Chlortetracycline and related tetracyclines: detection in wheat and rye grain.

BACKGROUND: Antibiotic drugs are excreted to a large proportion by livestock. Thus, antibiotics are distributed on fields with slurry and can be taken up by plants. In the present study, hydroponic experiments were performed to reveal whether the widely administered chlortetracycline is taken up into wheat grain in a concentration-dependent manner. A further goal was to determine (chlor)tetracyclines in wheat and rye grain from agricultural practice. RESULTS: Increasing chlortetracycline deposition in wheat grain was observed with a rising chlortetracycline spiking level in the hydroponic solution. In 371 selected wheat and rye samples from three growing years of agricultural practice, the overall detection frequency was 21% for tetracyclines. In the most highly contaminated sample, tetracyclines occurred at 18.2 µg kg-1 . Tetracycline residues were also found in rye grain. Conversion and degradation products of (chlor)tetracycline such as tetracycline, doxycycline and demeclocycline were detected in grains from hydroponic experiments and from agricultural practice. CONCLUSION: Concentrations of tetracyclines found in wheat and rye grains were of no concern with respect to toxicity regarding human consumption. However, antibiotic concentrations below the minimum inhibitory concentration can select for antibiotic resistance in bacteria. Thus, low levels of different tetracycline residues contained in food should be taken into account regarding risk assessment. © 2018 Society of Chemical Industry.

Pyrrolizidine alkaloids and tropane alkaloids in milk samples from individual dairy farms of the German federal states of Bavaria and Schleswig-Holstein.

1,2-Dehydro-pyrrolizidine alkaloids (PA), their corresponding N-oxides (PANO) and tropane alkaloids (TA), are toxic plant metabolites. If plant material, containing these toxins, is present in the feed of dairy cows these toxins can be transferred into milk. Here, milk was sampled directly from dairy farms in the German federal states of Bavaria and Schleswig-Holstein in 2020-2022 in order to investigate a possible contamination of milk at the production stage. In total, 228 milk samples were analysed for 54 PA/PANO and two TA by a sensitive LC-ESI-MS/MS method. In addition, a subset of milk samples (n = 85) was independently analysed for TA by a cooperating laboratory for verification. PA/PANO were found in 26 samples (11%) with a low median sum content of the contaminated samples of 0.024 µg/L. The highest level of contamination was 5.6 µg/L. Senecionine-, lycopsamine- and heliotrine-type PA/PANO were detected. In four samples (1.8%), atropine was determined up to 0.066 µg/L. The toxin levels in the milk samples hardly contributed to the total daily exposure. These data are first-time results on contamination rates and levels occurring in milk from individual dairy farms, based on a large sample number.

Relevance of Zearalenone and its modified forms in bakery products.

Zearalenone is a frequently occurring and well-known mycotoxin developed in cereals before and during the harvest period by Fusarium spp. mainly in maize and wheat. In addition to the main form, various modified forms (phase I and II metabolites) were detected, in some cases in high amounts. These modified forms can be harmful for human health due to their different toxicity, which can be much higher compared to the parent toxin. In addition, the parent toxin can be cleaved from the phase I and II metabolites during digestion. A risk of correlated and additive adverse effects of the metabolites of ZEN phase I and II in humans and animals is evident. ZEN is considered in many studies on its occurrence in grain-based foods and some studies are dedicated to the behavior of ZEN during food processing. This is not the case for the ZEN phase I and II metabolites, which are only included in a few occurrence reports. Their effects during food processing is also only sporadically addressed in studies to date. In addition to the massive lack of data on the occurrence and behavior of ZEN modified forms, there is also a lack of comprehensive clarification of the toxicity of the numerous different ZEN metabolites detected to date. Finally, studies on the fate during digestion of the relevant ZEN metabolites will be important in the future to further clarify their relevance in processed foods such as bakery products.

Draft Genome Sequences of Pseudomonas sp. Strains Isolated from Wheat in Germany.

Three chloramphenicol-resistant Pseudomonas sp. strains were isolated from wheat grain in Germany on rose Bengal agar. The draft genome sizes ranged from 5,924,931 to 6,124,470 bp. All the isolates possessed genes for efflux pumps that might be responsible for an intrinsic chloramphenicol resistance. No acquired antibiotic resistance genes in these strains could be determined.