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The purpose of this study was to discuss the effect of the chemical structure of anionic and non-ionic surfactants and surface activity on toxicity. Single and binary mixtures of three ether carboxylic derivative sur- factants and three amine-oxide-based non-ionic surfactants were used. Toxicity was determined using three test organisms: freshwater crustaceans (Daphnia magna), luminescent bacteria (Vibrio fischeri), and microalgae (Selenastrum capricornutum). The toxicity of surfactants is related to the hydrophobic alkyl chain, the degree of eth- oxylation, and the critical micelle concentration of sur- factants. Relationships found agreed with the fact that the lower toxicity is shown by the shorter alkyl chain. There is a strong relation between surface activity and toxicity: the toxicity increased as the CMC of the surfactant or mixtures of surfactants decreased. Commercial products are formu- lated using surfactants mixtures, so it is important to know their behavior using an easily measured property: the least toxic mixtures were formed by the surfactants having lower individual toxicity. Around the CMC, our data show a synergism for the binary mixtures. The results have given rise to a classification of the different surfactants and their mixtures according to the organism test, as safe, harmful or toxic. V. fischeri was in general the most sensitive micro- organism to the toxic effect of the surfactants, followed by Daphnia magna, while Selenastrum capricornutum was more tolerant. These results can be useful for selecting technically efficient surfactants and their mixtures with a lower ecotoxicity on the aquatic environment.

Bioluminescence is emitted by various living organisms, including bacteria. While the induction mechanism in marine luminescent bacteria, such as Vibrio fischeri and V. harveyi, has been well characterized, this mechanism has not been studied in detail in the non-marine luminescent bacterium Photorhabdus luminescens. Therefore, we investigated the effect of cations and anions on the induction of luminescence by P. luminescens. Cultivation of cells in an inorganic salts solution (ISS) containing KCl, CaCl2, MgCl2, NaHCO3, and MgSO4 resulted in a rapid increase in luminescence intensity. Moreover, the induction of luminescence in the ISS medium was not dependent on cell density, since cell densities remained unchanged during 48 h. Furthermore, we found that compounds containing K+, Mg2+, and HCO3– were necessary to induce cell density-independent luminescence. The intensity of luminescence per cell cultured in medium containing KCl, MgCl2, and NaHCO3 was approximately 100-fold higher than that cultured in NB. In contrast, when cells actively grew in normal growth condition, the intensity of luminescence per cell was not increased even in the presence of K+, Mg2+, and HCO3–. Thus, these results suggest that the luminescence of P. luminescens is regulated by 2 independent cell density-dependent and -independent mechanisms.

Luminescent bacteria and nematodes associate in a strategy where the bacteria act as virulent pathogens of insects, used as their food supply, while the nematodes graze on them. Upon reaching high density, the bacteria produce light and metabolites that turn the nematodes into hosts permitting them to be carried over to further nematode preys. In this issue of Molecular Microbiology, Lango and Clarke show that the corresponding shift in lifestyle is triggered by a metabolic switch closely linked to the tricarboxylic acid cycle, but apparently not by the well-known acetate switch that monitors entry of bacteria into the stationary phase of growth.

The toxicity of sediments in the Gulf of Gdansk is analyzed in relation to the chemical composition of interstitial and near-bottom waters, and sediment properties. The toxicity of sediments, pore waters and saline elutriates is determined by using the Microtox ® test based on changes in light production of the luminescent bacteria Vibrio fischeri. The results indicate considerable toxicity in the majority of examined sediments. Since the sediment elutriates and pore waters are toxic in some cases, the total toxicity of the sediments is likely to be due to both sediment-bound and water soluble substances. The sediment toxicity is related to the percentage contribution of the fine fraction of sediments. A significant correlation between the toxicity of the sediments and the black carbon content implies anthropogenic contamination. The toxicity of the sediments is seen to increase with the increase of hydrogen sulfide concentration in pore waters. The ammonia in pore waters was found not to be responsible for the toxicity of the sediments.

