Cultivation of Sponge Larvae: Settlement,Survival, and Growth of Juveniles

The aim of this study was to culture sponge juveniles from larvae. Starting from larvae we expected to enhance the survival and growth, and to decrease the variation in these parameters during the sponge cultures. First, settlement success, morphological changes during metamorphosis, and survival of Dysidea avara, Ircinia oros, Hippospongia communis, under the same culture conditions, were compared. In a second step, we tested the effects of flow and food on survival and growth of juveniles from Dysidea avara and Crambe crambe. Finally, in a third experiment, we monitored survival and growth of juveniles of D. avara and C. crambe transplanted to the sea to compare laboratory and field results. The results altogether indicated that sponge culture from larvae is a promising method for sponge supply and that laboratory culture under controlled conditions is preferred over sea cultures in order to prevent biomass losses during these early life stages.     

Inhibitory Effects of a Branched-Chain Fatty Acid on Larval Settlement of the Polychaete Hydroides elegans

Eleven strains of Streptomyces isolated from deep-sea sediments were screened for anti-larval settlement activity and all were active. Among those strains, Streptomyces sp. UST040711-290 was chosen for the isolation of bioactive antifouling compounds through bioassay-guided isolation procedure. A branched-chain fatty acid, 12-methyltetradecanoid acid (12-MTA) was purified, and it strongly inhibited the larval settlement of the polychaete Hydroides elegans. Streptomyces sp. UST040711-290 produced the highest yield of 12-MTA when the bacterium was cultured at 30°C and pH 7.0 in a modified MGY medium. To investigate the potential antifouling mechanism of 12-MTA in the larval settlement of Hydroides elegans, the expression level of four marker genes, namely, Ran GTPase activating protein (GAP), ATP synthase (AS), NADH dehydrogenase (ND), and cell division cycle protein (CDC), was compared among the untreated larvae (the control), isobutylmethylxanthine (an effective settlement inducer), and 12-MTA-treated larvae. The 12-MTA treatment down-regulated the expression of GAP and up-regulated the expression of AS in the H. elegans larvae, but did not affect the expression of ND and CDC. This study provides the first evidence that a branched-chain fatty acid produced by a marine bacterium isolated from deep-sea sediment effectively inhibited the larval settlement of the biofouling polychaete H. elegans and its effects on the expression of genes important for larval settlement.     

Antifouling Activity of Bromotyrosine-Derived Sponge Metabolites and Synthetic Analogues

Eighteen brominated sponge-derived metabolites and synthetic analogues were analyzed for antilarval settlement of Balanus improvisus. Only compounds exhibiting oxime substituents including bastadin-3 (4), −4 (1), −9 (2), and −16 (3), hemibastadin-1 (6), aplysamine-2 (5), and psammaplin A (10) turned out to inhibit larval settling at 1 to 10 μM. Analogues of hemibastadin-1 (6) were synthesized and tested for structure activity studies. Debromohemibastadin-1 (8) inhibited settling of B. improvisus, albeit at lower concentrations than hemibastadin-1 (6). Both 6 and 8 also induced cyprid mortality. 5,5′-dibromohemibastadin-1 (7) proved to be nontoxic, but settlement inhibition was observed at 10 μM. Tyrosinyltyramine (9), lacking the oxime function, was not antifouling active and was non-toxic at 100 μM. Hemibastadin-1 (6) and the synthetic products showed no general toxicity when tested against brine shrimp larvae. In contrast to the lipophilic psammaplin A (10), the hydrophilic sulfated psammaplin A derivative (11) showed no antifouling activity even though it contains an oxime group. We therefore hypothesize that the compound needs to cross membranes (probably by diffusion) and that the target for psammaplin A lies intracellularly.     

Activity of Commercial Enzymes on Settlement and Adhesion of Cypris Larvae of the Barnacle Balanus amphitrite,Spores of the Green Alga Ulva linza,and the Diatom Navicula perminuta

Fouling species produce adhesive polymers during the settlement, adhesion and colonization of new surfaces in the marine environment. The present paper tests the hypothesis that enzymes of the appropriate specificity may prevent biofouling by hydrolysing these adhesive polymers. Seventeen commercially available enzyme preparations designed originally for bulk use in a range of end-use applications were tested for their effects on the settlement and/or adhesion of three major fouling species, viz. the green alga Ulva linza, the diatom Navicula perminuta and the barnacle Balanus amphitrite. The serine-proteases were found to have the broadest antifouling potential reducing the adhesion strength of spores and sporelings of U. linza, cells of N. perminuta and inhibiting settlement of cypris larvae of B. amphitrite. Mode-of-action studies on the serine-protease, Alcalase, indicated that this enzyme reduced adhesion of U. linza in a concentration-dependent manner, that spores of the species could recover their adhesive strength if the enzyme was removed and that the adhesive of U. linza and juvenile cement of B. amphitrite became progressively less sensitive to hydrolysis as they cured.     

