[Development of PCR rapid detection method for Listeria monocytogenes in oysters].

OBJECTIVE: To develop a polymerase chain reaction(PCR) method for rapid detection of Listeria monocytogenes in oysters without pre-enrichment. METHODS: The combination of ß-cyclodextrin and bentonite-coated activated carbon was used to remove PCR inhibitors from oyster samples, and the target gene inlB was used for the PCR subsequently. The specificity, sensitivity, and application of the developed method were verified, and the stability and application of the reagents stored under cryopreservation conditions were evaluated. RESULTS: The specificity of the developed PCR method was 100% for the detection of 130 target bacterial strains and 63 non-target bacterial strains. The method reduced the time required for Listeria monocytogenes detection to 4 h without pre-enrichment, and the detection limit was 10 CFU/25 g. The method was consistent with the conventional culture method on the detection rate and viable bacteria detection rate of Listeria monocytogenes in natural oyster samples(the coincidence rate was 100%). Additionally, the reagents could be used normally after storing at-20 ℃ for at least one year. CONCLUSION: The PCR method developed in this study has high specificity and sensitivity, and can be used for rapid, accurate detection of Listeria monocytogenes in oysters.

Diversity of soil fungi in the vineyards of Changli region in China.

This study aimed to elucidate the fungal diversity of Changli vineyard soil in China. High-throughput sequencing technology was used to investigate the diversity and composition of soil fungi in five vineyards from different geographical locations in Changli. Although the five vineyards had similar fungal communities, the diversity, composition, and distribution of the high-abundance species differed. Ascomycota, Basidiomycota, and Mortierellomycota were dominant phyla. Among the 14 high-abundance genera of fungi, Odiodendron, Pleotrichocladium, and Plectosephalella have rarely been reported in other vineyards and are unique to the Changli region. In addition, Solicoccozyma aeria and Solicoccozyma terrea were the dominant species in the five vineyards and have rarely been reported in domestic vineyards. Additionally, Rhizophagus, Wardomyces, Mortierella, Volutella, and Cryptococcus were significantly different among the five vineyard soils. Among these species, Mortierella was highly abundant in each vineyard, but its contents were significantly different across vineyards. These findings enrich the information on the composition and diversity of soil fungi in the vineyard of the Changli region, which helps to explore the regional or distinctive sensorial attributes of wine from the perspective of microbial biogeography.

Influence of Phosphorylation and Acetylation on Structural, Physicochemical and Functional Properties of Chestnut Starch.

Chestnut is popular worldwide for its unique flavor, high eating quality and nutrition. Here, we evaluated the influence of phosphorylation and acetylation on the structural, physicochemical and functional properties of chestnut starch. Scanning electron micrographs showed the agglomeration of starch granules and the appearance of numerous dents on the starch granule surface under phosphorylation and acetylation. X-ray diffractograms confirmed that the modification treatments did not affect the C-type crystal pattern, but reduced the relative crystallinity of the chestnut starch, particularly phosphorylation. Moreover, modification improved the paste transparency of the starch. Differential scanning calorimeter analysis revealed that the gelatinization temperature and enthalpy of the starch decreased with the increasing substitution degree, particularly in phosphorylated starch. The Rapid Visco Analyser analysis demonstrated that phosphorylation could greatly improve the pasting properties of chestnut starch. In addition, phosphorylated and acetylated starch had a smaller amount of slowly digested starch and a larger amount of resistant starch relative to native chestnut starch. In conclusion, the functional and physicochemical properties of chestnut starch can be significantly improved through phosphorylation and acetylation, demonstrating its great application potential as a food additive.