Luminescent bacteria in the family Vibrionaceae (Bacteria: c-Proteobacteria) are commonly found in complex, bilobed light organs of sepiolid and loliginid squids. Although morphology of these organs in both families of squid is similar, the species of bacteria that inhabit each host has yet to be verified. We utilized sequences of 16S ribosomal RNA, luciferase a-subunit (luxA) and the glyceraldehyde-3-phosphate dehydrogenase (gapA) genes to determine phylogenetic relationships between 63 strains of Vibrio bacteria, which included representatives from different environments as well as unidentified luminescent isolates from loliginid and sepiolid squid from Thailand. A combined phylogenetic analysis was used including biochemical data such as carbon use, growth and luminescence. Results demonstrated that certain symbiotic Thai isolates found in the same geographic area were included in a clade containing bacterial species phenotypically suitable to colonize light organs. Moreover, multiple strains isolated from a single squid host were identified as more than one bacteria species in our phylogeny. This research presents evidence of species of luminescent bacteria that have not been previously described as symbiotic strains colonizing light organs of Indo-West Pacific loliginid and sepiolid squids, and supports the hypothesis of a non-species-specific association between certain sepiolid and loliginid squids and marine luminescent bacteria. � The Willi Hennig Society 2007.

This study evaluated the toxic effects of substituted anilines on Pseudokirchneriella subcapitata with the use of a closed algal toxicity testing technique with no headspace. Two response endpoints (i.e., dissolved oxygen production [DO] and algal growth rate) were used to evaluate the toxicity of anilines. Both DO and growth rate endpoints revealed similar sensitivity to the effects of anilines. However, trichloroanilines showed stronger inhibitory effects on microalgal photosynthetic reactions than that on algal growth. For various aquatic organisms, the relative sensitivity relationship for anilines is Daphnia magna > luminescent bacteria (Microtox) > or = Pocelia reticulata > or = Pseudokirchneriella subcapitata > or = fathead minnow > Tetrahymena pyriformis. The susceptibility of P. subcapitata to anilines is similar to fish, but P. subcapitata is apparently less sensitive than the water flea. The lack of correlation between the toxicity revealed by different aquatic organisms (microalgae, D. magna, luminescent bacteria, and P. reticulata) suggests that anilines might have different metabolic routes in these organisms. Both hydrogen bonding donor capacity (the lowest unoccupied molecular orbital energy, Elumo) and hydrophobicity (1-octanol:water partition coefficient, Kow) were found to provide satisfactory descriptions for the toxicity of polar narcotics (substituted anilines and chlorophenols). Quantitative structure-activity relationships (QSARs) based on Elumo, log Kow, or both values were established with r2 values varying from 0.75 to 0.92. The predictive power for the QSAR models were found to be satisfactory through leave-one-out cross-validation. Such relationships could provide useful information for the estimation of toxicity for other polar narcotic compounds.

The toxicities of cyanide and tetramethylene disulfotetramine (tetramine) were evaluated by two methods of luminescent bacteria and PbO2 electrochemical sensor. Vibrio-qinghaiensis, a kind of luminescent bacteria, can produce bioluminescence and the bioluminescence was decreased with the addition of toxicants. The toxicities of cyanide and tetramine were expressed as 10 min-EC50 value, which was the concentration of chemical that reduces the light output by 50% after contact for 10 min. Nano PbO2 modified electrode, a rapid toxicity determination method was also described in this work. By the PbO2 modified electrode, the current responses of Escherichia coli (E. coli) were changed with the addition of toxicants. The value of 10 min-EC50 was also provided with the PbO2 electrochemical sensor. Compared with the 10 min-EC50 and detection limits (38.38 and 0.60 µg/mL for cyanide, 0.24 and 0.02 µg/mL for tetramine) with luminescent bacteria, the PbO2 sensor provided a simple and convenient method with lower 10 min-EC50 and detection limits (26.37 and 0.52 µg/mL for cyanide, 0.21 and 0.01 µg/mL for tetramine) and fast response time.

In this paper, it was found that luminescent bacteria could be killed by UV light and the bioluminescence intensity would be decreased. With the protection of nanooxide, the decrease of the bioluminescence could be supressed, therefore luminescent bacteria could be utilized to analyze and evaluate the UV-shielding property of nanooxide. Vibrio-qinghaiensis Q67, a kind of luminescent bacteria, was used here to study the influence of different kinds and concentrations of nanooxide on the luminescence intensity of bacteria, which were illuminated by UVA, UVB or UVC light, respectively. A method was established according to the relative value of the decrease of the luminescence intensity, which can be used to analyze and evaluate the UV-shielding property of nanooxide against UVA, UVB or UVC light, respectively. It also provided an effective way to analyze and evaluate the UV-shielding property of sunscreen for cosmetic and other industries.