Life History of the Barnacle Balanus Amphitrite Darwin and Its Role in Fouling Communities of Peter the Great Bay, Sea of Japan

The life history of the barnacle Balanus amphitrite Darwin and its role in fouling communities of Golden Horn Bay (Peter the Great Bay), which is subjected to thermal pollution, were studied. The warm-water B. amphitrite occurs as a common minor species on operational vessels and waterworks in Peter the Great Bay, where it was brought by ocean-going ships operating on Russia–Japan lines. Even in the conditions of the higher temperature regime of Golden Horn Bay, the reproductive season of B. amphitrite is confined to the summer and autumn months. The adult individuals brought by ships in summer produce 2–3 generations of larvae. The development of larvae and their settling on the substrate occurs from August to October within a broad temperature range from 22.5 up to 12°C. Even in the low temperatures of Golden Horn Bay the larvae attain a greater size than those in tropical and subtropical waters. The juveniles have time to reach maturity and to produce their own progeny, but most often they perish with winter drop in the water temperature. It was shown that in Peter the Great Bay there is dependent population of B. amphitrite inhabiting the anthropogenic substrates only in the warm season: water works, idle vessels, and operational offshore vessels. The water temperature is the limiting factor of successful acclimation of that species.     

Effects of surface charge and Gibbs surface energy on the settlement behaviour of barnacle cyprids (Balanus amphitrite)

Gibbs surface energy has long been considered to be an important parameter in the design of fouling-resistant surfaces for marine applications. Rigorous testing of the hypothesis that settlement is related to Gibbs surface energy however has never been accomplished, due mainly to practical limitations imposed by the necessary combination of surface engineering and biological evaluation methods. In this article, the effects of surface charge and Gibbs surface energy on the settlement of cyprids of an important fouling barnacle, Balanus amphitrite, were evaluated. Settlement assays were conducted on a range of self-assembled monolayers (SAMs) (CH₃-, OH-, COOH-, N(CH₃)₃ ⁺-, NH₂-terminated), presented in gold-coated polystyrene well plates, varying in terms of their surface charge and Gibbs surface energy. Contrary to contemporary theory, settlement was not increased by high-energy surfaces, rather the opposite was found to be the case with cyprids settling in greater numbers on a low-energy CH₃- SAM compared to a high-energy OH- SAM. Settlement was also greater on negatively-charged SAMs, compared to neutral and positively-charged SAMs. These findings are discussed in the context of data drawn from surfaces that varied in multiple characteristics simultaneously, as have been used previously for such experiments. The finding that surface charge, rather than total surface energy, may be responsible for surface selection by cyprids, will have significant implications for the design of future fouling-resistant materials.     

The impact of food type, temperature and starvation on larval development of Balanus amphitrite Darwin (Cirripedia: Thoracica)

The impact of diatom food species (Chaetoceros calcitrans and Skeletonema costatum), temperature and starvation on the larval development of Balanus amphitrite was evaluated. Starvation threshold levels for different ages of larvae (0- to 5-day-old) fed with C. calcitrans and S. costatum and then starved at 5, 15 and 25 °C temperature were estimated as ultimate recovery hour (URH; denoting the starvation point in hours at the end of which larvae can recover and continue development). Effect of temperature on starvation threshold varied significantly with larval age and food species. The URH declined with larval age at 5 °C, but not at 15 and 25 °C. The URH and grazing rates were high for early instars fed on C. calcitrans, and for advanced instars fed on S. costatum. Carbon gain through feeding was maximum for 2-day-old larvae when fed with C. calcitrans and decreased with larval age. However, when fed with S. costatum carbon gain increased with larval age. This confirms that with development the utility of food types changes. The differences in the carbon gain can be attributed to differences in grazing rate due to variations in the size of the diatom cells, larval intersetular distance, diatom sinking rate and the photo-taxic behavior of larvae. Molting was observed at times when larvae were undergoing starvation and this could be viewed as stress-induced molting, and it differed with the larval age and food organisms.     

