Mutation breeding of lipase-producing strain Flavobacterium sp. by supercritical CO2 with hydrazine hydrate

This work aimed to obtain an ideal mutant strain with higher lipase yield using hydrazine hydrate (HZH) as a novel additive to treat Flavobacterium sp. strain YY25 by supercritical CO2. The survival rate and the positive mutation rate of the tested strain were strongly dependent on the dose of HZH. The treatment by 0.5% HZH in supercritical CO2 (8 MPa, 35°C) for 30 min provided 58.3% of positive mutation rate and an expected mutant strain with about 76.7% increase in lipase yield compared with the wild strain. Possible mutagenesis mechanisms were further explored. The analysis on pH drop of the treated seed liquid was performed to better understand the interaction. Results proved that the induced mutation with enhanced yield of lipase could be achieved by co-mutagenesis of supercritical CO2 and HZH.

Estrogen-like activity of volatile components from Vitex rotundifolia L.

BACKGROUND & OBJECTIVES: The fruits of Vitex rotundifolia L. are used as a traditional medicine in China. Dried fruits of V. rotundifolia (rich in essential oils) have been known to show strong estrogenic activity. Therefore, we investigated volatile components in the essential oil isolated from the fruits of V. rotundifolia and its estrogen-like biological activity in human breast adenocarcinoma cells. METHODS: Essential oil was extracted by SFE (supercritical fluid extraction) and its chemical composition was analysed by gas chromatography-mass spectrometry (GC-MS). The estrogenic activity of essential oil was evaluated in the MCF-7 cells by proliferation assay. RESULTS: The chemical composition of 40 compounds was determined and this represented 84.1 per cent of the total oil which was characterized by a high content of unsaturated fatty acids (54.84% of total oil). The oil contained mainly linoleic acid (47.46%), palmitic acid (5.18%), untriacontane (2.28%), bicetyl (2.61%) and stearic acid (2.2%). The essential oil strongly stimulated the proliferation of MCF-7 cells, and this effect was significantly inhibited by the specific estrogen receptor antagonist ICI 182,780. INTERPRETATION & CONCLUSION: Our results showed estrogen-like biological activity of the essential oil of the fruits from V. rotundifolia, and in future has a potential medical application.