Various approaches and technologies that utilize luminescent bacteria for determination of water quality are described. The use of intact luminescent bacteria for analytical purposes has some clear advantages: the light of a single bacterium may reach about 30,000 quanta/s/cell; thus, one can use a simple luminometer to detect light generated by a few hundred cells/mL. Chemophysical and biological factors that affect cell respiration, the rate of protein or lipid synthesis, promptly alter the level of luminescence. The use of freeze-dried luminescent bacteria for analytical purposes is not different, in practice, from other biochemical tests. Numerous studies described the use of natural luminescent bacteria or recombinant lux-carrying bacteria for rapid assessment of toxic components in aqueous environments. The commercially available bioassays are described in detail (Microtox, ToxScreen, Mutatox, Vitotox), as well as recent developments in automating toxicity tests for online monitoring. Also described are tests utilizing luminescent bacteria for determination of nutrients in water [such as assimilable organic carbon (AOC) and biochemical oxygen demand (BOD)]. All in all, the bioluminescence tests for detecting water toxicants as well as for measuring elementary nutrients have been shown to be simple, rapid, and relatively inexpensive tools for monitoring water quality. Keywords: assimilated organic carbon; automatic toxicity monitoring; biochemical oxygen demand; luminescent bacteria; microtox; mutatox; toxscreen; toxicity testing; short-term bioassays; water quality

At the EILATox-Oregon Workshop, nine luminescent whole-cell bacterial sensors were used for the determination of bioavailable metals in blind samples (17 synthetic and 3 environmental). A non-inducible luminescent control strain was used to determine sample matrix effects and bacterial toxicity. Whole-cell bacterial sensors capable of determining arsenic, inorganic mercury and its organic derivatives, cadmium, lead or copper were used in suspensions and a bacterial sensor for the detection of inorganic mercury was immobilized onto fibre-optic tips using calcium alginate. Bioavailable amounts of metals were estimated using calibration plots, that were constructed to determine the range of metals giving rise to a linear relationship between luminescence and the amount of metals present in the standard solutions. EILATox-Oregon sample 5, which contained 74 mg l−1 of Hg, gave a significant response with both formats of the mercury sensor. The bioavailable amounts of mercury according to the measurement of bacterial sensor in suspension and immobilized onto a fibre-optic tip were 76 and 93 mg l−1, respectively. The bacterial sensor for arsenic and copper showed a response with sample 6 (58 mg l−1 of As) and sample 8 (400 mg l−1 of metham sodium), respectively. This study showed that the bacterial sensors in suspension or immobilized onto optical fibres are capable of quantifying bioavailable metals from unknown samples. The measurement protocol of bacterial sensors is simple and possible to perform in the field. Moreover, the samples do not need any pretreatment before analysis. Construction and characterization of the strain for the detection of bioavailable copper are described. Copyright © 2004 John Wiley & Sons, Ltd.

Light-emitting bacteria are the most abundant and widespread luminescent organisms. Most species of such bacteria live in marine environments. However, until recently, biological role of bacterial luminescence remained unknown. Recent studies indicated that light produced in bacterial cells may stimulate DNA repair. Therefore, it is not surprising that agents that cause DNA damage induce expression of lux genes. Moreover, it was proposed previously that bacterial luciferases may be involved in detoxification of reactive oxygen species. Recently, this hypothesis was confirmed experimentally. Here we investigated effects of hydrogen peroxide on light emission by various strains of luminescent bacteria. We found that luminescence of strains with luciferase of fast kinetics of reaction decreased at considerably lower concentrations of H2O2 than that of strains with luciferase of the slow kinetics. The action (either direct or indirect) of luciferases as anti-oxidants seemed to be independent of activity of catalase, which was found to be different in various strains. Therefore, it seems that luciferases of the slow kinetics are more efficient in detoxification of reactive oxygen species than those of the fast kinetics. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

An acute toxicity model was constructed on the basis of 901 chemicals tested for toxicity against the luminescent bacteria Vibrio fischeri (formerly Photobacterium phosphoreum, the Microtox® test). The model was created using the Multiple Computer-Automated Structure Evaluation (M-CASE) program. The model can correctly predict acute toxicity for 92% of the compounds with an error averaging 0.55 log units per median effect concentration (EC50). The main toxicophores, corresponding to polar and nonpolar narcosis, and other types of reactive chemicals were identified.

