Occurrence of Penicillium brocae and Penicillium citreonigrum, which Produce a Mutagenic Metabolite and a Mycotoxin Citreoviridin, Respectively, in Selected Commercially Available Rice Grains in Thailand

Promotion of Tricholoma matsutake mycelium growth by Penicillium citreonigrum

Tricholoma matsutake has been the most valuable ectomycorrhizal fungi in Asia because of its unique flavor and taste. However, due to the difficulty of artificial cultivation, the cultivation of T. matsutake has relied on natural growth in forests. To cultivate the T. matsutake artificially, microorganisms in fairy rings were introduced. In this study, we isolated 30 fungal species of microfungi from the soil of fairy rings. Among them, one single fungal strain showed a promoting effect on the growth of T. matsutake. The growth effect was confirmed by measuring the growth area of T. matsutake and enzyme activities including α-amylase, cellulase, and β-glucosidase. In comparison with control, microfungal metabolite increased the growth area of T. matsutake by 213% and the enzyme activity of T. matsutake by 110-200%. The isolated fungal strain was identified as Penicillium citreonigrum by BLAST on the NCBI database. The Discovery of this microfungal strain is expected to contribute to artificial cultivation of T. matsutake.

T-DNA insertion mutagenesis in Penicillium brocae results in identification of an enolase gene mutant impaired in secretion of organic acids and phosphate solubilization

Penicillium brocae strain P6 is a phosphate-solubilizing fungus isolated from farmland in Guangdong Province, China. To gain better insights into the phosphate solubilization mechanisms of strain P6, a T-DNA insertion population containing approximately 4500 transformants was generated by Agrobacterium tumefaciens-mediated transformation. The transformation procedure was optimized by using a Hybond N membrane for co-cultivation of A. tumefaciens and P. brocae. A mutant impaired in phosphate solubilization (named MT27) was obtained from the T-DNA insertion population. Thermal asymmetric interlaced PCR was then used to identify the nucleotide sequences flanking the T-DNA insertion site. The T-DNA in MT27 was inserted into the fourth exon of an enolase gene, which shows 90.8 % nucleotide identity with enolase mRNA from Aspergillus neoniger. Amino acid sequence homology analysis indicated that the enolase is well conserved among filamentous fungi and Saccharomyces cerevisiae. Complementation tests with the MT27 mutant confirmed that the enolase gene is involved in phosphate solubilization. Analysis of organic acids in culture supernatants indicated reduced levels of oxalic acid and lactic acid for the MT27 mutant compared to the parent strain P6 or the complementation strain. In conclusion, we suggest that the identified enolase gene of P. brocae is involved in production of specific organic acids, which, when secreted, act as phosphate solubilizing agents.

Fungal Catastrophe of a Specimen Room: Just One Week is Enough to Eradicate Traces of Thousands of Animals

Indoor fungi obtain carbon sources from natural sources and even recalcitrant biodegradable materials, such as plastics and synthetic dye. Their vigorous activity may have negative consequences, such as structural damage to building materials or the destruction of precious cultural materials. The animal specimen room of the Seoul National University stocked 36,000 animal resources that had been well-maintained for over 80 years. Due to abandonment without the management of temperature and humidity during the rainy summer season, many stuffed animal specimens had been heavily colonized by fungi. To investigate the fungal species responsible for the destruction of the historical specimens, we isolated fungi from the stuffed animal specimens and identified them at the species level based on morphology and molecular analysis of the β-tubulin (BenA) gene. A total of 365 strains were isolated and identified as 26 species in Aspergillus (10 spp.), Penicillium (14 spp.), and Talaromyces (2 spp.). Penicillium brocae and Aspergillus sydowii were isolated from most sections of the animal specimens and have damaged the feathers and beaks of valuable specimens. Our findings indicate that within a week of mismanagement, it takes only a few fungal species to wipe out the decades of history of animal diversity. The important lesson here is to prevent this catastrophe from occurring again through a continued interest, not to put all previous efforts to waste.

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.

The importance and mitigation of mycotoxins and plant toxins in Southeast Asian fermented foods

Fermented foods (ffs) and beverages are widely consumed in Southeast Asia (SEA) for their nutritional balance, flavor, and food security. They serve as vehicles for beneficial microorganisms performing a significant role in human health. However, there are still major challenges concerning the safety of ffs and beverages due to the presence of natural toxins. In this review, the common toxins found in traditional ffs in SEA are discussed with special reference to mycotoxins and plant toxins. Also, mitigation measures for preventing risks associated with their consumption are outlined. Ochratoxin, citrinin, aflatoxins were reported to be major mycotoxins present in SEA ffs. In addition, soybean-based ff food products were more vulnerable to mycotoxin contaminations. Common plant toxins recorded in ffs include cyanogenic glycosides, oxalates, phytates and saponins. Combined management strategies such as pre-harvest, harvest and post-harvest control and decontamination, through the integration of different control methods such as the use of clean seeds, biological control methods, fermentation, appropriate packaging systems, and controlled processing conditions are needed for the safe consumption of indigenous ffs in SEA.

