C showed the highest antioxidant activity using DPPH (687.06 +/- 11.41 mg AAE/g fraction), while ABTS and FRAP assays showed high activity for F3 fractions dried at 25, 30 and 100°C. There was no negative impact on the survival of zebrafish embryos and larvae observed at concentrations lower than 0.02 mg/mL. The most abundant polyphenols were epicatechin, vanillic acid, caffeic acid, diosmin, thymol, apigenin, while the presence of 3 alkanolamines and 25 lipid-like molecules was revealed by QTOF analysis. High antioxidant activity was observed at lower temperatures can be related to the presence of carotenoids and chlorophyll. Antioxidant potential of sample dried at 100°C can be attributed to pigment derivatives. The optimal temperature for preservation of polyphenols was 50 °C. A strong correlation between structural class of detected compounds and highly predicted activities (cardiovascular, antiinflammatory, anticancer) has been observed. The results indicate that drying at a lower temperature retains phenols and other components and maintains high antioxidant activity. From the obtained results, it can be concluded that lower drying temperatures better influence the content of phenolic compounds and biological activity of Spirulina sp., when compared to higher temperatures.

Spirulina sp. is a widely cultivated cyanobacteria which contains a high amount of bioactive compounds with health-promoting effects and remarkable antioxidant activity due to the abundant presence of polyphenols and carotenoids. The effect of different drying temperatures (room temperature, 40, 50, 60, 80, and 100°C) on the phenolic profile and biological activity of Spirulina sp. was investigated. Samples were dried at various temperatures, extracted and then fractioned. Antioxidant activity of methanolic (F3) and dichloromethane (F4) fractions was evaluated using ABTS, FRAP, ORAC and DPPH assays. To determine the toxicity potential of prepared fractions, zebrafish embryotoxicity test was performed. Phenolic compounds in Spirulina sp. samples were identified using HPLC, while LC/ MS-Q-TOF screening was used to predict the most probable bioactivities, chemical classes and drug-likeness properties of examined compounds. According to antioxidative assays, F3 fraction had higher ABTS and FRAP activity, while F4 fraction had higher DPPH and ORAC activity. The F4 fraction dried at 50°C showed the highest antioxidant activity using DPPH (687.06 +/- 11.41 mg AAE/g fraction), while ABTS and FRAP assays showed high activity for F3 fractions dried at 25, 30 and 100°C. There was no negative impact on the survival of zebrafish embryos and larvae observed at concentrations lower than 0.02 mg/mL. The most abundant polyphenols were epicatechin, vanillic acid, caffeic acid, diosmin, thymol, apigenin, while the presence of 3 alkanolamines and 25 lipid-like molecules was revealed by QTOF analysis. High antioxidant activity observed at lower temperatures can be related to the presence of carotenoids and chlorophyll. Antioxidant potential of sample dried at 100°C can be attributed to pigment derivatives. The optimal temperature for preservation of polyphenols was 50°C. A strong correlation between structural class of detected compounds and highly predicted activities (cardiovascular, anti-inflammatory, anticancer) has been observed. The results indicate that drying at a lower temperature retains phenols and other components and maintains high antioxidant activity. It can also be concluded that lower drying temperatures better influence the content of phenolic compounds and biological activity of Spirulina sp., when compared to higher temperatures.

Spirulina sp. is a widely cultivated microalgae that contains numerous bioactive compounds with health-promoting properties. Phenolic profile and biological activity were investigated in regard to different drying temperatures (25, 40, 50, 60, 80, 100°C). Antioxidant activity (ABTS, FRAP, ORAC, DPPH) of methanolic (F3) and dichloromethane (F4) fractions was evaluated. To assess the toxicity of the fractions, zebrafishembryos were used. Phenolic compounds were identified using HPLC, while prediction of most probable bioactivities, chemical classes, and drug-likeness properties were made using LC/MS-Q-TOF. The F4 (50°C) showed the highest altioxidant activity using DPPH, while ABTS and FRAP showed high activity for F3 (25, 30 and 100°C). No negative impact on the survival of zebrafish was observed at concentrations lower than 0.02 mg/mL. Most abundant polyphenols were epicatechin, vanillic and caffeic acid, while the presence of alkanolamines and lipid-like molecules was revealed by LC/MS-Q-TOF. High antioxidant activity was observed at lower temperatures, due to the presence of carotenoids and chlorophylls, while for the sample dried at 100°C this can be attributed to pigment derivatives. Optimal temperature for preservation of polyphenols was 50°C. A strong correlation between structural class of detected compounds and highly predicted activities (cardiovascular, anti- inflammatory, anticancer) has been observed.