It was demonstrated recently that luminescence of a free-living marine bacterium, Vibrio harveyi, stimulates DNA repair, most probably by activation of the photoreactivation process. Here, we ask whether the stimulation of DNA repair could be an evolutionary drive that ensured maintenance and development of early bacterial luminescent systems. To test this hypothesis, we cultivated V. harveyi lux+ bacteria and luxA mutants in mixed cultures. Initial cultures were mixed to obtain a culture consisting of roughly 50% lux+ cells and 50% luxA mutants. Then bacteria were cultivated for several days and ratio of luminescent to dark bacteria was measured. Under these conditions, luxA mutants became highly predominant within a few days of cultivation. This indicates that, without a selective pressure, the luminescence is a disadvantage for bacteria, perhaps due to consumption of significant portion of cell energy. However, when the same experiments were repeated but cultures were irradiated with low UV doses, luminescent bacteria started to predominate shortly after the irradiation. Therefore, we conclude that stimulation of photoreactivation may be an evolutionary drive for bacterial bioluminescence. Copyright © 2003 John Wiley & Sons, Ltd.

Sunlight can greatly enhance the toxicity of polycyclic aromatic hydrocarbons (PAHs). Photosensitization reactions (e.g., generation of singlet-state oxygen) and photomodification reactions (e.g., photooxidation of PAHs to more toxic species) are both pathways of photoinduced toxicity of PAHs. Previously, a quantitative structure-activity relationship (QSAR) was developed for PAHs showing that a photosensitization factor (PSF) and photomodification factor (PMF) can be additively combined to describe photoinduced toxicity. That QSAR model was developed for the photoinduced toxicity of 16 PAHs to the higher plant Lemna gibba. The objective of this study was to apply the QSAR model developed for L. gibba to another organism. The organism chosen was the luminescent marine bacteria Vibrio fischeri. Toxicity data used for the QSAR model were inhibition of luminescence and inhibition of growth of V. fischeri. Both short-term (15 min) and long-term (18 h) assays of toxicity were used. Light did not impact on PAH toxicity in the short-term assay, and thus the QSAR model did not correlate well with these data. Conversely, light greatly enhanced toxicity when the long-term assay was employed. The PMFs for the PAHs from the L. gibba QSAR showed a moderate correlation to bacterial toxicity in the long-term assay, whereas the PSFs showed only a weak correlation to toxicity. As was the case for L. gibba, summing the PMF and the PSF resulted in a strong correlation to toxicity that had predictive value. Thus, a QSAR model derived for plants accurately described the toxicity of PAHs to a bacterial species. This indicates that the bipartite mechanism of PAH-photoinduced toxicity may be applicable to other organisms.

The fumigant 1,3-dichloropropene (1,3-D) is one of the most heavily used pesticides but also a suspected carcinogen. Previous research has shown that 1,3-D was rapidly transformed and detoxified by ammonium thiosulfate (ATS), a sulfur and nitrogen fertilizer. As common formulations contain cis and trans isomers at roughly equivalent ratios, this study was conducted to understand isomeric differences in thiosulfate transformation and detoxification of 1,3-D. Under the same conditions, reaction of cis-1,3-D with thiosulfate was more than three times faster than trans-1,3-D, which was correlated with a lower reaction activation energy for the cis isomer. The trans isomer was considerably more toxic to the luminescent bacteria Vibrio fisheri than the cis isomer, but the toxicity was reduced by 14 times after thiosulfate transformation. Mutagenic activity to strains of Salmonella typhimurium was observed for trans-1,3-D but was not detected after thiosulfate transformation. These results suggest that thiosulfate transformation detoxifies 1,3-D primarily by deactivating the trans isomer, and the reaction is toxicologically beneficial, as it negates the potential harmful effects of 1,3-D to the environment and human health.

This paper presents the statistical analysis of the results of an inter-laboratory study for the luminescent bacteria toxicity bioassay. It also contains a discussion on the statistical methods for the presentation and refinement of the evaluation of the precision of an assay method (including intra- and inter-laboratory variability), with special emphasis on the rejection of outliers, and the use of standardized parameters, like the repeatability and reproducibility values.

