Development of sensitive and specific multiplex PCR method for the detection of microcystin producing cyanobacteria in spirulina food supplements

Cyanotoxins in food: Exposure assessment and health impact

The intricate nature of cyanotoxin exposure through food reveals a complex web of risks and uncertainties in our dietary choices. With the aim of starting to unravel this intricate nexus, a comprehensive review of 111 papers from the past two decades investigating cyanotoxin contamination in food was undertaken. It revealed a widespread occurrence of cyanotoxins in diverse food sources across 31 countries. Notably, 68% of the studies reported microcystin concentrations exceeding established Tolerable Daily Intake levels. Cyanotoxins were detected in muscles of many fish species, and while herbivorous fish exhibited the highest recorded concentration, omnivorous species displayed a higher propensity for cyanotoxin accumulation, exemplified by Oreochromis niloticus. Beyond fish, crustaceans and bivalves emerged as potent cyanotoxin accumulators. Gaps persist regarding contamination of terrestrial and exotic animals and their products, necessitating further exploration. Plant contamination under natural conditions remains underreported, yet evidence underscores irrigation-driven cyanotoxin accumulation, particularly affecting leafy vegetables. Finally, cyanobacterial-based food supplements often harbored cyanotoxins (57 % of samples were positive) warranting heightened scrutiny, especially for Aphanizomenon flos-aquae-based products. Uncertainties surround precise concentrations due to methodological variations (chemical and biochemical) and extraction limitations, along with the enigmatic fate of toxins during storage, processing, and digestion. Nonetheless, potential health consequences of cyanotoxin exposure via contaminated food include gastrointestinal and neurological disorders, organ damage (e.g. liver, kidneys, muscles), and even elevated cancer risks. While microcystins received significant attention, knowledge gaps persist regarding other cyanotoxins' accumulation, exposure, and effects, as well as combined exposure via multiple pathways. Intriguing and complex, cyanotoxin exposure through food beckons further research for our safer and healthier diets.

Spatio-temporal variation of toxin-producing gene abundance in Microcystis aeruginosa from Poyang Lake

Microcystis aeruginosa (M. aeruginosa) causes massive blooms in eutrophic freshwater and releases microcystin. Poyang Lake is the largest freshwater lake in China and has kept a mid-nutrient level in recent years. However, there is little research on microcystin production in Poyang Lake. In this study, water and sediment samples from ten sampling sites in Poyang Lake were collected from May to December in 2020, and from January to April in 2021 respectively. Microcystis genes (mcyA, mcyB, 16 s rDNA) were quantified by real-time fluorescence quantitative PCR analysis, and then the spatial and temporal variation of mcy genes, physicochemical factors, and bacterial population structure in the lake was analyzed. The relationship between the abundance of mcy genes and physicochemical factors in water column was also revealed. Results indicated that the microcystin-producing genes mcyA and mcyB showed significant differences in spatial and temporal levels as well, which is closely related to the physicochemical factors especially the water temperature (p < 0.05) and the nitrogen content (p < 0.05). The abundance of mcy genes in the sediment in December affected the abundance of mcy genes in the water column in the next year, while the toxic Microcystis would accumulate in the sediment. In addition to the toxic Microcystis, we also found a large number of non-toxic Microcystis in the water column and sediment, and the ratio of toxic to non-toxic species can also affect the toxicity production of M. aeruginosa. Overall, the results showed that M. aeruginosa toxin-producing genes in Poyang Lake distributed spatially and temporally which related to the physicochemical factors of Poyang Lake.