Gut Microbial Alterations in Diarrheal Baer's Pochards (Aythya baeri)

The structure and composition of gut microbiota correlate with the occurrence and development of host health and disease. Diarrhea can cause alterations in gut microbiota in animals, and the changes in the gut microbial structure and composition may affect the development of diarrhea. However, there is a scarcity of information on the effects of diarrhea on gut fungal composition and structure, particularly in Baer's pochard (Aythya baeri). The current study was performed for high-throughput sequencing of the fungal-specific internal transcribed spacer 1 (ITS-1) to detect the differences of gut mycobiota in healthy and diarrheal Baer's pochard. Results showed that the gut mycobiota not only decreased significantly in diversity but also in structure and composition. Statistical analysis between two groups revealed a significant decrease in the abundance of phylum Rozellomycota, Zoopagomycota, Mortierellomycota, and Kickxellomycota in diarrheal Baer's pochard. At the genus levels, fungal relative abundance changed significantly in 95 genera, with 56 fungal genera, such as Wickerhamomyces, Alternaria, Penicillium, Cystofilobasidium, and Filobasidium, increasing significantly in the gut of the diarrheal Baer's pochard. In conclusion, the current study revealed the discrepancy in the gut fungal diversity and community composition between the healthy and diarrheal Baer's pochard, laying the basis for elucidating the relationship between diarrhea and the gut mycobiota in Baer's pochard.

Penicillium spp. mycotoxins found in food and feed and their health effects

Mycotoxins are toxic secondary metabolites produced by fungi. These compounds have different structures and target different organs, acting at different steps of biological processes inside the cell. Around 32 mycotoxins have been identified in fungal Penicillium spp. isolated from food and feed. Some of these species are important pathogens which contaminate food, such as maize, cereals, soybeans, sorghum, peanuts, among others. These microorganisms can be present in different steps of the food production process, such as plant growth, harvest, drying, elaboration, transport, and packaging. Although some Penicillium spp. are pathogens, some of them are used in elaboration of processed foods, such as cheese and sausages. This review summarises the Penicillium spp. mycotoxin toxicity, focusing mainly on the subgenus Penicillium, frequently found in food and feed. Toxicity is reviewed both in animal models and cultured cells. Finally, some aspects of their regulations are discussed.

Zearalenone Mycotoxicosis: Pathophysiology and Immunotoxicity

Mycotoxicosis refers to the deleterious pathological effects of different types of toxins produced by some worldwide distributing fungi. Mycotoxins, as secondary metabolites are affecting different organs and systems both in animals and human beings. Zearalenone (ZEA), the well-known estrogenic mycotoxins, is an immunotoxic agent. This macrocyclic beta-resorcyclic acid lactone is mycotoxin procreated as a secondary metabolic byproduct by several types of Fusarium, encompassing Fusarium roseum, Fusarium culmorum, Fusarium graminearum, and different other types. Attributing to its potent estrogenic activity, ZEA has been incriminated as one of the major causes of female reproductive disorders. Thus, the purpose of the present review article is to appraise the pathophysiological consequences and subsequent explore the progress in the research field of zearalenone immunotoxicities.

Whole Genome Analysis Revealed the Genes Responsible for Citreoviridin Biosynthesis in Penicillium citreonigrum

Citreoviridin (CTV) is a mycotoxin that is produced by Aspergillus terreus, Eupenicillium ochrosalmoneum and Penicillium citreonigrum, and CTV has been detected in a wide range of cereal grains throughout the world. Furthermore, it is especially a serious problem in regions where rice is consumed as a staple food. Moreover, CTV is a well-known yellow rice toxin, and outbreaks of beriberi have occurred due to consumption of rice that is contaminated by CTV even in the recent years. Although CTV biosynthetic genes of A. terreus have been described, those of P. citreonigrum remain unclear, which is concerning since P. citreonigrum is the main cause of CTV contamination in rice. In the present study, we determined the draft genome of the P. citreonigrum strain IMI92228 and revealed the presence of all four genes that form a gene cluster and that are homologous to the CTV biosynthesis genes of A. terreus. The expression of these four homologous genes were highly correlated with CTV production, suggesting that they may play an important role in CTV biosynthesis in P. citreonigrum. We concluded that the gene cluster is a CTV biosynthesis cluster of P. citreonigrum. The findings will contribute to the understanding of the biosynthetic pathway of CTV and will ultimately lead to improvements in the CTV management of agricultural products.

The In Vivo and In Vitro Toxicokinetics of Citreoviridin Extracted from Penicillium citreonigrum

Citreoviridin (CTVD), a mycotoxin called yellow rice toxin, is reported to be related to acute cardiac beriberi; however, its toxicokinetics remain unclear. The present study elucidated the toxicokinetics through in vivo experiments in swine and predicted the human toxicokinetics by comparing the findings to those from in vitro experiments. In vivo experiments revealed the high bioavailability of CTVD (116.4%) in swine. An intestinal permeability study using Caco-2 cells to estimate the toxicokinetics in humans showed that CTVD has a high permeability coefficient. When CTVD was incubated with hepatic S9 fraction from swine and humans, hydroxylation and methylation, desaturation, and dihydroxylation derivatives were produced as the predominant metabolites. The levels of these products produced using human S9 were higher than those obtained swine S9, while CTVD glucuronide was produced slowly in human S9 in comparison to swine S9. Furthermore, the elimination of CTVD by human S9 was significantly more rapid in comparison to that by swine S9. These results suggest that CTVD is easily absorbed in swine and that it remains in the body where it is slowly metabolized. In contrast, the absorption of CTVD in humans would be the same as that in swine, although its elimination would be faster.