The production of light in most luminescent bacteria lags behind cellular growth with induction of luminescence only occurring at high cell density. The maximum intensity and the cell density reached before induction of luminescence is highly dependent on the bacterial species and the growth conditions including temperature, salt and nutrient composition as well as other experimental conditions. Although common N-acylhomoserine lactone autoinducers have been identified in Vibrio (Photobacterium) fischeri and Vibrio harveyi, most regulatory components are quite different. Recognition of the common as well as the different elements controlling luminescence in the diverse bacterial species is essential to understand the basis for high levels of light emission at the later stages of cellular growth. Copyright © 1999 John Wiley & Sons, Ltd.

In conjunction with aquatic bioassays, the effect of microplate (MP) material on the sensitivity of a cell multiplication inhibition test with luminescent bacteria (as representatives for unicellular organisms) was examined. The tested substances were four organic chemicals of different hydrophobic properties (4-nitrotoluene, 3,5-dichlorophenol, 2-chloroaniline, sodium phenolate) and waste water from a chemical production plant. The study revealed, that (except for sodium phenolate) the toxic response to the testing material was influenced by the MP material. The employment of the common plastic MP led to an underestimation of the biotests results. Therefore it must be taken into consideration, that when using the microplate technique to expose unicellular organisms to toxic chemicals with hydrophobic properties, only MP made of quartz glass should be employed. ©1999 John Wiley & Sons, Inc. Environ Toxicol 14: 424–428, 1999

Elemental sulfur occurs naturally in marine and limnic sediments. Elemental sulfur, brought in solution in aqueous media by using organic solvents such as methanol as carrier solvent, was toxic in a bacterial luminescence test, known as the Microtox test. Previously, it has been shown that the toxicity in the luminescence test of whole sediments also was correlated to i.a. elemental sulfur using multivariate statistical analysis. Organic solvent extracts of sediments obtained in receiving waters of effluents from a pulp and paper mill was toxic in the luminescence test, and using a toxicity evaluation procedure, the toxic substance was identified as octameric cyclic sulfur, S8. The substance dominated the toxicity in extracts of both a contaminated sediment and a sediment from a control area. Since the toxicity in the Microtox test of aqueous solutions of S8 decreased upon storage, a conversion process of the toxic form was indicated. Acute toxicity of S8 was not limited to the luminescent bacteria in the Microtox test, but was observed in tests with fish larvae if tested with the transient form of elemental sulfur. Tests of acute toxicity with zebra fish and perch larvae were responsive to elemental sulfur. Probably, the toxic form of elemental sulfur is the single cyclic octamer, that due to low aqueous solubility, binding to particulate sediment material or aggregation is converted into a nontoxic form. Acute toxic effects may occur in sulfur containing sediments of varying redox potentials or where elemental sulfur deposits are turbated. © 1998 John Wiley & Sons, Inc. Environ Toxicol Water Qual 13: 217–224, 1998

A simplified fingerprint, obtained by counting the colonies of luminescent and nonluminescent bacteria developing on filters plated on a solid culture medium, was applied to obtain an indication of coastal water quality. Results from a reference area and three polluted sites (essentially by urban sewage) and their variations during the year are reported. A tentative characterization of the “clean” and polluted sites is made.

