A rapid microbiotest for the detection of cyanobacterial toxins

Abstract

Cyanobacteria occur widely in lakes, reservoirs, ponds, and slow flowing rivers. Many species are known to produce toxins (cyanotoxins), a number of which are of concern for health. Cyanotoxins vary in chemical structure and may be found intracellular or released into water. There is not only a wide variation in the toxicity of known cyanotoxins but a substantial number of toxins have to date not been identified chemically. Chemical analysis of cyanotoxins is nowadays not used for routine monitoring because it is time consuming, it requires specialized equipment and expertise, and is hence expensive. There is hence an urgent need for rapid tests in surface waters to detect cyanobacterial toxins because of the need for safe drinking water and safe natural bathing waters, which may be burdened by cyanobacterial blooms or scums. Previous investigations have already shown that larvae of the anostracan crustacean Thamnocephalus platyurus are quite sensitive to neurotoxic and hepatotoxic cyanotoxins. The present paper reports on the sensitivity comparison of the (1 h) Rapidtoxkit (based on a sublethal endpoint) and the (24 h) Thamnotoxkit microbiotest (based on mortality). Both assays make use of larvae of T. platyurus. The Rapidtoxkit is a new microbiotest that determines the decrease of ingestion of colored particles by the crustacean larvae, which are stressed by a short exposure to toxicants. Fifteen cyanobacterial samples composed of laboratory strains and natural bloom samples were tested by both microbiotests. All samples were also analyzed concurrently by HPLC for microcystins and cylindrospermopsin. The correlation coefficient between the two microbiotests (r ¼ 0.82) showed the very good correspondence between the sublethal and the lethal effects. No known toxins could be detected in some samples, although the latter were found highly toxic to the test organisms in both bioassays. These results point to the presence of unknown toxin(s) produced by some cyanobacteria such as e.g., the Cylindrospermopsis raciborskii strain isolated from Lake Balaton in Hungary. This comparative study clearly showed that the 1 h Rapidtoxkit is an attractive rapid alternative to the Thamnotoxkit microbiotest. # 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 64-68, 2007.

Unsubstituted <i>β</i>-Alkyl Aspartates as Highly Biodegradable and Almost Nontoxic Surfactants

“…The toxicity values observed in the ingestion tests were very close to the mortality values. A strong correlation was reported between the two microbiotests performed with Thamnocephalus platyurus (Rapidtoxkit and Thamnotoxkit); a very good correspondence between the sublethal and the lethal effects, respectively was shown [19]. Therefore, the use of Rapidtoxkit for evaluating a potential toxicity of our investigated surfactants (2) can be considered as suitable.…”

“…Rapidtoxkit microbiotest was applied for evaluating the toxic effect of β-dodecyl aspartate (2b) on freshwater crustacean T. platyurus. As a guideline, 30% inhibition of particle uptake was suggested as "a threshold signal" for the presence of "unwanted compounds" in the water sample [18] [19]. NałęczJawecki and coworkers [18] have compared the results on sodium dodecyl sulphate toxicity obtained in: 1) 60 min sublethal assay with anostracan crustaceans Thamnocephalus platyurus and 2) 24 h lethality assays with rotifers Brachionus calyciflorus.…”

Determination of the toxicity of the freshwater cyanobacterium Woronichinia naegeliana (Unger) Elenkin

“…These may be the most probable reasons why an application of bioassays for evaluation of the bioactivity of all secondary metabolites synthesized by cyanobacteria increases in time. Additionally, relatively simple procedures keep the costs of these routinely performed analyses relatively low (Törökné et al 2007). …”

Nodularia spumigena Peptides—Accumulation and Effect on Aquatic Invertebrates

“…In preliminary assessments of cyanobacterial toxicity, the commercially available biotests on commonly occurring zooplankton crustaceans have been frequently used [ 5 , 36 ]. The tests constitute an attractive alternative, free from ethical constrains, for bioassays performed on vertebrates [ 37 , 38 ].…”