Clinical-pharmacological drug information center of Hannover Medical School: experiences and analysis from a tertiary care university hospital

Drug information centers (DICs) are institutions dedicated to provide objective, independent, and up-to-date information on drugs and their rational use. To overcome the lack of recent DIC reports from central Europe, we analyzed all queries (n = 594) submitted to the DIC run by the Institute for Clinical Pharmacology of Hannover Medical School between October 2018 and April 2022. Approximately one in three queries (31.1%; 185/594) was submitted by internists. 82.8% (492/594) of the queries were patient-specific, while the remaining 17.2% (102/594) were general queries. Adverse drug reactions (ADRs), indications/contraindications, and pharmacodynamic interactions (PDIs) represented the three most frequently addressed query categories, being involved in 44.8% (266/594), 43.3% (257/594), and 34.3% (204/594) of all queries, respectively (assignment of more than one category per query was possible). As compared to general queries, patient-specific queries were statistically significantly more often related to ADRs, PDIs, and pharmacokinetic interactions (PKIs) (ADRs: 35.3% vs. 46.7%, P = 0.034; PDIs: 14.7% vs. 38.4%, P < 0.001; PKIs: 20.6% vs. 31.5%, P = 0.028). To demonstrate the complexity of queries submitted to the clinical-pharmacological DIC, we present and comment on an illustrative selection of queries.

Rapid detection of mcyG gene of microcystins producing cyanobacteria in water samples by recombinase polymerase amplification combined with lateral flow strips

Nowadays, cyanobacteria blooms and microcystins (MCs) pollution are threatening water safety and public health. In this study, a rapid detection method was established for detecting MCs producing cyanobacteria. The MC synthesis gene mcyG was measured through recombinase polymerase amplification combined with lateral flow strips (LF-RPA) technology. The target gene mcyG was amplified at a temperature range of 37-45 °C, and the amplification time to detect mcyG was only 15 min at 37 °C. The optimal reaction conditions were confirmed using single dependent variable experiments, suggesting that the best probe dosage for 50 μL of the reaction mixture was 0.2 μL, the best dilution ratio of products was 1/100, and the best loading volume was 10 μL. The specificity test proved that the LF-RPA assay could distinguish MCs producing cyanobacteria from nontoxic algae well. Within 35 min of amplification time, the detection limit of the LF-RPA assay was 10³ copies/mL mcyG and 10⁴ cells/mL Microcystis aeruginosa FACHB-905. Overall, the LF-RPA assay could detect MCs producing cyanobacteria in water samples quickly and accurately, and it has a great promise to be applied for monitoring the MCs producing cyanobacteria blooms in natural waters.

Multi-Class UHPLC-MS/MS Method for Plant Toxins and Cyanotoxins in Food Supplements and Application for Belgian Market Samples

The presence of plant toxins and/or cyanotoxins in food supplements implies consumer health risks. Therefore, a targeted ultra-high performance liquid chromatographic-tandem mass spectrometric method to detect/quantify 25 toxins simultaneously in food supplement formulations was developed and validated. Full validation for tablets/powders and secondary validation for a liquid and soft gel capsule indicated that most compounds were efficiently extracted (≥ 75%), while others were only partly extracted (18 - 61%). Trueness was fulfilled (70 - 120%), with some exceptions (mostly at the lowest validation level). Intralaboratory repeatability, intra- and interlaboratory reproducibility values of ≤ 20%, ≤ 25%, and ≤ 25% were obtained for most, respectively. Matrix effects were found to be significant for most compounds. Good sensitivity (µg/kg level) was observed for galegin(e), lycopsamine, lycorine, rubiadin, skimmiamine, and vascin(e), in contrast to helveticoside, lucidin, lucidin-3-primveroside, plumbagin(e), and thujone, which were detected at the mg/kg level. The other compounds were characterized by a sensitivity between 10 to 1000 µg/kg. The validated methodology was applied for 52 food supplements (tablets, capsules, liquids/syrup, etc.) purchased from the Belgian market. In more than 25% of the samples, one or more toxins were detected (concentrations determined using standard addition). Lycopsamine, microcystin LR, solamargine, thujone, and vasicin(e) were the most frequently detected toxins. A clear link between the toxins detected and the plant species on the food supplement ingredient list could not always be established. This generic "dilute-and-shoot" procedure can be used for further research on toxins in food supplements and by extension other plant/algae-based food/feed commodities (herbs, edible flowers, etc.).