Identification and Heterologous Reconstitution of a 5-Alk(en)ylresorcinol Synthase from Endophytic Fungus \u3ci\u3eShiraia\u3c/i\u3e sp. Slf14

A new type III polyketide synthase gene (Ssars) was discovered from the genome of Shiraia sp. Slf14, an endophytic fungal strain from Huperzia serrata. The intron-free gene was cloned from the cDNA and ligated to two expression vectors pET28a and YEpADH2p-URA3 for expression in Escherichia coli BL21(DE3) and Saccharomyces cerevisiae BJ5464, respectively. SsARS was efficiently expressed in E. coli BL21(DE3), leading to the synthesis of a series of polyketide products. Six major products were isolated from the engineered E. coli and characterized as 1,3-dihydroxyphenyl-5-undecane, 1,3-dihydroxyphenyl-5-cis-6\u27-tridecene,1,3-dihydroxyphenyl-5-tridecane, 1,3-dihydroxyphenyl-5-cis-8\u27-pentadecene, 1,3-dihydroxyphenyl-5-pentadecane and 1,3-dihydroxyphenyl-5-cis-10\u27-heptadecene, respectively, based on the spectral data and biosynthetic origin. Expression of SsARS in the yeast also led to the synthesis of the same polyketide products, indicating that this enzyme can be reconstituted in both heterologous hosts. Supplementation of soybean oil into the culture of E. coli BL21(DE3)/SsARS increased the production titers of 1-6 and led to the synthesis of an additional product, which was identified as 5-(8\u27Z,11\u27Z-heptadecadienyl)resorcinol. This work thus allowed the identification of SsARS as a 5-alk(en)ylresorcinol synthase with flexible substrate specificity toward endogenous and exogenous fatty acids. Desired resorcinol derivatives may be synthesized by supplying corresponding fatty acids into the culture medium

Combined Ultrasonic Elliptical Vibration and Chemical Mechanical Polishing of Monocrystalline Silicon

An ultrasonic elliptical vibration assisted chemical mechanical polishing(UEV-CMP) is employed to achieve high material removal rate and high surface quality in the finishing of hard and brittle materials such as monocrystalline silicon, which combines the functions of conventional CMP and ultrasonic machining. In theultrasonic elliptical vibration aided chemical mechanical polishingexperimental setup developed by ourselves, the workpiece attached at the end of horn can vibrate simultaneously in both horizontal and vertical directions. Polishing experiments are carried out involving monocrystalline silicon to confirm the performance of the proposed UEV-CMP. The experimental results reveal that the ultrasonic elliptical vibration can increase significantly the material removal rate and reduce dramatically the surface roughness of monocrystalline silicon. It is found that the removal rate of monocrystalline silicon polished by UEV-CMP is increased by approximately 110% relative to that of conventional CMP because a passive layer on the monocrystalline silicon surface, formed by the chemical action of the polishing slurry, will be removed not only by the mechanical action of CMP but also by ultrasonic vibration action. It indicates that the high efficiency and high quality CMP of monocrystalline silicon can be performed with the proposed UEV-CMP technique

Combined Ultrasonic Elliptical Vibration and Chemical Mechanical Polishing of Monocrystalline Silicon

An ultrasonic elliptical vibration assisted chemical mechanical polishing(UEV-CMP) is employed to achieve high material removal rate and high surface quality in the finishing of hard and brittle materials such as monocrystalline silicon, which combines the functions of conventional CMP and ultrasonic machining. In theultrasonic elliptical vibration aided chemical mechanical polishingexperimental setup developed by ourselves, the workpiece attached at the end of horn can vibrate simultaneously in both horizontal and vertical directions. Polishing experiments are carried out involving monocrystalline silicon to confirm the performance of the proposed UEV-CMP. The experimental results reveal that the ultrasonic elliptical vibration can increase significantly the material removal rate and reduce dramatically the surface roughness of monocrystalline silicon. It is found that the removal rate of monocrystalline silicon polished by UEV-CMP is increased by approximately 110% relative to that of conventional CMP because a passive layer on the monocrystalline silicon surface, formed by the chemical action of the polishing slurry, will be removed not only by the mechanical action of CMP but also by ultrasonic vibration action. It indicates that the high efficiency and high quality CMP of monocrystalline silicon can be performed with the proposed UEV-CMP technique

New Insights into Ion Adsorption Type Rare-Earths Mining—Bacterial Adsorption of Yttrium Integrated with Ammonia Nitrogen Removal by a Fungus

