Rice false smut is an emerging and economically-important rice disease caused by infection by the fungal pathogen Villosiclava virens. Ustiloxin B is an antimitotic cyclopeptide mycotoxin isolated from the rice false smut balls that formed in the pathogen-infected rice spikelets. A monoclonal antibody (mAb) designated as mAb 1B5A10 was generated with ustiloxin B—ovalbumin conjugate. A highly-sensitive and specific indirect competitive enzyme-linked immunosorbent assay (icELISA) was then developed. The median inhibitory concentration (IC50) of the icELISA was 18.0 ng/mL for the detection of ustiloxin B; the limit of detection was 0.6 ng/mL, and the calibration range was from 2.5 to 107.4 ng/mL. The LOD/LOQ values of the developed ELISA used for the determination of ustiloxin B in rice false smut balls and rice grains were 12/50 μg/g and 30/125 ng/g, respectively. The mAb 1B5A10 cross-reacted with ustiloxin A at 13.9% relative to ustiloxin B. Average recoveries of ustiloxin B ranged from 91.3% to 105.1% for rice false smut balls at spiking levels of 0.2 to 3.2 mg/g and from 92.6% to 103.5% for rice grains at spiking levels of 100 to 5000 ng/g. Comparison of ustiloxin B content in rice false smut balls and rice grains detected by both icELISA and high performance liquid chromatography (HPLC) demonstrated that the developed icELISA can be employed as an effective and accurate method for the detection of ustiloxin B in rice false smut balls, as well as rice food and feed samples.

Background Dulong (Drung people) are one of the ethnic minorities of China, consisting of a small population living in remote and mountainous regions with limited facilities. Over the years, the Dulong have maintained their livelihood by collecting wild medicinal and edible plants. Therefore, through their experience and understanding, they had accumulated sufficient traditional knowledge about local plant resources. Since ancient times, wild edible plants have been essential to the food security of the Dulong people. However, there is almost no comprehensive report available on WEPs consumed by the Dulong people. The objectives of this study were to: (1) make a systematic study of WEPs used by Dulong people, (2) record traditional knowledge related to WEPs, (3) analyze multiple uses of WEPs, and (4) evaluate species with significant cultural significance to Dulong people. Methods Ethnobotanical survey including free listing, semi-structured interviews, key informant interviews and participatory observations was conducted in Dulongjiang Township, Gongshan County, Yunnan Province, Southwest China. A total of 127 informants were selected using the snowball method and information about WEPs, including vernacular name, food categories, parts used, mode of consumption, collection season, and other local uses were collected. The RFC and CFSI were calculated to identify the most culturally significant WEPs. One-way analysis of variance was performed to evaluate whether the four reference variables (gender, age, occupation, and education) significantly influenced the number of plant species mentioned by the respondents. Results and discussion A total of 148 species of WEPs consumed by the Dulong people belonging to 58 families were collected, including wild vegetables (71), wild fruits (52), staple food substitutes (15), spices (7), nuts (4), tea substitute (2), liquor making materials (3) oils and fats (3), and culinary coagulants (1). WEPs are used in a number of different ways, including as fuelwood, feed, and medicine. Food substitute plants accounted for the majority of the top 27 wild food plants identified by RFC and CFSI. It was observed that farmers have more knowledge of WEPs, and moderate education level informants reported less WEPs used. Conclusion The WEPs used by the Dulong people are diverse and abundant in the Dulongjiang region. In the future, WEPs such as Maianthemum atropurpureum, Caryota obtusa, Cardiocrinum giganteum, and Angiopteris esculenta with economic potential can be developed to provide a source of income for the residents. More studies of the nutritional value, chemical composition, and biological activities of WEPs are needed. The demands and development of local communities can be realized under the premise of protecting WEPs and the associated traditional knowledge. More attention should be paid to the value of WEP and underutilized plants during future rural development.

Fermented foods have unique microbiota and metabolomic profiles that can support dietary diversity, digestion, and gut health of consumers. Laowo ham (LWH) is an example of an indigenous fermented food from Southwestern China that has cultural, ecological, economic, and health significance to local communities. We carried out ethnobiological surveys coupled with metagenomic and metabolomic analyses using GC-TOF-MS and UPLC-QTOF-MS to elucidate the microbiota and metabolic profiles of LWH samples at different ripening stages. The results from high-throughput sequencing showed a total of 502 bacterial genera in LWH samples with 12 genera of bacteria and 6 genera of fungi identified as dominant groups. This is the first study to our knowledge to report the bacteria of Lentibacillus and Mesorhizobium along with fungi Eremascus and Xerochrysium on a fermented meat product. Findings further revealed that the metabolite profiles among LWH samples were significantly different. In total, 27 and 30 metabolites from GC-TOF-MS and UPLC-QTOF-MS analysis, respectively, were annotated as highly discriminative metabolites. Among the differential compounds, the relative contents of most amino acids showed the highest in the LWH sample ripened for two years, while some metabolites with potential therapeutic effects such as levetiracetam were the most abundant in the LWH sample ripened for three years. The correlation analysis indicated that the dominant microbes were closely related to differential metabolites, highlighting the importance of their functional characterization. Findings indicate that the consumption of LWH contributes to microbiological and chemical diversity of human diets as well as suggests efficacy of combining GC-MS and LC-MS to study the metabolites in dry-cured meat products.

Ustiloxins are cyclopeptide mycotoxins isolated from rice false smut balls (FSBs), the ball-like colonies transformed from the individual grains through the filament infection by the fungal pathogen Villosiclava virens. There were no obvious relations between ustiloxin content and any of the collection areas, collection times, or average weight of each FSB. The rice false smut balls at early, middle, and late maturity stages were respectively divided into different parts (glume, chlamydospores, mycelia, and pseudoparenchyma). The highest content of ustiloxins A and B of rice FSBs was found at the early maturity stage. Both ustiloxins A and B were mainly distributed in the middle layer containing mycelia and immature chlamydospores of the FSBs. When the rice FSBs were at the early maturity stage, the total yield of ustiloxins A and B in the middle layer of each ball was 48.3 µg, which was 3.20-fold of the yield (15.1 µg) of the inner part of the ball. The rice FSBs at the early maturity stage are the appropriate materials for the production of ustiloxins A and B.