滇重楼内生真菌Aspergillus fumigatus代谢产物的研究

为研究滇重楼内生真菌Aspergillus fumigatus的代谢产物,采用多种色谱分离技术对其菌丝体和发酵液进行分离纯化,得到31个化合物。根据理化性质及波谱数据,结构分别鉴定为tryprostatin B (1)、tryprostatin A (2)、12,13-dihydroxyfumitre- morgin C (3)、cyclotryprostatin B (4)、14-norpseurotin A (5)、pseurotine F1 (6)、pseurotine F2 (7)、azaspirofuran A (8)、pseurotin D (9)、spirotryprostatin K (10)、6-methoxyspirotryprostatin B (11)、deacetylpyripyropene A (12)、烟曲霉素 (13)、fuma- gillene A (14)、5,9-dihydroxy-β-trans-bergamotene (15)、对羟基苯乙酸 (16)、demethoxyfumitremorgin C (17)、fumiquinazoline J (18)、烟曲霉酸 (19)、麦角甾醇 (20)、过氧麦角甾醇 (21)、4,4-dimethyl-5α-ergosta-8,24(28)-dien-3β-ol (22)、羊毛甾醇 (23)、亚油酸 (24)、油酸 (25) 、烟曲霉毒素C (26)、烟曲霉毒素B (27)、震颤真菌毒素 (28)、pseurotin A (29)、fumiquinazoline C (30)和questin (31)。其中,化合物1~16仅从发酵液中分离得到;化合物17~25仅从菌丝体中分离得到;其余化合物在发酵液和菌丝体中均分离得到。化合物15和23为首次从烟曲霉属真菌中分离得到。此外,化合物26~29的乙酰胆碱酯酶抑制活性和烟草黑胫病菌抑制活性评价表明,化合物26和27对烟草黑胫病菌具有微弱的抑制作用,抑菌率分别为19.64%和17.86%。     

K~(+)、Cr~(6+)对网纹藤壶幼虫发育和存活的影响

以华南沿海污损生物群落优势种网纹藤壶(Balanus reticulatus)的幼虫为研究对象,探讨钾、铬2种金属离子对其幼虫存活及发育的影响。实验所用金属离子溶液是将K+和Cr6+母液添加到过滤消毒海水中配制。将活泼健壮的网纹藤壶无节幼虫置于上述溶液中,以亚心形扁藻(Platymonas subcordiformis)为饵料于30℃左右的黑暗环境中培养5d,镜检观察记录幼虫发育状况并进行统计分析。结果表明,K+对网纹藤壶幼虫发育和存活的影响均不明显;而Cr6+对幼虫发育具有一定的毒杀和抑制作用,不仅幼虫存活率低于对照组,而且金星幼虫所占百分率也低于对照组。     

Temporal Fluctuations and Settlement Patterns of Native and Lessepsian Herbivorous Fishes on the Lebanese Coast (Eastern Mediterranean)

We provide here the first information on the abundance, settlement patterns and microhabitat use of settlers of two Lessepsian siganid species, Siganus rivulatus and S. luridus, in comparison with the two main native herbivores, Sparisoma cretense (Scaridae) and Sarpa salpa (Sparidae). S. rivulatus was the most abundant species (72%), followed by S. cretense (20%) and S. luridus (8%), whereas S. salpa was rare (<1%). A clear pattern of settlement could be established for S. rivulatus and S. cretense, with similar timing in 1999 and 2000. S. cretense settled in schools late June, while S. rivulatus settled mid-July. A few solitary settlers of S. luridus were observed in July and August, but none of S. salpa. All these herbivorous fish species settled in protected shallow areas offering hard substrates and algal communities. S. rivulatus was the most tolerant and adaptable species, able to settle on a large range of substrates and habitats, including rock pools, muddy harbours and sea grass beds. In the eastern Mediterranean Sea, S. rivulatus might have benefited from a release of competition pressure due to the low diversity and abundance of native herbivores. It has probably replaced S. salpa on the coast of Lebanon, being more competitive than the native sparid.     

