Essential oils and extracts of plants as biocides against microorganisms isolated from the ruins of the Roman city of Conímbriga (Portugal).

Biodeterioration of monumental complexes is in large part due to the proliferation of various microorganisms that attack the physical-chemical structures of support materials. Various conservation and restoration interventions use commercial biocides of synthetic origin, which exhibit some human and environmental toxicity and sometimes side effects on support materials. The main objective of this work is the assessment of new biocides obtained from endemic Mediterranean plants, to be used in the preservation of cultural heritage with the goal of contributing to the sustainable use of ecosystems and to the development of Mediterranean local communities.

Isolation, Identification, and Characterization of Phosphate-Solubilizing Bacteria from Tunisian Soils.

Soil microorganisms play an important role in maintaining natural ecological balance through active participation in carbon, nitrogen, sulfur, and phosphorous cycles. Phosphate-solubilizing bacteria (PSB) are of high importance in the rhizosphere, enhancing the solubilization of inorganic phosphorus complexes into soluble forms available for plant nutrition. The investigation of this species of bacteria is of major interest in agriculture, as they can be used as biofertilizers for crops.

Phosphorus removal by expanded clay--six years of pilot-scale constructed wetlands experience.

Constructed wetlands, which facilitate phosphorus removal via precipitation, adsorption, and biological assimilation, offer a promising appropriate technology for advanced treatment in wastewater treatment plants. Because adsorption and precipitation are pointed out as the major phosphorus-removal mechanisms, the selection of a medium with high phosphorus-sorption capacity is important to obtain a sustained phosphorus removal. The objective of this study was to evaluate two kinds of lightweight expanded clay aggregates (LWAs)--Filtralite NR and Filtralite MR (Maxit Group, Avelar, Portugal)--as substrates in constructed wetlands to improve phosphorus-removal performance.

Kinetics of L-tryptophan production from indole and L-serine catalyzed by whole cells with tryptophanase activity.

The essential amino acid L-tryptophan can be produced by a condensation reaction between indole and L-serine, catalyzed by whole cells of Escherichia coli B1t-7A with tryptophanase activity. The reaction was previously studied using soluble tryptophanase, a kinetic mechanism proposed and the catalytic properties of the enzyme described. It is important, however, to determine the kinetic parameters of the reaction catalyzed by whole cells, if the process is to be designed with the catalyst in this form.