Anti-fungal activity of Citrus reticulata Blanco essential oil against Penicillium italicum and Penicillium digitatum.

The chemical composition of Citrus reticulata Blanco essential oil was analysed using GC/MS. Monoterpene hydrocarbons (C10H16) constituted the majority (88.96%, w/w) of the total oil. The oils dose-dependently inhibited Penicillium italicum and Penicillium digitatum. The anti-fungal activity of the oils against P. italicum was attributed to citronellol, octanal, citral, decanal, nonanal, ß-pinene, linalool, and γ-terpinene, whereas anti-fungal activity against P. digitatum is attributed to octanal, decanal, nonanal, limonene, citral, γ-terpinene, linalool, and α-terpineol. The oils altered the hyphal morphology of P. italicum and P. digitatum by causing loss of cytoplasm and distortion of the mycelia. The oils significantly altered extracellular conductivity, the release of cell constituents, and the total lipid content of P. italicum and P. digitatum. The results suggest that C. reticulata Blanco essential oils generate cytotoxicity in P. italicum and P. digitatum by disrupting cell membrane integrity and causing the leakage of cell components.

Efficiency assessment and pH effect in removing nitrogen and phosphorus by algae-bacteria combined system of Chlorella vulgaris and Bacillus licheniformis.

To achieve better removal of NH4(+) and TP in wastewater, a new algae-bacteria combined system of Chlorella vulgaris and Bacillus licheniformis was investigated in a 6-d experiment. The results showed that 78% of NH4(+) could be removed in the combined system, while 29% in single algae system and only 1% in single bacteria system. Approximately 92% of TP was removed in the combined system, compared with 55% and 78% in single algae and bacteria system, respectively. B. licheniformis was proven to be a growth-promoting bacterium for C. vulgaris by comparing Chl a concentrations in the single and combined systems. In the removal process, pH of the combined system was observed to reduce significantly from 7.0 to 3.5. Whereas with pH regulated to 7.0, higher removal efficiencies of NH4(+) (86%) and TP (93%) were achieved along with the recovery of algal cells and the increase of Chl a. These results suggest that nutrients in wastewater can be removed efficiently by the algae-bacteria combined system and pH control is crucial in the process.

Antioxidant efficacy of extracts produced from pickled and dried mustard in rapeseed and peanut oils.

UNLABELLED: Antioxidant efficacy of 70% ethanol extract (EE), 70% methanol extract (ME), and water extract (WE) produced from pickled and dried mustard (Brassica juncea Coss. var. foliosa Bailey) was evaluated in rapeseed and peanut oils by using the Schaal oven method. The protective effects of aforesaid 3 extracts in stabilizing vegetable oils were tested by measuring their peroxide values, conjugated diene values, and p-anisidine values during storage of 15 d at 60 °C. Results showed that the different solvent extracts produced from pickled and dried mustard, at concentrations of 0.5% and 1.0% (w/w) in vegetable oils, could significantly (P < 0.05) lower the peroxide value, conjugated diene value, and p-anisidine value of oils during storage at 60 °C. However, the extracts at various concentrations showed a less antioxidant effect than butylated hydroxytoluene (BHT) at 200 ppm. The ultraviolet spectra of different extracts exhibited a single maximum absorbance at 268 nm. The qualitative analysis of antioxidants present in the extracts was carried out by reverse phase high performance liquid chromatography (HPLC) using a C18 column. Two phenolic compounds, gallic and protocatechuric acids, were identified. The antioxidant activity of the extracts might be attributed to the presence of these phenolics. These results indicated that the pickled and dried mustard could be used as a potential source of natural antioxidants. PRACTICAL APPLICATION: The antioxidant activity of extracts produced from pickled and dried mustard toward rapeseed and peanut oils oxidation and the characterization of active phenolic compounds may be useful in developing natural antioxidants for vegetable oils. Moreover, the extracts could safely be used as potential antioxidant to suppress lipid oxidation in lipid-containing food products.

Functional characterization of Citrus PSY gene in Hongkong kumquat (Fortunella hindsii Swingle).

Citrus, rich in carotenoids, is the most important fruit crop based on the total annual production. In the carotenoid biosynthesis pathway, phytoene synthase (PSY, EC 2.5.1.32) catalyzes the dimerization of two molecules of geranylgeranyl pyrophosphate (GGPP) to phytoene and has been shown to be a rate-limiting enzyme for the synthesis of carotenoids. In this study, we investigated catalytic activity of CsPSY from Cara Cara navel orange (Citrus sinensis Osbeck) by heterologous expression in Escherichia coli containing a GGPP-producing plasmid. Moreover, the effects of CsPSY overexpression on carotenoid accumulation were also functionally analyzed in transgenic Hongkong kumquat (Fortunella hindsii Swingle). The resulting transgenic plants produced orange fruits, and extracts from the fruits of four overexpressing plants had a 2.5-fold average increase of phytoene with the content approximately 71.38 microg/g fresh weight. Lycopene, beta-carotene, and beta-cryptoxanthin in transgenic fruits were also markedly increased, whereas the levels of lutein and violaxanthin kept nearly unchanged with 1.1-1.3 folds variation. Transcript levels of carotenoid biosynthetic genes in the CsPSY overexpressed plants remained unaltered except that PDS and ZDS showed a minor increase. This study suggests that CsPSY plays a crucial role in citrus carotenoid biosynthesis and could be used as a means of engineering fruit crop for the production of carotenoids.

Lycopene-epsilon-cyclase pre-mRNA is alternatively spliced in Cara Cara navel orange (Citrus sinensis Osbeck).

Lycopene-epsilon-cyclase is one of the key enzymes related to alpha-carotene metabolism in plants. A full-length cDNA of 1300 bp encoding lycopene-epsilon-cyclase (Lyce) was generated from Cara Cara navel orange, a unique navel orange containing both lycopene and beta-carotene in its pulp, with little or no alpha-carotene. The gene had a 14 bp nucleotides deletion and caused a terminal mutation. DNA sequence corresponding to the deletion region revealed that two repeats of 6 bp (AGGTGT) were flanking the region in both Cara Cara and its original variety, Washington navel oranges, but a 2 bp (AT) insertion was only found in Cara Cara which explain the alternative splicing character of the gene.