SignificanceNatural products biosynthesized by cryptic gene clusters represent a largely untapped source for drug discovery. However, mining of these products by promoter engineering is restricted by the lack of streamlined genetic tools, especially in nonmodel biosynthetic gene cluster (BGC)-rich bacteria. Here, we describe the discovery of a pair of bacteriophage recombinases and application of recombinase-assisted promoter engineering to rapidly identify and activate several cryptic biosynthetic gene clusters in two Burkholderiales strains that currently lack effective genetic tools. Construction of an efficient genome engineering platform in a natural product producer expedites mining of cryptic BGCs in their native backgrounds, and host melioration for yield or structure optimization. This strategy enables potentially scalable discovery of novel metabolites with intriguing bioactivities from many other bacteria.

The use of conventional water and wastewater treatment processes becomes increasingly challenged with the identification of more and more contaminants, rapid growth of population and industrial activities, and diminishing availability of water resources. Three emerging treatment technologies, including membrane filtration, advanced oxidation processes (AOPs), and UV irradiation, hold great promise to provide alternatives for better protection of public health and the environment and thus are reviewed in this paper. The emphasis was placed on their basic principles, main applications, and new developments. Advantages and disadvantages of these technologies are compared to highlight their current limitations and future research needs. It can be concluded that, along with the growing knowledge and the advances in manufacturing industry, the applications of these technologies will be increased at an unprecedented scale.Key words: water treatment, wastewater treatment, membrane filtration, ozonation, advanced oxidation processes, UV irradiation.

The effect of temperature from 10 "C to 35 C on the growth, total lipid content, and fatty acid composition of three species of tropical marine microalgae, Isochrysis sp., Nitzschia closterium, N. paleacea (formerlyfrustulum), and the Tahitian Isochrysis sp. (T.ISO), was investigated.Cultures of N. closterium, Isochrysis sp. and T.ISO grew very slowly at 35 C, while N. closterium did not grow at temperatures higher than 30 "C or lower than 20 "C. N. paleacea was low-temperature tolerant, with cells growing slowly at 10 C. N. paleacea produced the highest percentage of lipids at 10 C, while the other species produced maximum amounts of lipid at 20 °C. None of the species maintained high levels of polyunsaturated fatty acids (PUFAs) at high growth temperature and there was a significant inverse relationship between the percentage of PUFAs and temperature for N. paleacea. A curved relationship was found between temperature and percentage of PUFA for N. closterium and tropical Isochrysis sp., with the maximum production of PUFA at 25 C and 20 "C, respectively. The two Nitzschia species produced higher levels of the essential fatty acid eicosapentaenoic acid [20:5(n-3)] at lower growth temperatures, but the two Isochrysis species had little change in percentage of 20:5(n-3) with temperature. Only T.ISO had the highest percentage of 22:6(n-3) at lowest growth temperature (11.4% total fatty acids at 10 "C).

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This work studied the influences of formation of BSA/ι-carrageenan complexes on the binding, stability, and antioxidant activity of curcumin. In the presence of BSA and ι-carrageenan, curcumin gives higher intensities of absorption and fluorescence than free curcumin and curcumin only combined with BSA. The added ι-carrageenan is observed to promote curcumin for quenching the instrinsic fluorescence of BSA. These results are explained in terms of the formation of BSA/ι-carrageenan complexes, which help to stabilize the folded structure of BSA for providing curcumin with a more hydrophobic microenvironment. The small difference in anisotropy values of curcumin with BSA alone and of BSA/ι-carrageenan complexes suggests that ι-carrageenan acts as outer stretch conformation in BSA/ι-carrageenan complexes but does not directly disturb the hydrophobic pockets inside BSA, where curcumin is hydrophobically located. The determined values of the binding constant are higher for curcumin with BSA/ι-carrageenan complexes than with BSA alone. Moreover, BSA/ι-carrageenan complexes are found to be superior to single BSA for enhancing the stability and DPPH radical-scavenging ability of curcumin.