Abwasser aus Textilveredlungsbetrieben wurden mit Hilfe von Biotestverfahren untersucht. Es wurden Fisch-, Daphnien-, Leuchtbakterien-, Hamsterzell-, Ames- und Zahn-Wellens-Tests durchgefuhrt. Grundlage ist die Rahmenabwasser-Verwaltungsvorschrift, basierend auf § 7a WHG, in deren Anlage bereits mehrere Biotestverfahren aufgenommen wurden. Die Toxizitat der Textilabwasser ist im Vergleich zu anderen Industrieabwassern nur in Einzelfallen herausragend. Jedoch ist eine grose Anzahl der Proben (27%) der Indirekteinleiter im nativen Zustand mutagen im Ames-Test. In Folgetests auf Chromosomenaberrationen (V79-Hamsterzelltest) zeigten daruber hinaus 5 von 9 nativen Proben ein mutagenes Potential. Die Empfindlichkeit der okotoxikologischen Untersuchungsmethoden wird diskutiert. Die mutagenen Effekte werden auch mit der Untersuchung von Altstoffen und dem Chemikaliengesetz in Verbindung gebracht. Testing Effluents of the Textile Refining Industry with Biological Methods The environmental problems caused by the manufacture of finished textiles involve a long chain of individual processes. This “textile chain” includes very diverse enterprises of varied size and structure. The textile refiners occupy a key position in the “textile chain”. On the one hand, this is due to their use of an obscurely large number of chemicals which can end up in the wastewater as well as in the textile products. On the other hand, this key role of the textile refining industry is based on their central position between the preproduction stage and the consumers. This study dealt with the textile refining industry's wastewater. As measured by volume and contents of its wastewater, this industry can be counted among the major industrial plants which discharge into municipal wastewater treatment plants. German wastewater legislation includes the provision that substances which are toxic, persistent, capable of accumulating, carcinogenic, fetotoxic or mutagenic be kept out of natural waters as well as technically possible (Wasserhaushaltsgesetz WHG). Several biotest methods for examining the effect of the substances contained in the wastewater were incorporated into the appendix of the German wastewater regulation (Rahmenabwasser-Verwaltungsvorschrift based on § 7a WHG). The aim of this study was to show, with the aid of biotest methods, how strongly the wastewater of textile refining companies is polluted as compared to other known industrial branches and to what degree the pollution of these wastewaters is eliminated by the treatment in wastewater treatment plants. Finally, we experimented to find out which biotest methods were suited for the examination of these wastewaters. The study's results show that the ecotoxicity of the textile refining industry's wastewater was only extraordinary high in isolated cases as compared to other examined branches of industry. The textile wastewaters exhibit values of GL = 3 to GL = 96 in the luminescent bacteria test, GD = 1 to GD = 192 (with one exception of GD > 30000) in the daphnia test and GF < = 2 to GF = 32 in the fish test. It turned out though, that a large number of the samples from the textile refining companies (27%) reacted mutagenically in the Ames test in their native state. Consecutive tests for chromosomal aberrations (V79 hamster cell test) also showed mutagenic potential in five out of nine native samples. The employed testing methods with fish, daphnia and luminescent bacteria demonstrate a higher sensitivity of the luminescent bacteria and/or the daphnia as opposed to the fish in most cases. As the fish test is controversial anyway on the grounds of animal protection, a replacement of the fish test by these other tests should be aimed at: on account of the different end points of the luminescent bacteria and the daphnia test, a combination of these tests appears most sensible.

Among several bioassays, the Scenedesmus subspicatus chlorophyll fluorescence test and the Photobacterium phosphoreum bioluminescence assay were selected to examine their applicability for toxicity evaluation of changes in coke plant effluent quality. In addition to the ecotoxicological parameters, a chemical analysis of dissolved organic carbon (DOC), ammonia-N, and nitrate-N was performed. It was demonstrated that the toxicity values obtained from the bioassays give a first indication on potential hazard and successful treatment. Decreasing toxicity values went along with decreasing DOC or ammonia-N values, but the sensitivity toward DOC reduction was higher. Sensitivity toward pure compounds was assessed by comparing the EC50 values of the luminescent bacteria assay with the corresponding EC50 values of the algal bioassay. The data showed a poor correlation between the two bioassays. © by John Wiley & Sons, Inc.

The bacterial bioluminescence assay is widely used to estimate chemical cytotoxicity. This assay is performed most often by using luminescent bacteria Vibrio fisheri NRRL-B-11177 (earlier cited as Photobacterium phosphoreum NRRL-B-11177) as a test organism. In this work we have used cloned gram(+) and gram(-) bacterial strains for the evaluation of chemical toxicity. Two types of luciferase genes were used as reporter genes, one of which was ATP-dependent eukaryotic luciferase from Pyrophorus plagiophthalamus and the other was FMN-dependent bacterial luciferase from Vibrio harveyi. These cloned strains were used to evaluate the effects of differences in cell wall structures in the bioluminescence cytotoxicity test using small molecular weight toxic chemicals as model compounds. The strains were found to have remarkably similar behavior and sensitivity toward test toxicants regardless of rather different kinds of membrane structure. However, the eukaryotic luciferase was found in every aspect more useful in toxicity tests than bacterial luciferase mainly because of increased sensitivity and ease of operation. The general behavior of the light emission is described and several aspects affecting the usefulness of the strains are discussed. © by John Wiley & Sons, Inc.

