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Background: With the continuous exploration and application of antibiotics, many common diseases have been treated while the evolution of drug-resistant bacteria has increased. The immediate raised of antibiotic-resistance makes it necessary to research special microorganisms for finding novel bioactive substances against drug-resistant bacteria. Insect-associated microbes have special metabolic pathways and are valuable resource base for the research and development of new antibiotics. The Odontotermes formosanus has formed a unique self-defense mechanismin the long-term evolution. Hence, nest of O. formosanus is a potential material for screening actinomycetes and compounds with bacteriostatic activity.Methods: The strain BYC17 was identified by morphological observation and 16S rDNA sequencing analysis, and the bacteriostasis test of BYC17 was carried on. The active component was separated and purified after screening, and the structure of the active monomer compound was determined by spectral analysis. Finally, the bacteriostatic effect of the active monomer compound was tested.Results: BYC17 was identified as Streptomyces showdoensis with antimicrobial activity against all three test bacteria. The monomer compound BYC17-01 was isolated from BYC17 and identified as izumiphenazine A. Under the concentration of 90 μg/6 mm filter paper, the inhibition zones of the monomer compound BYC17-01 against Staphylococcus aureus, Escherichia coli and Micrococcus tetragenus were 13.0, 9.0 and 11.1 mm respectively.Conclusions: This study demonstrates that izumiphenazine A produced by strain BYC17 hold the potential to be used against various human pathogenic microorganisms, particularly S. aureus and M. tetragenus .

The optimized extraction conditions of red pigments (RP) from bayberry (Myrica rubra) pomace obtained with response surface methodology were extraction pH, time, temperature, liquid/solid ratio as 1.4, 4.2 h, 56.1 °C and 12.6/1 ml/g, respectively. The RP were then purified by the macroporous resin, which indicated the resin LX-68 showed the maximum refined efficiency among the tested resins. Further solvent partition of the RP yielded ethyl acetate, n-butanol and water layers, in which the first fraction showed the strongest DPPH and hydroxyl radical scavenging activities with IC50 values of 2.13 μg/ml and 0.57 mg/ml, respectively, which were higher than those of BHA and mannitol used as a positive control. Following activity-oriented separation, (−)-epicatechin and procyanidin B2 were isolated from the ethyl acetate layer and were found to have excellent DPPH free radical scavenging activities with IC50 values of 2.87 and 2.06 μg/ml, respectively.

Aqueous enzymatic extraction (AEE) of oil from Myrica rubra kernels was performed. The four AEE parameters namely mixed enzyme (cellulose/neutral protease = 1/2, w/w) amount, liquid/solid ratio, extraction time, and temperature, were optimised by response surface methodology. The statistical analysis indicated that the enzyme amount, liquid/solid ratio, time, and the quadratics of liquid/solid ratio, and enzyme amount, as well as the interactions between time and temperature, showed significant effects on oil yield. The optimal extraction conditions for oil yield were mixed enzyme amount, liquid/solid ratio, time, temperature as 3.17% (w/w), 4.91 ml/g, 4 h and 51.6 °C. Under the optimum conditions, the experimental oil extraction yield was 31.15%. The GC–MS analysis showed that the oil was abundant in the unsaturated fatty acids (9-octadecenoic acid and 9,12-octadecadienoic acid accounting for more than 80%), and the AEE was more efficient method to extract polyunsaturated fatty acid than the organic solvent process.

The optimised extraction conditions of red pigments (RP) from Camellia japonica obtained with an orthogonal design L9(34) were solid/liquid ratio, temperature, pH and extraction time as 1/10, 60°C, 1.5 and 4h, respectively. The RP were then purified by the macroporous resin method, which showed the resin LX-68 was appropriate for purifying the pigments from C. japonica. The antioxidant activities of these pigments were also investigated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical in vitro model systems. The DPPH scavenging activity of pigment extract was comparable to that of standard butylated hydroxyanisole (BHA). The IC50 values of the RP and BHA were 4.55 and 4.17μgml-1, respectively. The pigments showed higher hydroxyl radical-scavenging activities than that of mannitol at the same concentration. Following activity-oriented separation, (-)-epicatechin was isolated as an active principle, which exhibited excellent DPPH free radical scavenging activities with IC50 5.08μgml-1.

Two main phytotoxic and antifungal phthalic acid butyl isobutyl ester (1) and radicinin (2) were isolated from the culture of Curvularia sp. FH01, a fungus residing in the Atractomorpha sinensis gut. The structures of isolated metabolites were established on the basis of spectral analysis. Metabolites 1 and 2 exhibited significant phytotoxic activity against the radical growth of Echinochloa crusgalli with their IC(50) values of 61.9 and 5.9 μg/mL, respectively, which were comparable to that 2,4-dichlorophenoxyacetic acid (2.0 μg/mL) used as a positive control. The antifungal test results showed that compound 2 possessed strong antifungal activity against Magnaporthe grisea (IC(50)=16.3 μg/mL) and Valsa mali (IC(50)=18.2 μg/mL). The findings of the present study suggest that bioactive properties of the fungus FH01 can be attributed to its major components, phthalic acid butyl isobutyl ester and radicinin, and both agents have a potential to be used as herbicide and fungicide.