白花丹素对E.coli藻酸盐合成的抑制作用

细菌分泌的胞外多糖在生物被膜的形成和发展过程中发挥着重要作用。通过测定白花丹素对大肠埃希菌10389菌株(E.coli 10389)藻酸盐合成的影响及其对rse A和rpo E基因表达量的影响,探讨白花丹素对大肠埃希菌生物被膜(biofilm,BF)形成的抑制作用及机制。研究结果显示,白花丹素能抑制E.coli 10389生物被膜的形成,其抑杀E.coli 10389的最低抑菌浓度(minimum inhibitory concentration,MIC)和最低杀菌浓度(minimal bactericidal concentration,MBC)分别为16和64μg/mL。白花丹素对成熟BF内的细菌也有抑制和杀灭作用,其抑杀E.coli 10389成熟BF内细菌的MIC和MBC分别为64和128μg/mL。白花丹素能够抑制E.coli 10389藻酸盐的合成,其中1/2MIC的白花丹素作用E.coli 10389 24 h后,与对照组比,藻酸盐的合成量降低了34.83%(P0.01)。白花丹素可显著影响E.coli 10389 rse A和rpo E基因的相对表达量,其中1/2MIC的白花丹素作用E.coli 10389 24 h后,与对照组相比,rse A的表达量上调了17.43%,rpo E的表达量降低了12.8%(P0.05)。结果表明,白花丹素能够抑制E.coli 10389 BF的形成,其作用机制可通过影响rse A和rpo E的基因表达量,进而抑制藻酸盐的合成来抑制大肠埃希菌生物被膜的形成。     

Genetic diversity and phylogenetic position of the subclass Astomatia (Ciliophora) based on a sampling of six genera from West African oligochaetes (Glossoscolecidae, Megascolecidae), including description of the new genus Paraclausilocola n. gen

To more confidently assess phylogenetic relationships among astome ciliates, we obtained small subunit (SSU) rRNA sequences from nine species distributed in six genera and three families: Almophrya bivacuolata, Eudrilophrya complanata, Metaracoelophrya sp. 1, Metaracoelophrya sp. 2, Metaracoelophrya intermedia, Metaradiophrya sp., Njinella prolifera, Paraclausilocola constricta n. gen., n. sp., and Paraclausilocola elongata n. sp. The two new species in the proposed new clausilocolid genus Paraclausilocola n. gen. are astomes with no attachment apparatus, two files of contractile vacuoles, and an arc-like anterior suture that has differentiations of thigmotactic ciliature on the anterior ends of the left kineties of the upper surface. Phylogenetic analyses were undertaken using neighbor-joining, Bayesian inference, maximum likelihood, and maximum parsimony. The nine species of astomes formed a strongly supported clade, showing the subclass Astomatia to be monophyletic and a weakly supported sister clade to the scuticociliates. There were two strongly supported clades within the astomes. However, genera assigned to the same family were found in different clades, and genera assigned to the same order were found in both clades. Thus, astome taxa appear to be paraphyletic when morphology is used to assign species to genera.     

Comparison of the Effects of Antidepressants and Their Metabolites on Reuptake of Biogenic Amines and on Receptor Binding

1. The present survey compares the effects of antidepressants and their principal metabolites on reuptake of biogenic amines and on receptor binding. The following antidepressants were included in the study: the tricyclic antidepressants amitriptyline, dothiepin, and lofepramine and the atypical antidepressant bupropion, which all have considerable market shares in the UK and/or US markets; the selective serotonin reuptake inhibitors (SSRIs) citalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline; and the recently approved antidepressants venlafaxine and nefazodone.2. Amitriptyline has similar in vitro reuptake inhibitory potencies for 5-HT and NA, whereas the metabolite nortriptyline is preferentially a NA reuptake inhibitor. Both amitriptyline and nortriptyline are also 5-HT₂ receptor antagonists.3. Dothiepin has equipotent 5-HT and NA reuptake inhibitory activity, whereas northiaden shows a slight selectivity for NA reuptake inhibition. Dothiepin and northiaden are also 5-HT₂ receptor antagonists. The slow elimination rate of northiaden (36–46 hr) compared to dothiepin (14–24 hr) suggests that northiaden contributes significantly to the therapeutic effect of dothiepin.4. Lofepramine is extensively metabolized to desipramine. Desipramine plays an important role in the antidepressant activity of lofepramine, as the plasma elimination half-life of lofepramine (4–6 hr) is much shorter than that of desipramine (24 hr). Both compounds are potent and selective inhibitors of NA reuptake.5. The five approved SSRIs, citalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline, are potent 5-HT reuptake inhibitors, and the demethyl metabolites, norfluoxetine, demethylsertraline, and demethylcitalopram, also show selectivity. Paroxetine and sertraline are the most potent inhibitors of 5-HT reuptake, whereas citalopram is the most selective. Fluoxetine is the least selective and the metabolite of fluoxetine, norfluoxetine, is a more selective and more potent 5-HT reuptake inhibitor than the parent compound and has an extremely long half-life (7–15 compared to 1–3 days). Thus the metabolite plays an important role for the therapeutic effect of fluoxetine. Fluoxetine is also a 5-HT_2C receptor antagonist. Demethylsertraline is a weaker and less selective 5-HT reuptake inhibitor in vitro than sertraline, but demethylsertraline has a very long half-life (62–104 hr) compared to the parent compound (24 hr) and it might play a role in the therapeutic effects of sertraline. Demethylcitalopram has about a 10 times lower 5-HT reuptake inhibitory potency in vitro than citalopram, and the elimination half-lives are approximately 1.5 and 2 days, respectively.6. Bupropion and hydroxybupropion are weak inhibitors of biogenic amine reuptake. The mechanisms of action responsible for the clinical effects of bupropion are not fully understood, but it has been suggested that both dopaminergic and noradrenergic components play a role and that the hydroxybupropion metabolite contributes significantly to the antidepressant activity.7. Venlafaxine and O-demethylvenlafaxine are weak inhibitors of 5-HT and NA reuptake, and the selectivity ratios are close to one. O-Demethylvenlafaxine is eliminated more slowly than venlafaxine (plasma half-lives of 5 and 11 hr, respectively), and it is likely that it contributes to the overall therapeutic effect of venlafaxin.8. Nefazodone and -hydroxynefazodone are equipotent 5-HT and NA reuptake inhibitors. Both compounds are also 5-HT₂ receptor antagonists. Both parent compound and metabolite have short elimination half-lives.     

