Effects on C-phycocyanin content of Arthrospira (Spirulina) platensis of culture medium containing geothermal water.

This research aimed to compare effects on product quality and algal growth of inoculation ratio of Arthrospira platensis in the culture medium containing 20% geothermal water. A. platensis was inoculated at the ratio of 1/6, 1/10, and 1/20 of nutrient medium volume (2500 mL). The experiment medium was prepared with 20% geothermal water and 80% distilled water. Schlösser medium, 100% geothermal water medium, and 100% distilled water were used as the control group. At the end of the experiment, Spirulina biomass was obtained by filtration through 80-micron plankton cloth and freeze-dried at -60 °C. Increasing inoculation density shortened the culture time and increased the growth rate compared to the other groups. The best growth among the experimental groups was obtained in a 1/6 ratio inoculated Spirulina group in a 20% geothermal water medium. Among the experimental groups, dry biomass was obtained in the Spirulina group inoculated at 1/6 in only 20% geothermal water medium. The optical density value was 0.989 (A750), and the biomass yield was 0.476 g/L in the experimental group, the highest among the Schlösser groups was 1.259 (A750), and the biomass yield was 0.928 g/L. The most efficient growth and phycocyanin content was determined in the 1/6 inoculated groups. The phycocyanin content in the experimental group was found in 22.49%, and the purity rate was 2.24. In control groups, 3.73 purity and 28.62% phycocyanin were determined in the Schlösser medium. While 48.42% protein was detected in the geothermal water group, 61.64% was obtained with the Schlösser medium.

Biosorption of Cu2+ by Pseudomonas putida Immobilized on Loofa Sponge (Luffa cylindrica L.)

Cu2+ contaminated areas pose serious health risk for the living organisms. In this study, the biosorption of Cu2+ by Pseudomonas putida immobilized on loofa sponge (Luffa cylindrica L.) was investigated. Effects of the particle size of loofa sponge, initial pH, temperature, initial Cu2+ concentration and the stirring speed on the adsorption of Cu2+ were examined. Optimum conditions were determined as follows: loofa sponge particle size is 0.42 - 0.85 mm, initial pH is 5.0, temperature is 30 °C, initial Cu2+ concentration is 25 mg/l, and stirring speed is 130 rpm. According to the results of kinetic calculations, Qmax and ro values were determined as 0.394 mg/g and 0.077 mg/g.min for P. putida immobilized on loofa sponge, respectively, while they were found to be 0.096 mg/g and 0.052 mg/g.min for the loofa sponge only. It is thought that Cu2+ can be removed effectively from the wastewaters by using P. putida immobilized on loofa sponge.

Antioxidant activities of pomegranate peel methanolic and water extracts by in vitro methods

In this study, the antioxidant activities of pomegranate (Punica granatum) peel extracts were investigated using different antioxidant activity methods. The antioxidant activities of extracts prepared at different concentrations (100-1000 μg/ml) were compared with α-tocopherol, ascorbic acid, BHT, and BHA standards. The methanol extract of peels had the highest yield (45.5%). Chelating activities (Fe2+) of methanol extract at 100-1000 μg/ml concentrations ranged between 16.63 and 46.45%. However, the chelating activities of all test extracts were lower than the standards. The reducing power of all extracts increased concentration-dependent. DPPH˙˙ radical scavenging activity of methanol extract varied in the range of 18.53 to 88.75%. The highest percentage inhibition of linoleic acid oxidation was found in 250 μg/ml concentrations. Trolox equivalent (TEs) antioxidant capacity values of methanol extract ranged from 3.09 to 15.27 µM TEs 10 g-1. It was determined that methanol extract showed a dose-dependent inhibition of the antioxidant activities.