Storage Fungi and Mycotoxins Associated with Rice Samples Commercialized in Thailand

The study focused on the examination of the different fungal species isolated from commercial rice samples, applying conventional culture techniques, as well as different molecular and phylogenic analyses to confirm phenotypic identification. Additionally, the mycotoxin production and contamination were analyzed using validated liquid chromatography-tandem mass spectrometry (LC-MS/MS). In total, 40 rice samples were obtained covering rice berry, red jasmine rice, brown rice, germinated brown rice, and white rice. The blotting paper technique applied on the 5 different types of rice samples detected 4285 seed-borne fungal infections (26.8%) for 16,000 rice grains. Gross morphological data revealed that 19 fungal isolates belonged to the genera Penicillium/Talaromyces (18 of 90 isolates; 20%) and Aspergillus (72 of 90 isolates; 80%). To check their morphologies, molecular data (fungal sequence-based BLAST results and a phylogenetic tree of the combined ITS, BenA, CaM, and RPB2 datasets) confirmed the initial classification. The phylogenic analysis revealed that eight isolates belonged to P. citrinum and, additionally, one isolate each belonged to P. chermesinum, A. niger, A. fumigatus, and A. tubingensis. Furthermore, four isolates of T. pinophilus and one isolate of each taxon were identified as Talaromyces ( T. radicus, T. purpureogenum, and T. islandicus). The results showed that A. niger and T. pinophilus were two commonly occurring fungal species in rice samples. After subculturing, ochratoxin A (OTA), generated by T. pinophilus code W3-04, was discovered using LC-MS/MS. In addition, the Fusarium toxin beauvericin was detected in one of the samples. Aflatoxin B1 or other mycotoxins, such as citrinin, trichothecenes, and fumonisins, were detected. These preliminary findings should provide valuable guidance for hazard analysis critical control point concepts used by commercial food suppliers, including the analysis of multiple mycotoxins. Based on the current findings, mycotoxin analyses should focus on A. niger toxins, including OTA and metabolites of T. pinophilus (recently considered a producer of emerging mycotoxins) to exclude health hazards related to the traditionally high consumption of rice by Thai people

Genetic Variation of Coleosporium plumeriae from Different Provinces in Thailand

Plumeria rust samples were collected from five provinces in Thailand, including Bangkok, Nakhon Pathom, Rayong, Chonburi and Yala. All five isolates produced the uredial stage but only the isolates from Bangkok and Yala also underwent the telial and basidial stages. The morphological characteristics of all three stages present in the life cycle of the isolates were studied under stereo, compound and electron microscopes. Ribosomal DNA (rDNA) sequences at 28S and ITS (internal transcribed spacer) regions were analyzed with those in the GenBank database by Nucleotide BLAST and phylogenetic analyses. Coleosporium plumeriae was identified as the causal agent of plumeria rust by structure morphology and rDNA sequences that revealed genetic variation of the fungus as well. In general, there were significant differences in the morphological characteristics of uredospores, teliospores and basidia among the isolates. However, the variation of spore morphology was not related to the sampling locations. According to the phylogenetic analysis of 28S rDNA sequences, the UPGMA tree grouped all C. plumeriae from Thailand and foreign countries in the same clade as they shared identical sequences. On the other hand, the UPGMA tree inferred from ITS rDNA sequence data detected genetic variation of the isolate from Chonburi and separated it into the distinct tree branch. In this study, structure morphology and ITS rDNA were suitable genetic markers for both interspecific and intraspecific taxonomy of C. plumeriae

Occurrence and health risk of patulin and pyrethroids in fruit juices consumed in Bangkok, Thailand

The mycotoxin patulin (PAT) is well known as a natural contaminant of apple- and other fruit-based products. Pesticides are a group of chemicals abundantly used in agriculture to maximize productivity by protecting crops from pests and weeds. Because of their harmful health effects, PAT and pesticides are strictly monitored. The current study was undertaken to investigate the significance of PAT and pyrethroid insecticide contamination in a variety of fruit juices in Bangkok. To do this, a total of 200 fruit juice samples, consisting of 40 samples each of apple, apricot, peach, pineapple, and grape juice, were collected from supermarkets in Bangkok, Thailand. PAT contamination in a variety of fruit juices was detected using validated liquid chromatography-tandem mass spectrometry, and pyrethroid insecticides (cypermethrin, cyfluthrin, and flumethrin) were analyzed using a gas chromatography equipped with micro-electron capture detector. The survey found that PAT concentrations were lower than the maximum residue limit established by European Union. The results of the present study suggest that the risk of exposure to harmful levels of PAT, cypermethrin, cyfluthrin, and flumethrin in fruit juices is very low in urban areas of Thailand