Extraction of Flavonoids and Polyphenols from Coronatinetreated Mulberry Leaves and Evaluation of Their Antibacterial Activity against Pseudomonas syringae

Flavonoids and polyphenols are the main secondary metabelites in mulberry leaves, which have multiple biological functions such as antibacterial activity, free radical scavenging activity and antioxidant activity. In this paper, the parameters for the extraction of flavonoids and palyphenols from eoronatine （ COR）- treated mulberry leaves were optimized, and the components of the extracts were analyzed by high performance liquid chromatography （ HPLC）, and their antibacterial activity against Pseudomonas syringae, which causes mulberry bacterial blight, was evaluated in vitro to explore the mechanism how COR acted as a plant immune elicitor to improve the resistance of mulberry to bacterial blight. The results showed that ethanol concentration of 70%, extraction temperature of 80 ℃, extraction duration of 6 h and solid-liquid ratio of 1 ： 40 were the optimal parameters for the extraction of flavonoids and polyphenols from mulberry leaves. Flavonoids and polyphenols were mostly distributed in ethyl acetate and n-butyl alcohol fractions which showed better antibacterial activity than petroleum ether, dichloromethane and water fractions. Meanwhile, the antibacterial activity of ethyl acetate and n-butyl alcohol fractions of COR-treated mulberry leaves were more evident than that of water-treated mulberry leaves. Scanning electron microscopy showed that flavonoids and pelyphenols inhibited the growth of pathogenic bacteria by changing cell morphology, damaging cell wall structure and unbalancing cell osmotic pressure. HPLC analysis confirmed the contents of morin, quercetin, quereitrin, kaempferol, chlorogenic acid and rutin were increased to a different extent in COR-treated mulberry leaves. So it can be concluded that the increased contents of flavonoids and polyphenols induced by COR may be one of the reasons for the enhanced resistance to mulberry bacterial blight.

Isolation,Mutagenesis,Identification and Cellulase Properties of a Mulberry Branches Decomposing Fungus from Insect

In order to utilize mulberry branches efficiently and reduce environment pollution, a strain named A1 was isolated from the intestinal tract of Acr/da Chinensis using Congo red staining method on the plate of carboxymethyl cellulose sodium （CMC-Na） medium and mulberry branch powder culture medium. The strain A1 was mutagenized by uhraviolet radiation and the strain Z3 with a significantly improved specific activity of filter paper enzyme was screened. Enzymatic characteristics, degradation ability of cellulose and taxonomic status of A1 and Z3 were also studied in this paper. The results showed that filter paper enzyme specific activity of Z3 increased 74.47% than that of A1 and the property of enzyme production was steady. The optimum pH values of filter paper enzyme produced by A1 and Z3 were 4. 6 and 3.8 respectively and the optimum temperatures were 45 and 50 ℃, respectively. When CMC-Na was used as substrate, Vmax of the two strains was similar while Km of Z3 was lower than that of A1 , which indicated that Z3 had a strong affinity for the substrate. Enzymes produced by Z3 were more resistant to high temperature. Strains A1 and Z3 could grow well on the culture mediums with mulberry branch powder as carbon source, but Z3 grew better than A1. A1 and Z3 were preliminarily identified as AspergiUus according to the morphological identification.

Effects of Dichlorvos on Immune Enzyme Activities in the Serum of Macrobrachium nipponense

In this study,the effects of three different concentrations（0.5,0.25 and 0.125μl/L）of dichlorvos solution on phenoloxidase（PO）activity,hemolysin activity,peroxidase（POD）activity and antibacterial activity in the serum of Macrobrachium nipponense during four days were investigated.The results indicated that phenoloxidase activity,hemolysin activity,peroxidase activity and antibacterial activity in the serum of Macrobrachium nipponense were improved under the stress of dichlorvos during a short time.With the extension of stress duration and increase of dichlorvos concentration,the activities of various immunological indices were inhibited due to the cumulative effect of dichlorvos in vivo;overall,the reduction increased gradually with the extension of stress duration.