Ion adsorption-type heavy rare earths found in southern China are important ore resources, whose yttrium(Y)-group rare-earth elements account for 90% of the total mass of rare earths known on the planet. At present, ammonia-nitrogen wastewater from extraction of rare earths pose threats to the environment. A bacterial strain (Bacillus sp. ZD 1) isolated from the “Foot Cave” mining area was used for adsorption of Y3+. Its adsorption capacity reached 428 μmol/g when the initial concentration of Y3+ was 1.13 mM. Moreover, 50 mg of Bacillus sp. ZD 1 (converted to dry mass) could completely adsorb Y3+ in the mother solution of mixed rare earths from the rare-earth mining area. Ammonia nitrogen in the remaining solution after adsorption was removed through denitrification using a fungus named Galactomyces sp. ZD 27. The final concentration of ammonia nitrogen in wastewater was lower than Indirect Emission Standard of Pollutants for Rare-earth Industry (GB 26451-2011). Furthermore, the resulting fungal cells of Galactomyces sp. ZD 27 could be used to produce single cell proteins, whose content accounted for 70.75% of the dry mass of cells. This study offers a new idea for integrated environmentally-friendly extraction and ecological restoration of the mining area in southern China

Natural Products from the Genus Tephrosia

The genus Tephrosia, belonging to the Leguminosae family, is a large pantropical genus of more than 350 species, many of which have important traditional uses in agriculture. This review not only outlines the source, chemistry and biological evaluations of natural products from the genus Tephrosia worldwide that have appeared in literature from 1910 to December 2013, but also covers work related to proposed biosynthetic pathways and synthesis of some natural products from the genus Tephrosia, with 105 citations and 168 new compounds

New Insights into the Glycosylation Steps in the Biosynthesis of Sch47554 and Sch47555

Sch47554 and Sch47555 are antifungal compounds from Streptomyces sp. SCC‐2136. The availability of the biosynthetic gene cluster made it possible to track genes that encode biosynthetic enzymes responsible for the structural features of these two angucyclines. Sugar moieties play important roles in the biological activities of many natural products. An investigation into glycosyltransferases (GTs) might potentially help to diversify pharmaceutically significant drugs through combinatorial biosynthesis. Sequence analysis indicates that SchS7 is a putative C‐GT, whereas SchS9 and SchS10 are proposed to be O‐GTs. In this study, the roles of these three GTs in the biosynthesis of Sch47554 and Sch47555 are characterized. Coexpression of the aglycone and sugar biosynthetic genes with schS7 in Streptomyces lividansK4 resulted in the production of C‐glycosylated rabelomycin, which revealed that SchS7 attached a d‐amicetose moiety to the aglycone core structure at the C‐9 position. Gene inactivation studies revealed that subsequent glycosylation steps took place in a sequential manner, in which SchS9 first attached either an l‐aculose or l‐amicetose moiety to 4′‐OH of the C‐glycosylated aglycone, then SchS10 transferred an l‐aculose moiety to 3‐OH of the angucycline core

A new diketopiperazine from South China Sea marine sponge <i>Callyspongia</i> sp.

<div><p>Further chemical investigation on the marine sponge <i>Callyspongia</i> sp. collected from South China Sea led to the isolation of a new diketopiperazine, named callysponine A (<b>1</b>), as well as four known diketopiperazines, namely cyclo-(Gly-Pro) (<b>2</b>), cyclo-(Thr-Pro) (<b>3</b>), cyclo-(Ile-Pro) (<b>4</b>) and cyclo-(Pro-Pro) (<b>5</b>). The new structure was determined on the basis of NMR and MS analysis, and the absolute stereochemistry was defined by analysis of the coupling constants and optical rotation. The structures of the known compounds were identified by comparing their spectroscopic data with those reported in the literature. Compounds <b>1</b>–<b>5</b> did not inhibit the growth of HepG2 (hepatoma carcinoma cell), A549 (lung carcinoma cell) and HeLa (cervical cancer cell) cell lines.</p></div

Diversified Chemical Structures and Bioactivities of the Chemical Constituents Found in the Brown Algae Family Sargassaceae

Sargassaceae, the most abundant family in Fucales, was recently formed through the merging of the two former families Sargassaceae and Cystoseiraceae. It is widely distributed in the world’s oceans, notably in tropical coastal regions, with the exception of the coasts of Antarctica and South America. Numerous bioactivities have been discovered through investigations of the chemical diversity of the Sargassaceae family. The secondary metabolites with unique structures found in this family have been classified as terpenoids, phlorotannins, and steroids, among others. These compounds have exhibited potent pharmacological activities. This review describes the new discovered compounds from Sargassaceae species and their associated bioactivities, citing 136 references covering from March 1975 to August 2023

A new 1,2-ethanedione benzofurane derivative from <i>Tephrosia purpurea</i>

<div><p>A new 1,2-ethanedione benzofurane derivative, purpdione (<b>1</b>), was isolated from <i>Tephrosia purpurea</i>, together with seven known flavonoids, purpurenone (<b>2</b>), pongamol (<b>3</b>), ovalitenin A (<b>4</b>), karanjin (<b>5</b>), lanceolatin B (<b>6</b>), tachrosin (<b>7</b>) and villosinol (<b>8</b>). The new structure was elucidated based on the analysis of its spectroscopic data. The structures of the known compounds were identified by comparing their spectroscopic data with those reported in the literature. The isolates exhibited marginal ability to inhibit the settlement of barnacle (<i>Balanus reticulatus</i>).</p></div