The toxic effect of single organic contaminants to aquatic biota is relatively easy to assess using classic aquatic toxicity bioassays. Unfortunately, contaminants are present in the aquatic environment in mixtures of unknown composition. Moreover, antagonistic and synergistic interactions make the prediction of the real environmental hazard posed by organic contaminants more complicated. A mathematical algorithm has been developed to predict the toxicity of mixtures of organic contaminants to aquatic biota using toxicity data for the individual components of the mixture. The Microtox® toxicity bioassay was used to obtain the toxicity data for a set of chlorinated phenols that were used as test compounds to validate the model. The unique characteristics of the Microtox bioassay make it a perfect tool to confirm experimentally the ability of the model to estimate the combined toxic effect of mixtures of organic contaminants.

The effects of hydrogen sulfide (H2S) were tested in three ecotoxicological tests in order to evaluate its confounding potential in assessment of pore water and groundwater toxicity. The luminescent bacteria Vibrio fischeri, the water flea Daphnia magna, and the microalgae Scenedesmus vacuolatus often are part of a biotest battery. A new technique for the synthesis of hydrogen sulfide solutions of defined concentrations using an electrochemical generator instead of sodium sulfide solutions was used. Because hydrogen sulfide is volatile, the loss rate of H2S was studied over time to enable estimation of the mean test concentrations over the whole test duration. Loss rates were calculated to be 13 +/- 6% after 30 min, and 39 +/- 11% and 43 +/- 16% after a 24- and 48-h exposure time, respectively. Sensitivities of the test organisms in terms of median effective concentration (EC50), corrected for the above loss rates, varied from 0.28 to 0.0036 and 0.055 mM for the luminescent bacteria, the crustacea, and the algae, respectively. A species-sensitivity distribution using EC and mean lethal concentration literature data for marine and freshwater crustaceans and phytoplankton showed a medium sensitivity of the water flea D. magna, though the bacteria V. fischeri and the algae S. vacuolatus were among the least-sensitive group of organisms. This demonstrates that only the algae and the bacteria are easy to use in the assessment of toxicity of matrices with H2S concentrations above 0.06 mM.

Hazard assessment of industrial sites contaminated with coal tar and its products usually focuses on selected pollutants such as the 16 polycyclic aromatic hydrocarbons (PAHs) prioritized by the U.S. Environmental Protection Agency (U.S. EPA). The aim of this study was to investigate to which extent these 16 PAHs contribute to the Vibrio fischeri bioluminescence inhibition measured by the acute Lumistox® luminescent bacteria test. Five of the 16 PAHs-naphthalene (NAP), acenaphthylene (ACY), acenaphthene (ACE), fluorene (FLU), and phenanthrene (PHE)-revealed inhibiting effects when measuring saturated aqueous solutions of these compounds. However, in elutriates of PAH-contaminated soils, the amount of leached PAHs was very low, and the 16 PAHs did not considerably contribute to the observed bioluminescence inhibition. Nevertheless, bioluminescence inhibition was higher for elutriates with increased PAH concentration indicating the presence of other toxicants that co-occur with the 16 PAHs. No evidence was observed for increased bioluminescence inhibition due to synergistic effects among PAHs as calculated on the basis of toxic units for an aqueous solution containing all 16 priority PAHs. Data suggest that the U.S. EPA PAHs play only a minor role in causing acute toxicity to V. fischeri when exposed to aqueous elutriates of PAH-contaminated soils.

