Metals and linear alkylbenzene sulphonate as inhibitors of the algae Pseudokirchneriella subcapitata acid phosphatase activity.

Sewage sludge applied to soils as a fertilizer often contains metals and linear alkylbenzene sulphonate (LAS) as contaminants. These pollutants can be transported to the aquatic environment where they can alter the phosphatase activity in living organisms. The acid phosphatase of algae plays important roles in metabolism such as decomposing organic phosphate into free phosphate and autophagic digestive processes. The order of in vitro inhi- bition of Pseudokirchneriella subcapitata acid phosphatase at the highest concentration tested was LAS[Hg2? = Al 3?[Se4? = Pb2?[Cd2?. A non-competitive inhibi- tion mechanism was obtained for Hg2? (Ki = 0.040 mM) and a competitive inhibition for LAS (Ki = 0.007 mM). In vivo studies with treated algae cultures showed that the inhibition of specific activity was observed in algae exposed during 7 days, in contrast to short term (24 h) treatments with both these chemicals. Our results suggest that the inhibition parameters in vitro did not markedly differ between the two chemicals. On the other hand, in vivo evaluations showed strong differences between both pollu- tants regarding the concentration values and the degree of response.

Influence of Pseudomonas putida AF7 inoculation on soil enzymes.

There has been some concern about the environmental impact of microbial agents. Pseudomonas may be used as bioremediator and as biopesticide. In this study, we report the use of soil enzyme assays as biological indicator of possible negative effects in soil functioning after the P. putida AF7 inoculation. For that, P. putida AF7 was originally isolated from the rizosphere of rice and was inoculated on three soil types: Rhodic Hapludox (RH), Typic Hapludox (TH); and Arenic Hapludult (AH). The acid phosphatase, b-glucosidase and protease enzymes activities were measured for three period of evaluation (7, 14 and 21 days). In general, the enzymatic activities pre- sented variation among the tested soils. The highest activities of b-glucosidase and acid phosphatase were observed in the RH and AH soils, while the protease activity was higher in the TH soil. Also, the soil charac- teristics were measured for each plot. The activity of enzymes from the carbon cycle was positively correlated with the N and the P and the enzyme from the nitrogen cycle was negatively correlated with N and C.org. The presented data indicate that soil biochemical properties can be an useful tool for use as an indicator of soil perturba- tions by microbial inoculation in a risk assessment.

Microwave-assisted solvent extraction and analysis of shikimic acid from plant tissues.

A better method for determination of shikimate in plant tissues is needed to monitor exposure of plants to the herbicide glyphosate [N-(phosphonomethyl)glycine] and to screen the plant kingdom for high levels of this valuable phytochemical precursor to the pharmaceutical oseltamivir. A simple, rapid, and efficient method using microwave-assisted extraction (MWAE) with water as the extraction solvent was developed for the determination of shikimic acid in plant tissues. High performance liquid chromatography was used for the separation of shikimic acid, and chromatographic data were acquired using photodiode array detection. This MWAE technique was successful in recovering shikimic acid from a series of fortified plant tissues at more than 90% efficiency with an interference-free chromatogram. This allowed the use of lower amounts of reagents and organic solvents, reducing the use of toxic and/or hazardous chemicals, as compared to currently used methodologies. The method was used to determine the level of endogenous shikimic acid in several species of Brachiaria and sugarcane (Saccharum officinarum) and on B. decumbens and soybean (Glycine max) after treatment with glyphosate. The method was sensitive, rapid and reliable in all cases.

Artificial tritrophic exposure system for environmental risk analysis on aphidophagous predators.

2016

Proposta de validação de testes de biopesticidas e biorremediadores em mamíferos.

2008