Arthrospira platensis is a promising and sustainable microalga characterized by easy growth without the need for herbicide or pesticide usage, and the possibility to utilize the whole microalgae without waste and harmful greenhouse gas emissions. It represents a valuable source of bioactive compounds with different health-promoting properties which make A. platensis an attractive ingredient for the formulation of eco-friendly cosmetics. As dehydration is one of the crucial production steps in the cosmetic, pharmaceutic, and food industries, the aim of this work was to investigate the influence of different drying temperatures on the chemical composition of A. platensis. Antioxidant activity of methanol: dichloromethane (1:1) extracts from differently dried (40, 50, 60, 80, and 100°C) samples were analyzed using 2, 2-diphenyl-1-picryl-hydrazyl (DPPH), reduction of the radical cation (ABTS), ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) assays. The influence of drying temperature on total protein, carbohydrate, pigment, and lipid content was evaluated, while gas chromatography was carried out to determine fatty acid composition. By implementing ABTS and DPPH methods, the highest antioxidant activity was observed for the sample dried at 40°C followed by 50 and 80°C dried samples with 1.5- and 2.5-fold lower activity (p

Uzgoj zelenih jednostaničnih algi poput Chlorella vulgaris ekološki je prihvatljiv i odrţiv proces. Sinteza različitih visokovrijednih proizvoda u ovim mikroalgama polje je interesa, a uspostavljanje ekonomski prihvatljivih bioprocesa i dalje je veliki izazov. Cilj ovoga rada bio je provesti fototrofni i miksotrofni uzgoj uz usporedbu sastava biomase dobivene tijekom uzgoja. Miksotrofni uzgoj doprinosi višim prinosima biomase te posljedično nakupljanja veće količine proizvoda od interesa. Maksimalni prinos biomase dobiven u ovom radu pri miksotrofnim uvjetima iznosio je 16, 79 g L-1 dok je produktivnost sinteze biomase sedamnaestog dana uzgoja iznosila 3, 48 g L-1 dan-1. Najzastupljenije makromolekule u biomasi C. vulgaris u fototrofnim i miksotrofnim uvjetima su proteini s udjelom većim od 40 %. Način uzgoja utječe na udio klorofila a i b u stanici. Kod fototrofnog uzgoja udio klorofila je i do deset puta veći nego u biomasi narasloj u miksotrofnim uvjetima uzgoja. Povećanjem molarnog omjera ugljika i dušika pri miksotrofnim uvjetima rasta udio ugljikohidrata i lipida u biomasi se povećao.

Due to the constant increase in energy consumption, the production of biofuels from renewable sources, such as lignocellulosic waste, has become more frequent in the last several decades. Lignocellulosic waste consists of cellulose, hemicellulose and lignin and the yeast S. cerevisiae is not able to ferment it directly. Therefore, lignocellulosic waste is usually hydrolysed to release compounds that can be used for fermentation. However, the pretreatment also generates compounds that act as growth and fermentation inhibitors such as acetic and levulinic acid and 2-furaldehyde. In this study, newly constructed intraspecies hybrid diploids, obtained by crossing natural S. cerevisiae isolates, showed higher resistance to acetic and levulinic acid. Selected strains were also transformed with replicative vectors overexpressing yeast genes (e.g. ATR1, CTA1, FLR1, YAP1, ZWF1) encoding proteins involved in a stress response and the overexpression of YAP1 gene further increased the resistance to inhibitors. Therefore, our results suggest that the construction of intraspecies hybrids coupled with genetic engineering is a promising approach for construction of new biotechnologically relevant yeast strains.