Predicting chemical concentration effects on transformation rates of dissolved organics by complex microbial assemblages

Protective Effect of the Hexanic Extract of Eryngium carlinae Inflorescences In Vitro, in Yeast, and in Streptozotocin-Induced Diabetic Male Rats

In the present study, we investigated the composition and antioxidant activity of the hexanic extract of Eryngium carlinae inflorescences by employing in vitro assays to measure antioxidant capacity and 2,2-diphenyl-1-picrylhydrazyl scavenging activity. We also applied the hexanic extract to Saccharomyces cerevisiae, under hydrogen peroxide-induced stress. Finally, we tested the extract in male Wistar rats with and without streptozotocin-induced diabetes. The compounds in the hexanic extract were analyzed by gas-chromatography-mass spectrometry, which revealed mainly terpenes and sesquiterpenes, including (Z)β-farnesene (38.79%), β-pinene (17.53%), calamene (13.3%), and α-farnesene (10.38%). In vitro and in S. cerevisiae, the extract possessed antioxidant activity at different concentrations, compared to ascorbic acid (positive control). In normoglycemic and hyperglycemic rats, oral administration of 30 mg/kg of the extract reduced blood glucose levels; lipid peroxidation in liver, kidney and brain; protein carbonylation; and reactive oxygen species (ROS) production. It also increased catalase activity in the brain, kidneys and liver. These findings show that this hexanic extract of E. carlinae inflorescences possessed antioxidant properties.

Environmental aspects of PAH biodegradation

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants, some of which are on the US Environmental Protection Agency priority pollutant list. Consequently, timely clean-up of contaminated sites is important. The lower-mol-wt PAHs are amenable to bioremediation; however, higher-mol-wt PAHs seem to be recalcitrant to microbial degradation. The rates of biodegradation of PAHs are highly variable and are dependent not only on PAH structure, but also on the physicochemical parameters of the site as well as the number and types of microorganisms present. PAHs sorb to organic matter in soils and sediments, and the rate of their desorption strongly influences the rate at which microorganisms can degrade the pollutants. Much of the current PAH research focuses on techniques to enhance the bioavailability and, therefore, the degradation rates of PAHs at polluted sites. Degradation products of PAHs are, however, not necessarily less toxic than the parent compounds. Therefore, toxicity assays need to be incorporated into the procedures used to monitor the effectiveness of PAH bioremediation. In addition, this article highlights areas of PAH research that require further investigation.

A simple method for quantifying activity and survival of microorganisms involved in bioremediation processes

We have developed a substrate-induced growth response (SIGR) method for quantifying activity and population dynamics of microorganisms involved in bioremediation processes in soil and bioreactors. The biomass of organisms that can mineralize a given chemical can be estimated based on the concentration of that chemical needed to induce the growth of the standing population. Estimates of population size are obtained by using nonlinear regression techniques to fit a simple model of microbial population dynamics to biodegradation curves. Using this approach we obtain estimates of values for parameters such as initial population size and growth rate of organisms carrying out biodegradative processes. Our approach was validated by comparing model parameter estimates with independent estimates of the same parameters from the same bioremediation systems. Examples studied include pentachlorophenol degraders introduced into soil and 2,4-dinitrophenol degrading organisms in a bioreactor.