Influence of metal ions and organic carbons on denitrification activity of the halotolerant bacterium, Paracoccus pantotrophus P16 a strain from shrimp pond

The effect of metal ions, ferric ion (Fe3+) and molybdenum ion (Mo6+) on the denitrification process of Paracoccus pantotrophus P16 grown under saline conditions was investigated. Results revealed that the dosages of added Fe3+ and Mo6+ significantly accelerated nitrate utilization and nitrite accumulation. Enzymatic studies revealed that the membrane-bound nitrate reductase and the periplasmic nitrite reductase had activities of 998 +/- 28 and 373 +/- 18 nmol (mg protein)-1 min-1, respectively after growing Paracoccus pantotrophus P16 in medium supplemented with 1.5 micron M Fe3+. If provided with 1.5 micron M Fe3+and 2.4 micron M Mo6+, the membrane-bound nitrate reductase activity increased to 6,223 +/- 502 nmol (mg protein)-1 min-1 and the periplasmic nitrite reductase was 344 +/- 20 nmol (mg protein)-1 min-1. The results indicated that an addition of Fe3+ and Mo6+ led to an overstimulation of nitrate reductase activity as compared with nitrite reductase activity. When glucose was supplied, the minimal ratio of carbon per nitrate (C/N) was 2.31 mg C/mg NO3--N with denitrification yield of 0.45 g NO3--N/g C. Addition of ethanol instead of glucose, the minimal ratio of C/N was 1.15 mg C/mg NO3--N with denitrification yield of 1.08 g NO3--N/g C.

Brine shrimp cytotoxicity of some medicinal plants Belongs to Lamiaceae, Asteracea, Rosaceae and Boraginaceae Families

In this report, we evaluated the cytotoxic activity of the hexane, ethyl acetate, methanol and aqueous methanol extracts of the aerial parts of some species belongs to Lamiaceae, Boraginaceae, Asteraceae and Rosaceae families. In order to examine the cytotoxicity of the plant extracts, Brine Shrimp Cytotoxicity Assay was used against Artemia salina larva. Results showed that Scutellaria Tornefortii indicated cytotoxic activity against the larva of Artemia salina. The minimum lethal concentration of its aqueous methanol extract, as the most effective extract, was 6 g/ml compared to berberine hydrochloride as the positive control [LC[50]=26 microg/ml]. EtOAc extract of Rubus hyrcanus was also a potent cytotoxic extract [LC[50]=28 microg/ml]. In addition to those mentioned plants, Echium amoenum, Onosma bulbotrichum, Stachys byzanthina and Rubus discolor could be the potential sources of cytotoxic components. Some of the medicinal plants, growing widely in north part of Iran, are effective against the larvae of A. salina, so they could be a promising source of anti-cancer and anti-tumor compounds