Toxoplasma gondii: Inhibitory activity and encystation effect of securinine and pyrrolidine derivatives on Toxoplasma growth

Securinine, an alkaloid originally isolated from Securinega suffruticosa, exhibits a wide range of biological activities, including anti-malarial activity. Along with securinine, 10 pyrrolidine derivatives, generated via the retrosynthesis of (−)-securinine, were selected and tested for their inhibitory activity against Toxoplasma gondii growth in vitro. Anti-Toxoplasma activity correlated to hydrophobicity of the tested compounds. Three pyrrolidine derivatives along with securinine inhibit Toxoplasma proliferation at the micromolar range. These compounds act on parasite proliferation in different capacities, either by slowing the growth rate or inhibiting invasion of host cells. Securinine induces bradyzoite differentiation at comparable levels to treatment with alkali media in vitro.     

Effects of ricinoleic acid esters from castor oil of Ricinus communis on the vitellogenesis of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) ticks

This study examines the effects of ricinoleic acid esters from Ricinus communis castor oil on the vitellogenesis of Rhipicephalus sanguineus ticks attached to hosts that were fed with commercial rabbit food containing these esters. The oocytes of ticks from the treatment group (TG) showed cytoplasmic changes that inhibited the development of oocytes I and II to the advanced stages (IV and V) in addition to preventing the maturation of oocytes V, resulting in small ones. In addition, sperm was not observed in ampoules. Our findings confirm the acaricide potential of ricinoleic acid esters.     

中国林蛙与中华蟾蜍蝌蚪颅骨形态的系统进化比较

对无尾两栖动物系统进化的研究,主要是基于经典的形态学、现代分子生物学等技术。无尾两栖动物蝌蚪的进化与成体的进化可能是两个独立的过程,所以无尾两栖类蝌蚪形态及发育特征也可以作为研究系统进化的重要指征。本文对中国林蛙(Rana chensinensis)及中华蟾蜍(Bufo gargarizans)变态前蝌蚪的软骨性颅骨及鳃部骨骼进行形态学描述,基于幼体形态特征,进行系统建树。建树结果支持Orton将无尾两栖类蝌蚪划分为4种类型,认为最原始的类群为Ⅲ型蝌蚪,与Tihen的观点一致。新蛙亚目的中国林蛙和中华蟾蜍蝌蚪属Ⅳ型,是最进化的类群。     

徐闻普哥滨珊瑚土曲霉XWC21-10代谢产物活性及其活性物质的研究

为了开发利用海洋活性天然产物,对分离自普哥滨珊瑚的1株土曲霉XWC21-10次级代谢产物的活性及其活性成分进行初步研究。结果表明,该菌株发酵液的4种萃取物对6种指示菌均有明显的抑菌活性,说明具有广谱抑菌作用;菌丝体氯仿萃取物和发酵液乙酸乙酯萃取物对乙酰胆碱酯酶(Ach E)抑制作用最为明显,抑制率分别达到(79.37±1.53)%,(67.04±1.96)%。对具有明显活性的乙酸乙酯萃取物经硅胶柱层析分离得到11个级分。活性跟踪检测组分6、7、8、11活性较好,组分6、7成分相似,其主要含有还原性物质、高级醇、甾类等化合物;而级分11仅含有共轭基团化合物,成分相对简单。因此,该菌代谢产物具有良好的抑菌和抑制乙酰胆碱酯酶活性,活性物质还有待进一步的纯化和确定,该研究可为开发抑菌剂和治疗早老性痴呆症提供基础。     

