Identification and partial purification of thuricin 4AJ1 produced by Bacillus thuringiensis.

Thuricin 4AJ1, produced by Bacillus thuringiensis strain 4AJ1, showed inhibition activity against Bacillus cereus 0938 and ATCC 10987. It began to appear in the stationary phase and reached its maximum activity level of 209.958 U at 18 h against B. cereus 0938 and 285.689 U at 24 h against B. cereus ATCC 10987. Tricine-SDS-PAGE results showed that the partly purified thuricin 4AJ1 was about 6.5 kDa. The molecular weights of the known B. thuringiensis bacteriocins and the ones obtained by the two mainstream websites for predicting bacteriocins were inconsistent with the size of the thuricin 4AJ1, indicating that the bacteriocin obtained in this study may have a novel structure. Based on the biochemical properties, the thuricin 4AJ1 activities increased after treatment with proteinase K and lipase II, and were not affected by a-amylase, catalase, α-chymotrypsin VII and α-chymotrypsin II. It was heat tolerant, being active up to 90º C. In the pH 3-10 range, it maintained most of its activity. Finally, the sensitivity of the strain 4AJ1 to commonly used antibiotics was tested. In view of its stability and antibacterial activity, thuricin 4AJ1 may be applied as a food biopreservative.

[Diversity of Endogeny Eumycetes in Gynostemma pentaphyllum and Its Correlation with Gypenoside XLIX].

OBJECTIVE: To study the correlation between active components and endogeny eumycetes in Gynostemma pentaphyllum of different types from different habitats. METHODS: Endogeny eumycetes from different parts of Gynostemma pentaphyllum were isolated by general isolation methods. Insert method and point planting method were used for identification. The content of gypenoside XLIX were determined by HPLC. RESULTS: 125 endogeny eumycetes inhabiting in Gynostemma pentaphyllum were isolated from roots, rhizomes and leaves. By colony morphology and microscopic characteristics, 22 genera from 10 families, 7 orders, 2 classes were identified. Fusarium was the most abundant endogeny eumycetes in Gynostemma pentaphyllum with the account of 22. 4%. Penicillium and Leptosphaeria was 12. 8% and 9. 6% respectively. The correlation between Gypenoside XLIX and endogeny eumycetes in Gynostemma pentaphyllum was revealed. CONCLUSION: Endogeny eumycetes are diverse in species and quantity. The endogeny eumycetes species is related to the quality of Gynostemma pentaphyllum.