Effect of macronutrients and of anaerobic digestate on the heterotrophic cultivation of Chlorella vulgaris grown with glycerol.

The aim of this work was to investigate the kinetics of the heterotrophic growth of Chlorella vulgaris as a means of producing bio-oil for biodiesel production. Glycerol was used as the sole organic carbon substrate. Anaerobic digestate from a local plant was used to examine its effect on the kinetics and the protein and lipid content of the biomass. The effect of the initial carbon and nitrogen concentrations on the carbon uptake rate was studied independently. In the one set of five experiments, the organic carbon in the form of glycerol varied from 0.27 to 5.36 g L-1, while the concentration of atomic nitrogen was held constant and equal to 45.4 mg L-1. The Co/No ratio varied from 6 to 118.1. In the second set, also of five experiments, the organic carbon was held constant and equal to 3.3 g L-1 and atomic nitrogen varied from 22.7 to 450 mg L-1. The Co/No ratio varied from 7.3 to 145.4. In the third set of experiments, anaerobic digestate was added in increasing amounts into the culture media from 4 to 16%. It was found that the carbon uptake rate as well as the lipid and protein content depended on the Co/No ratio. Increasing ratios of Co/No led to higher carbon uptake rates, higher lipid content, and lower protein content. The initial nitrogen concentration was also found to affect the growth rate of C. vulgaris. The addition of anaerobic digestate did not affect appreciably the protein and lipid content of the biomass, while the addition of anaerobic digestate up to 16% in the culture medium increased the carbon uptake rate by about 24%.

Novel feed including bioactive compounds from winery wastes improved broilers' redox status in blood and tissues of vital organs.

Currently, there is a great interest in the production of animal feed with antioxidant activity. The aim of this study was to examine the potential antioxidant effects of a feed supplemented with grape pomace (GP), a winery by-product with high environmental load, in chickens. Broilers of 15 days post birth were separated into two groups fed either with standard diet or with diet supplemented with GP for 35 days. Blood and tissues collections were performed after feeding for 15 and 35 days with the experimental diet (i.e. at 30 and 50 days post birth). Free radical toxicity markers, namely thiobarbituric acid reactive substances, protein carbonyls, total antioxidant capacity, reduced glutathione, catalase activity and rate of H2O2 decomposition were determined in blood and tissues of vital organs. The results indicated that feed supplemented with GP decreased oxidative stress-induced toxic effects and improved chickens' redox status, and so it may also improve their wellness and productivity. On the other hand, this exploitation of GP may solve problems of environmental pollution in areas with wineries.

The Effects of an Olive Fruit Polyphenol-Enriched Yogurt on Body Composition, Blood Redox Status, Physiological and Metabolic Parameters and Yogurt Microflora.

In the present study we investigated the effects of an olive polyphenol-enriched yogurt on yogurt microflora, as well as hematological, physiological and metabolic parameters, blood redox status and body composition. In a randomized double-blind, crossover design, 16 (6 men, 10 women) nonsmoking volunteers with non-declared pathology consumed either 400 g of olive fruit polyphenol-enriched yogurt with 50 mg of encapsulated olive polyphenols (experimental condition-EC) or 400 g of plain yogurt (control condition-CC) every day for two weeks. Physiological measurements and blood collection were performed before and after two weeks of each condition. The results showed that body weight, body mass index, hip circumference and systolic blood pressure decreased significantly (p < 0.05) following the two-week consumption of yogurt regardless of condition. A tendency towards significance for decreased levels of low density lipoprotein (LDL) cholesterol (p = 0.06) and thiobarbituric acid reactive substances (p < 0.05) following two weeks of polyphenol-enriched yogurt consumption was observed. The population of lactic acid bacteria (LAB) and production of lactate in yogurt were significantly enhanced after addition of olive polyphenols, contrary to the population of yeasts and molds. The results indicate that consumption of the polyphenol-enriched yogurt may help individuals with non-declared pathology reduce body weight, blood pressure, LDL cholesterol levels and lipid peroxidation, and promote growth of beneficial LAB.

Assessment of the redox status in patients with metabolic syndrome and type 2 diabetes reveals great variations.

The aim of the present study was to examine the effectiveness of a new redox status marker, the static oxidation reduction potential (sORP), for assessing oxidative stress in 75 patients with metabolic syndrome (MetS) and type 2 diabetes (T2D). A total of 35 normal subjects were used as the controls. Moreover, conventional markers of oxidative stress were assessed, such as thiobarbituric acid reactive substances (TBARS), protein carbonyls, the total antioxidant capacity in plasma, glutathione (GSH) levels and catalase (CAT) activity in erythrocytes. The results revealed that sORP was significantly higher (by 13.4%) in the patients with MetS and T2D compared to the controls, indicating an increase in oxidative stress. This finding was also supported by the significantly lower levels (by 27.7%) of GSH and the higher levels (by 23.3%) of CAT activity in the patients with MetS and T2D compared to the controls. Moreover, our results indicated a great variation in oxidative stress markers between the different patients with MetS and T2D, particarly as regards the GSH levels. Thus, the patients with MetS and T2D were divided into 2 subgroups, one with low GSH levels (n=31; GSH <3 µmol/g Hb) and another with high GSH levels (n=35; GSH >4 µmol/g Hb). The comparison of the markers between the 2 subgroups indicated that in the low GSH group, the GSH levels were significantly lower (by 51.7 and 52.9%) than those in the high GSH group and the controls, respectively. Furthermore, sORP in the low GSH group was significantly higher (by 8.1%) compared to the high GSH group, suggesting its sensitivity for assessing oxidative stress in patients wtih MetS and T2D. Moreover, this variation in oxidative stress levels between the different patients with T2D suggests that the assessment of the redox status may be important in prediabetic conditions, since there is evidence indicating that differences in the redox status in pre-diabetes may result in different outcomes.

Variations in oxidative stress markers in elite basketball players at the beginning and end of a season.

The aim of the present study was to examine the changes occuring in the redox status in male basketball players at the beginning and end of a highly competitive season. For this purpose, the redox status of 14 professional athletes of a European basketball club was examined at 2 different time points, at the beginning (phase 1) and at the end of the season (phase 2). The redox status was assessed in blood using conventional oxidative stress markers, such as thiobarbituric acid reactive substances (TBARS), protein carbonyls (CARB) and the total antioxidant capacity (TAC) in plasma, as well as glutathione (GSH) levels and catalase (CAT) activity in erythrocytes. Moreover, a new static oxidation-reduction potential marker (sORP) was assessed in plasma. Our results revealed that sORP was significantly increased by 9.6% and GSH levels were significantly decreased by 35.0% at phase 2 compared to phase 1, indicating the induction of oxidative stress due to excessive exercise. Moreover, TAC was significantly increased by 12.9% at phase 2 compared to phase 1, indicating the activation of adaptive responses for counteracting oxidative stress. The CARB and TBARS levels were not significantly altered between the 2 phases, although there was a significant correlation (r=0.798) between the sORP and CARB levels. Furthermore, the variations in these markers between athletes were examined. We found that 3 markers exhibited a similar response between athletes, that is, sORP was increased in all 14 athletes, TAC was increased in 13 and the GSH levels were decreased in 14. However, the other 3 markers (i.e., TBARS, CARB and CAT) exhibited marked variations between the athletes, suggesting that the optimal approach with which to counteract (e.g., antioxidant supplementation) the observed increase in oxidative stress is the individualized examination of the redox status of athletes using a series of markers. This would allow the identification of athletes affected by severe oxidative stress and inflammation, and would thus indicate when necessary intervention measures are required to improve their health and performance.