Clostridium perfringens Vitality as an Ecotoxicity Test for Measuring the Lead Concentration in Sediment

摘要

Lead is a priority substance of the Water Framework Directive and for thisreason the emissions, releases, and losses should be reduced within a certain deadline.Native lead occurs in nature very rarely and currently lead can be found bounded to zinc,silver, and copper. On the other hand, particles of lead that are emitted to air by humanactivities can remain in atmosphere for several weeks and travel long distances dependanton particle size. Due to these activities, lead is so common in the environment that it canreach man via air, food, water, dust, or soil. Deposition from atmosphere is a major contributorto lead inputs to water and land. After deposition in water, depending on saltcontent of the water and the presence of organic complexing agents, lead splits betweenwater and sediment. In order to contribute to the knowledge of these mechanisms, thisstudy aimed at detecting the effect of lead on the vitality of Clostridium perfringenspopulation in a determined, experimentally controlled sediment matrix using a luminescentreaction. Here we use pure culture of microorganisms to evaluate specific risks oflead polluted sediments. C. perfringens is a spore forming anaerobic rod that does notcarry out a dissimilatory reduction of sulphate, therefore, can be used as indicator forfaecal pollution. Artificially polluted sediment was contaminated with a pure culture ofC. perfringens. Bacterial vitality was measured for a period of 40 hours by luminescencemethod using the BacTiterGlo?-assay, both in the blank sediment and in the sedimentsadded with 50 ppm, 250 ppm and 760 ppm lead concentrations. The results of the performedecotoxicity test using the BacTiterGlo?-assay showed a significant decrease inbacterial vitality at 760 ppm concentration. This effect occurs within the first 16 hoursand, therefore, the initial experimental time adopted in the protocol can be reduced to thisrange of time. The results showed that lead concentrations that influence C. perfringensvitality are similar to those found in hazardous waste sites. Next steps, the effect of leadshould be observed in this range of concentration and within this period of time withmore replicates and shorter time distances between the measurements. In addition, theecotoxicological effect observed in this way, should be tested also in different types ofsediments and with different environmental strains to determine sensitivities throughcombination of sediment properties and properties of microorganisms.