Isolation and Molecular Identification of the Native Microflora on Flammulina velutipes Fruiting Bodies and Modeling the Growth of Dominant Microbiota (Lactococcus lactis)

Isolation and Identification of Acer truncatum Endophytic Fungus Talaromyces verruculosus and Evaluation of Its Effects on Insoluble Phosphorus Absorption Capacity and Growth of Cucumber Seedlings

The symbiosis between endophytic fungi and plants can promote the absorption of potassium, nitrogen, phosphorus, and other nutrients by plants. Phosphorus is one of the indispensable nutrient elements for plant growth and development. However, the content of available phosphorus in soil is very low, which limits the growth of plants. Phosphorus-soluble microorganisms can improve the utilization rate of insoluble phosphorus. In this study, Talaromyces verruculosus (T. verruculosus), a potential phosphorus-soluble fungus, was isolated from Acer truncatum, a plant with strong stress resistance, and its phosphorus-soluble ability in relation to cucumber seedlings under different treatment conditions was determined. In addition, the morphological, physiological, and biochemical indexes of the cucumber seedlings were assessed. The results show that T. verruculosus could solubilize tricalcium phosphate (TCP) and lecithin, and the solubilization effect of lecithin was higher than that of TCP. After the application of T. verruclosus, the leaf photosynthetic index increased significantly. The photosynthetic system damage caused by low phosphorus stress was alleviated, and the root morphological indexes of cucumber seedlings were increased. The plant height, stem diameter, and leaf area of cucumber seedlings treated with T. verruculosus were also significantly higher than those without treatment. Therefore, it was shown that T. verruculosus is a beneficial endophytic fungus that can promote plant growth and improve plant stress resistance. This study will provide a useful reference for further research on endophytic fungi to promote growth and improve plant stress resistance.

Multi-omics reveals the protective effects of curcumin against AFB1-induced oxidative stress and inflammatory damage in duckling intestines

Aflatoxin B1 (AFB1) is the most prevalent and toxic class of aflatoxins, which is considered a significant risk factor for food safety. Curcumin, a phytoconstituent with anti-inflammatory and antioxidant properties, has potential therapeutic value for intestinal inflammatory diseases. In this study, the duckling model susceptible to AFB1 was selected for toxicity testing, aiming to explore the effect of curcumin on AFB1 enterotoxicity and its possible mechanism of action. The results showed that curcumin promoted the growth and development of ducklings and mitigated the changes in morphology and permeability serological index (DAO and D-LA) after AFB1 exposure. Curcumin also mitigated AFB1-induced oxidative stress by activating the Nrf2 pathway, and ameliorated intestinal inflammation by inhibiting the NF-κB/IκB signaling pathway and boosting intestinal autophagy. In terms of gut flora and their metabolites, we found that curcumin supplementation significantly increased the intestinal flora's abundance index and diversity index compared to the AFB1 group, mitigating the decline in the abundance of Actinobacteria and the rise in that of harmful bacteria Clostridia. Furthermore, untargeted metabolomic analysis revealed that the protective effect of curcumin on the intestine was mainly through the regulation of AFB1-induced disorders of lipid metabolism, involving linoleic acid metabolism, α-linolenic acid metabolism, and glycerolipid metabolism. Overall, the enteroprotective effects of curcumin may be of significant value in the future for treating chronic AFB1 poisoning and also provide new therapeutic ideas for other mycotoxicosis.

Comparative Study of ɛ-Polylysine or Nisin Inhibition Kinetics of Lactococcus lactis and Spoilage Microorganisms in Fresh Flammulina velutipes Fruiting Bodies

Flammulina velutipes is one of the most important edible mushrooms, which quickly decays with a short shelf life. However, little is known about the effect of ɛ-polylysine (ɛ-PL) or nisin on the survival of Lactococcus lactis (L. lactis) during the storage at constant temperatures. The objective of this study was to investigate the effect of ɛ-PL or nisin on the growth of L. lactis and background (BK) microorganisms in fresh Flammulina velutipes fruiting bodies (FVFB) and develop mathematical models to predict their growth behavior. The effect of ɛ-PL (0.15 and 0.30 g/kg) or nisin (0.10 and 0.20 g/kg) on the growth of L. lactis and BK microorganisms in FVFB was analyzed at 4, 16, and 20°C. The lag phase of L. lactis was extended, and the specific growth rate was decreased by increasing concentrations of ɛ-PL or nisin and lowering the temperature. The results showed that ɛ-PL or nisin could control the growth of L. lactis in FVFB. However, the growth of BK microorganisms was not affected by ɛ-PL or nisin. The growth of L. lactis and BK microorganisms could be successfully described by the reparameterized Gompertz and no lag phase models, respectively. Additionally, ɛ-PL or nisin could maintain the quality of FVFB by preventing weight loss, color-changing, and decreasing soluble solid content in FVFB at 4°C. These results suggest that ɛ-PL or nisin in combination with low temperature may inhibit the growth of L. lactis in FVFB and prevent the decrease in the quality of FVFB.