Investigation of aflatoxins,mycobiota,and toxigenic fungi during post-harvest handling of Ziziphi Spinosae Semen / 中国中药杂志

Ziziphi Spinosae Semen is one of the Chinese herbal medicine being susceptible to aflatoxins contamination. To investigate the sources of aflatoxins contamination and toxigenic fungi species on Ziziphi Spinosae Semen,32 samples were collected from multiple steps during the post-harvest processing in this study. Aflatoxins in these samples were determined by immunoaffinity column and HPLC coupled with post-column photochemical derivatization. The dilution-plate method was applied to the fungi isolation. The isolated fungi strains were identified by morphological characterization and molecular approaches. The results showed that aflatoxins were detected in 28 samples from every step during the processing of Ziziphi Spinosae Semen. Three samples were detected with aflatoxin B_1 and 2 samples with both aflatoxin B_1 and total aflatoxin exceeding the limit of Chinese Pharmacopoeia. Especially the samples from the washing step,with the highest detected amounts of AFB_1 and AFs were reached 94. 79,121. 43 μg·kg~(-1),respectively. All 32 samples were contaminated by fungi. The fungal counts on the newly harvested samples were 2. 20 × 10~2 CFU·g~(-1). Moreover,it increased as tphreocessing progresses,and achieved 1. 16×10~6 CFU·g~(-1) after washing. A total of 321 isolates were identified to 17 genera. Aspergillus flavus was the main source of aflatoxins during the processing and storage of Ziziphi Spinosae Semen. One isolate of A. flavus was confirmed producing AFB_1 and AFB_2. The fungal count was significantly increased by composting,and Aspergillus was the predominant genus after shell breaking. The contamination level of aflatoxins was increased by composting and washing.

Autotoxic effect of ginsenoside extrats on growth of American ginseng in different medium / 中国中药杂志

Ginsenosides are the abundant secondary metabolites in American ginseng (Panax quinquefolium), it could be released into soil through root exudation and decomposition during plant growth. This study determined ginsenoside contents in American ginseng cultivated soil by HPLC. Three ginsenosides, Rb1, Rb2 and Rd, were detected in the rhizosphere soil of 3-4 years old American ginseng cultivated in Huairou District, Beijing, and their contents were 0.80-3.19 mg x kg(-1). Correspondingly, the contents of the three ginsenosides in soil solution were 4-16 mg x L(-1) at field water-holding capacity of 20%. According to the field soil test data, we designed the concentration of ginsenosides for bioassays (0.2-125 mg x L(-1) in solution or 0.2-125 mg x kg(-1) in soil). The results showed that radicle lengths of American ginseng were reduced by 6%-23% in solution containing 0.2-125 mg x L(-1) ginsenoside extract, and a significant difference was observed at concentration of 125 mg x L(-1) (P < 0.05). The shoot lengths of American ginseng were not significantly inhibited by 0.2-125 mg x L(-1) ginsenosides extractions. After 20 days of growth in nutrient solution amended with 25 mg x L(-1) ginsenosides extraction, plant height of 3-year-old American ginseng seedling was decreased by 28% compared to the control, and the biomass of aerial parts was also reduced by 50% (P < 0.05). However, the growth of newly-grown fibrous root was not significantly inhibited. Comparatively, when American ginseng embryos were cultivated into sterile or non-sterile soil, neither radicle lengths nor shoot lengths were significantly affected by 0.2-125 mg x kg(-1) ginsenoside extracts. In conclusion, ginsenosides showed autotoxic effect on growth of American ginseng radicle and adult seedling, however, this effect was weakened in field soil.

Fungal composition in massa medicata fermentata based on culture dependent method and independent PCR-SSCP technique / 中国中药杂志

<p><b>OBJECTIVE</b>To analyze the fungal composition in Massa Medicata Fermentata based on culture dependent method and independent PCR-SSCP technique.</p><p><b>METHOD</b>Fungi were directly isolated from Massa Medicata Fermentata samples. The obtained strains were identified according to morphology and DNA sequence. Meanwhile the total fungal DNA was extracted from Massa Medicata Fermentata samples, the cultural independent PCR-SSCP technique based on β-tubulin gene were used to identify the mycobiota.</p><p><b>RESULT</b>According to cultural method, Aspergillus flavus and Rhizopus oryzae were present in Massa Medicata Fermentata samples, while A. flavus and A. niger were present in fried Massa Medicata Fermentata samples. In contrast, 5 species were obtained by PCR-SSCP technique, A. flavus was overlapped with fungal taxa derived from culture dependent method; A. ambiguu and A. s ivoriensis were dominant with relative abundance of 57% and 35% respectively, while the relative abundance of A. flavus was as low as 4%. None species was obtained from fried Massa Medicata Fermentata samples.</p><p><b>CONCLUSION</b>PCR-SSCP based on β-tubulin gene could distinguish fungi into species, culture dependent method combined with culture independent method could better understand the fungal composition associated with Massa Medicata Fermentata fermentation.</p>

Effect of continuous cropping and soil treatment on rhizosphere fungal community of Panax quinquefolium / 中国中药杂志

<p><b>OBJECTIVE</b>To analyze the effects of continuous cropping and soil treatment on rhizosphere fungal community of Panax quinquefolium, and the correlation between rhizosphere fungal community and growth of P. quinquefolium.</p><p><b>METHOD</b>Field plot trail of continuous cultivated P. quinquefolium was conducted, meanwhile continuous cropping soil was treated by organic carbon fertilizer plus methylene dithiocyanate and Kingbo respectively. The rate of seedling survival, root disease index and root weight were investigated. Dilution plating was used to analyze the rhizosphere fungal community, multiple comparisons including H, M(a) and J were performed between rhizosphere fungal community and growth of P. quinquefolium.</p><p><b>RESULT</b>As to P. quinquefolium planted in continuous soil, the rate of seedling survival, root weight decreased, root disease index increased remarkably (P<0.05). Meanwhile the fungal counts decreased 50% -63% , the diversity index (H') decreased 39%-43%, while the ratio of Penicillium and Aspergillus increased. There was a significant negative correlation between rhizosphere fungal diversity and P. quinquefolium root disease index (r = -0.970, P=0.006). Organic carbon fertilizer plus methylene dithiocyanate treatment could improve the rate of seedling survival and root weight, and could partly increase the rhizosphere fungal diversity.</p><p><b>CONCLUSION</b>In continuous cropping soil of P. quinquefolium, the rhizosphere fungal counts and diversity index decreased, meanwhile the fungal community composition changed. Organic carbon fertilizer plus methylene dithiocyanate treatment could improve the growth of continuous cultivated P. quinquefolium.</p>

Variation of ginsenosides in infected roots of American ginseng (Panax quinquefolium) / 中国中药杂志

<p><b>UNLABELLED</b>To study the infected root of Panax quinquefolium on the contents of ginsenosides.</p><p><b>METHOD</b>The contents of three major ginsenosides Rg1, Re and Rb1 were determined by HPLC compared quantitatively between the different degree infected roots and normal root in the phloem and xylem.</p><p><b>RESULT</b>Rg1 in phloem and xylem of varying degrees infected root showed no significant difference, but Rb1 decreased 26.3% and 28.3% respectively in medium and serious infected roots comparing to normal root. Re in phloem of seriously infected roots decreased in xylem significantly.</p><p><b>CONCLUSION</b>The results indicate that the variation of ginsenosides in different degrees infected roots exists and the proportion of Rg1, Re and Rb1 in the total ginsenosides changes.</p>