Photodynamic Antimicrobial Chemotherapy in Aquaculture: Photoinactivation Studies of Vibrio fischeri

BACKGROUND: Photodynamic antimicrobial chemotherapy (PACT) combines light, a light-absorbing molecule that initiates a photochemical or photophysical reaction, and oxygen. The combined action of these three components originates reactive oxygen species that lead to microorganisms' destruction. The aim was to evaluate the efficiency of PACT on Vibrio fischeri: 1) with buffer solution, varying temperature, pH, salinity and oxygen concentration values; 2) with aquaculture water, to reproduce photoinactivation (PI) conditions in situ. METHODOLOGY/PRINCIPAL FINDINGS: To monitor the PI kinetics, the bioluminescence of V. fischeri was measured during the experiments. A tricationic meso-substituted porphyrin (Tri-Py(+)-Me-PF) was used as photosensitizer (5 µM in the studies with buffer solution and 10-50 µM in the studies with aquaculture water); artificial white light (4 mW cm(-2)) and solar irradiation (40 mW cm(-2)) were used as light sources; and the bacterial concentration used for all experiments was ≈10(7) CFU mL(-1) (corresponding to a bioluminescence level of 10(5) relative light units--RLU). The variations in pH (6.5-8.5), temperature (10-25°C), salinity (20-40 g L(-1)) and oxygen concentration did not significantly affect the PI of V. fischeri, once in all tested conditions the bioluminescent signal decreased to the detection limit of the method (≈7 log reduction). The assays using aquaculture water showed that the efficiency of the process is affected by the suspended matter. Total PI of V. fischeri in aquaculture water was achieved under solar light in the presence of 20 µM of Tri-Py(+)-Me-PF. CONCLUSIONS/SIGNIFICANCE: If PACT is to be used in environmental applications, the matrix containing target microbial communities should be previously characterized in order to establish an efficient protocol having into account the photosensitizer concentration, the light source and the total light dose delivered. The possibility of using solar light in PACT to treat aquaculture water makes this technology cost-effective and attractive

Saúde e ambiente no Brasil: desenvolvimento, território e iniqüidade social Health and environment in Brazil: development, territory, and social iniquity

As autoras apresentam uma abordagem das iniqüidades sócio-ambientais no Brasil, decorrentes do modelo de desenvolvimento, no contexto atual da globalização, e as perspectivas da luta social. A realização histórica da ideologia do desenvolvimento tem implicado em profundas transformações do território, com sérias repercussões sobre a saúde das populações e dos ecossistemas, as quais apenas muito recentemente começam a ser reconhecidas como problemas na agenda social. A tentativa de conciliar soluções para a crise social e a crise ambiental resultou na formulação da proposta de desenvolvimento sustentável - incorporada em alguns novos discursos no campo da saúde coletiva - cuja análise crítica é o ponto de partida deste artigo. O território foi examinado como um operador útil para analisar a expressão da ligação entre saúde, ambiente e desenvolvimento, revelador do paradoxo entre as potencialidades naturais e humanas do Brasil e sua pobreza, espelho da injustiça ambiental e da violação de direitos humanos. Trata-se de um conceito expandido de ordenação territorial, importante para criar a possibilidade de se compreender o contexto de modernização e de possibilidade das populações pobres conquistarem uma vida melhor.<br>The present paper deals with the subject of socio-environmental injustice in Brazil as a consequence of the country's current development model in the context of globalization and from the perspective of social struggle. Over time the realization of the development ideology has introduced profound changes in the country's territory, with severe repercussions for population and ecosystem health that have only recently been included on the social agenda. Efforts to reconcile solutions to the social and environmental crises have converged in the concept of sustainable development, within new discourses in the field of collective health (and whose analysis provides the point of departure for this paper). Territory is explored as a useful tool for analyzing the relationship between health, environment, and development, revealing the paradox between Brazil's great natural and human potential and its poverty, reflecting environmental injustice and disregard for human rights. This expanded concept of territorial organization is important for understanding the context of modernization and the possibility for poor populations to enjoy a better life