Dispersants are a preapproved chemical response agent for oil spills off portions of the U.S. coastline, including the Texas-Louisiana coast. However, questions persist regarding potential environmental risks of dispersant applications in nearshore regions (within three nautical miles of the shoreline) that support dense populations of marine organisms and are prone to spills resulting from human activities. To address these questions, a study was conducted to evaluate the relative toxicity of test media prepared with dispersant, weathered crude oil, and weathered crude oil plus dispersant. Two fish species, Cyprinodon variegatus and Menidia beryllina, and one shrimp species, Americamysis bahia (formerly Mysidopsis bahia), were used to evaluate the relative toxicity of the different media under declining and continuous exposure regimes. Microbial toxicity was evaluated using the luminescent bacteria Vibrio fisheri. The data suggested that oil media prepared with a chemical dispersant was equal to or less toxic than the oil-only test medium. Data also indicated that continuous exposures to the test media were generally more toxic than declining exposures. The toxicity of unweathered crude oil with and without dispersant was also evaluated using Menidia beryllina under declining exposure conditions. Unweathered oil-only media were dominated by soluble hydrocarbon fractions and found to be more toxic than weathered oil-only media in which colloidal oil fractions dominated. Total concentrations of petroleum hydrocarbons in oil-plus-dispersant media prepared with weathered and unweathered crude oil were both dominated by colloidal oil and showed no significant difference in toxicity. Analysis of the toxicity data suggests that the observed toxicity was a function of the soluble crude oil components and not the colloidal oil.

Toxicity studies are generally conducted with single chemicals under standardized conditions. Yet results with the same substances can be different if antagonistic or synergistic interactions occur with the test medium constituents. In fact the toxic response of various chemicals seems highly dependent on temperature, contact time, salinity, buffering substances and water hardness. As Microtox test has previously been used to assess the toxicity of pure chemicals and complex effuents, it is interesting to study how some physico-chemical interactions can modulate the response of the luminescent bacteria in this system. In the present investigation, the effects of the test temperature and the role of pH, buffers, hardness and salinity were studied for different times of exposure of the Microtox bacterial reagent to various inorganic and organic compounds including cadmium, zinc, pentachlorophenol and benzene. The results indicated that physicochemical parameters must be considered when analyzing Microtox data of complex effuents or mixtures of chemicals.

The toxicity assessment of chemicals on complex microbial communities are generally preferred to toxic tests conducted with pure cultures of bacteria. The purpose of this study is to compare the “Respiration” test studying metabolic criteria of mix bacterial populations and the “Microtox” test using lyophilized cultures of luminescent bacteria. The inhibition of oxygen consumption was compared with the inhibition of the bioluminescence of Photobacterium phosphoreum. In the first part of this study, the methodology of the “Respiration” test and the “Microtox” test was improved to optimize their performance in toxicity assessment. In the second part, toxicity of an organic chemical, the 3,5-Dichlorophenol, and an inorganic chemical, copper sulfate, was evaluated with the two tests. Results were compared and characteristics of the testing methods are discussed according to their sensitivity, reproducibility, representativity and ease of execution. The repeatability study for the “Respiration” test and the “Microtox” test gives variation coefficients less than 15% and 10% respectively. The variation coefficients concerning the reproducibility study are found to be 15% or 18% for the “Respiration” test, 5% or 28% for the “Microtox” test, depending on the tested toxicant. These two toxicity tests are easy to perform. But the “Microtox” test offers the advantage of being more sensitive and much faster. On the other hand, the “Respiration” test which was conducted on a microbial community is probably more representative of microflora in rivers.

Data on the action of mono- and polyatomic phenol mixtures on hydrobionts are discussed. Luminescent bacteria, Daphnia, algae zoospores, higher aquatic plants–Elodea and duckweed – were used as test objects. It is established that the toxicity of a paired mixture of mono- and polyatomic phenols is lower than the toxicity of their components.

In this study bacterial luminescent toxicity tests (LTT) were used to monitor the residual toxicity concentration of a biocide-inhibitor after several months storage. The study was completed in two parts. The first study investigated the relationship between the chemical and toxicity concentrations of a biocide-inhibitor stored in mild steel containers and glass containers. After three months storage in the mild steel containers there was a significant difference (p < 0.01) between the chemically assayed level of the biocide-inhibitor and the toxicity level determined by the LTT. The results of the laboratory studies were confirmed in the second part of the study when the biocide-inhibitor was incorporated in the sea water used to flood a large undersea pipeline during the pressure testing programme. The disparity between the chemical and toxic assayed concentrations was not as great when the biocide-inhibitor was stored in glass containers. The influence of the container used for biocide testing plus the failure of the chemical analysis to reflect the toxicity level of this biocide-inhibitor demonstrates a different application of LTT. The results of this study also illustrate the usefulness and relevance of LTT in testing the effectiveness of some biocides and indicate that LTT could be useful in monitoring the efficiency of biocides during their industrial application.