Importance of Nutrient Competition and Allelopathic Effects in Suppression of the Green Alga Scenedesmus obliquus by the Macrophytes Chara, Elodea and Myriophyllum

Possible allelopathic effects of substances released from the macrophytes Chara globularis, Elodea canadensis, Myriophyllum spicatum on the common green alga Scenedesmus obliquus were tested in the laboratory with plastic plants and untreated medium as controls. A two-phase approach was used in which first the effects of physical presence of plants was studied (phase I) followed by the effects of plant culture filtrates (phase II). In the presence of plastic plants growth was reduced only marginally, but strong growth inhibition of Scenedesmus occurred in the physical presence of all macrophytes. In contrast, filtrates from Chara had no growth inhibitory effect on Scenedesmus. Myriophyllum filtrate reduced particle-based growth rate by 7% compared to filtration controls, while Elodea culture filtrate reduced volume-based growth by 12%, chlorophyll-based growth by 28% and particle-based growth by 15%. Photosystem II-efficiency of Scenedesmus was reduced in all three macrophyte treatments in phase I, but not in filtrates from macrophyte cultures (phase II). Thus, while enzyme activity or other physiological aspects may have been affected, the current study yielded no proof for allelopathically active compounds being directed at photosynthesis. Mean particle volume (MPV) of Scenedesmus was not influenced by macrophyte exudates and cultures remained dominated by unicells. The strong growth inhibitory effects found for Scenedesmus in the physical presence of macrophytes, but not in plastic controls, and no or weaker response in nutrient-enriched filtrates, suggest nutrient competition was a more powerful driving factor than allelochemicals. However, the experimental design does not exclude disappearance of allelochemicals during the filtration process.     

Effects of Ricinus communis oil esters on salivary glands of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae)

This study showed the interference of esters extracted from Ricinus communis in the secretory cycle of salivary glands of Rhipicephalus sanguineus ticks, which consequently caused collateral effects on their feeding process. Ticks attached on hosts which were fed with commercial feed containing different concentrations of R. communis oil esters suffered damages such as cytoplasmic changes in their salivary glands, notably in the acinar cells, impairing the functioning of the acini and accelerating the organs degeneration as a whole. It was found that esters interfered with the activity of cellular secretion by changing the glycoprotein of salivar composition especially in acini II cells. It was also shown that the damages caused by esters in the salivary glands cells of these ectoparasites increased in higher concentrations of the product and degenerative glandular changes were more pronounced.     

Evaluation and application of aquatic toxicity tests: use of the Microtox test for the prediction of toxicity based upon concentrations of contaminants in soil

The quality control for the reuse of cleaned soil from a contaminated site consisted in the determination of the main contaminants by analytical chemical methods such as GC and HPLC. Since it is not possible to analyze for all contaminants a toxicity test should be used to detect large concentrations of not routinely analyzed chemicals. The aim of the study was to develop a system for toxicity testing, which should be able to predict the toxicity of soil samples based on the concentration of chemicals in the soil and to detect toxic chemicals not analyzed by the routinely conducted soil analysis.Based upon the relative sensitivity to various contaminants as well as practical aspects such as test duration and costs the Microtox® test was favoured over the bioassays with Daphnia magna and Scenedesmus subspicatus. The Microtox® test was used to measure the toxicity of various pesticides and their major metabolites. The toxicity data of the pure compounds were used to predict the toxicity (EC₅₀ and % inhibition of the bioluminescence reaction) of defined mixtures of chemicals in water by applying two different mathematical appriaches which are based on the additivity of the effects of the single chemicals. The predicted values were compared with the experimental data and showed good agreement.In order to be able to predict the toxicity of soil samples using the Microtox® test the soil/water partition coefficient (K _d) was measured for the main contaminants. The toxicity of soil samples was predicted by calculating the concentration of the contaminants in the leachate by using the corresponding concentration in the soil and applying the K _d values determined. From the calculated composition of the leachate the expected toxicity was estimated. This value was compared with the toxicity experimentally determined in the Microtox® test.