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The improper treatment of landfill leachates is one of the major problems associated with waste landfilling and causes serious environmental pollution at waste landfill sites and their surroundings. To develop a suitable landfill leachate treatment system and to minimize the risk of environmental pollution, it is important to characterize seasonal and temporal variations of landfill leachates. This study investigated the leachate quality of the Nam Son waste landfill in Hanoi, Vietnam in 2017–2019 and characterized the potential risks of landfill leachate using a leachate pollution index (LPI). The results of this study showed that the seasonal and temporal variation of the overall LPI during the monitoring period was small and in the range of 20–25 (values 2.5 times higher than the maximum permissible limits of Vietnam National Technical Regulation on Industrial Wastewater). The LPI sub-indices attributed to organic and inorganic pollutants were major components of the LPI. Especially, the annually averaged values of LPI of inorganic pollutants were 7.7 times higher than the maximum permissible limits, suggesting that the treatment of inorganic pollutants, such as ammonium-nitrogen (NH4+–N) and total nitrogen (TN), is highly required at Nam Son landfill to prevent environmental pollution surrounding the landfill site.

A high-performance liquid chromatography with electrospray ionization ion trap tandem mass spectrometry method was developed and validated for the robust profiling and characterization of biosynthetic congeners in the 2-deoxy-aminocyclitol istamycin pathway, from the fermentation broth of Streptomyces tenjimariensis ATCC 31603. Gradient elution on an Acquity CSH C18 column was performed with a gradient of 5 mM aqueous pentafluoropropionic acid and 50% acetonitrile. Sixteen natural istamycin congeners were profiled and quantified in descending order; istamycin A, istamycin B, istamycin A0, istamycin B0, istamycin B1, istamycin A1, istamycin C, istamycin A2, istamycin C1, istamycin C0, istamycin X0, istamycin A3, istamycin Y0, istamycin B3, and istamycin FU-10 plus istamycin AP. In addition, a total of five sets of 1- or 3-epimeric pairs were chromatographically separated using a macrocyclic glycopeptide-bonded chiral column. The lower limit of quantification of istamycin-A present in S. tenjimariensis fermentation was estimated to be 2.2 ng/mL. The simultaneous identification of a wide range of 2-deoxy-aminocyclitol-type istamycin profiles from bacterial fermentation was determined for the first time by employing high-performance liquid chromatography with tandem mass spectrometry analysis and the separation of istamycin epimers. [ABSTRACT FROM AUTHOR]

A uridine diphosphate-glucose:sterol glycosyltransferase-encoding gene was isolated and cloned from the established fosmid library of Micromonospora rhodorangea ATCC 27932 that usually produces the aminoglycoside antibiotic geneticin. The gene consists of 1,185 base pairs and encodes a 41.4 kDa protein, which was heterologously expressed in Escherichia coli BL21(DE3). In silico analyses of the deduced gene product suggested that it is a member of the family 1 glycosyltransferases. The recombinant protein MrSGT was able to catalyze the transfer of a glucosyl moiety onto the C-3 hydroxy function in sterols (β-sitosterol, campesterol, and cholesterol), resulting in the corresponding steryl glucosides (β-sitosterol-3-O-β-D-glucoside, campesterol-3-O-β-D-glucoside, and cholesterol-3-O-β-D-glucoside). This enzyme prefers phytosterols to cholesterol, and also shows substrate flexibility to some extent, in that it could recognize a number of acceptor substrates.