Characterization of inthomycin biosynthetic gene cluster revealing new insights into carboxamide formation.

Inthomycins are polyketide antibiotics which contain a terminal carboxamide group and a triene chain. Inthomycin B (1) and its two new analogues 2 and 3 were isolated from the crude extract of Streptomyces pactum L8. Identification of the gene cluster for inthomycin biosynthesis as well as the 15N-labeled glycine incorporation into inthomycins are described. Combined with the gene deletion of the rare P450 domain in the NRPS module, a formation mechanism of carboxamide moiety in inthomycins was proposed via an oxidative release of the assembly chain assisted by the P450 domain.

[Effect of pH on precipitate composition during phosphorus recovery as struvite from swine wastewater].

Phosphorus recovery as struvite from swine wastewater was carried out. Fourier transform infrared spectroscopy (FTIR), Xray diffraction (XRD) and mass balance analysis were utilized to analyze the species of precipitated minerals under different pH conditions. Results showed that increasing pH from 8.0 to 9.0 resulted in the increase of phosphorus removal efficiency from 85% to 94%. A relatively stable phosphorus removal at 94% was observed at pH 9.0-11.0, whereas a drastic decline to 70% was detected when pH increased to 12.0. The minerals precipitated in the deposits were struvite (MgNH4PO4 x 6H2O), K-struvite (MgKPO4 x 6H2O), amorphous calcium phosphate [Ca3 (PO4 )2 (x) xH2O, ACP] and Mg (OH)2. Struvite was the dominant species in the precipitate at pH 8.0-9.0. Enhancing pH from 9.0 to 10.0 resulted in struvite decline and gave rise to K-struvite and ACP steadily. With regard to highly alkaline conditions at pH above 10, drastic decrease of struvite and rapid increase of ACP and Mg(OH)2 were observed. Maximum concentration of K-struvite was obtained at pH 11.0, following a sharp decline to pH 12.0. Controlling pH between 8.0 and 9.0 could inhibit other minerals formation and obtain the highly pure struvite crystal product.

A novel macrocyclic lactone with insecticidal bioactivity from Streptomyces microflavus neau3.

A novel macrocyclic lactone (1) was isolated from the fermentation broth of Streptomycesmicroflavus neau3, and the structure was elucidated by extensive spectroscopic analysis. Compound 1 showed high acaricidal activity against adult mites (IC(50)=11.1 µg mL(-1)), and nematocidal activity against Caenorhabditis elegans (IC(50)=17.4 µg mL(-1)), especially the acaricidal activity against mite eggs with an IC(50) of 37.1 µg mL(-1), which was relative higher than that of the commercial acaricide and nematocide milbemycins A(3)/A(4).

Phosphorus recovery from synthetic swine wastewater by chemical precipitation using response surface methodology.

With synthetic swine wastewater, central composite design using response surface methodology was employed to investigate the effects of pH value and concentrations of ammonium, phosphate, magnesium and calcium on phosphorous recovery. P recovery efficiency with the range of 53-99% was observed in the experimental runs. Results showed that magnesium ammonium phosphate were the only crystals, mixed with amorphous calcium precipitates, in the deposits. According to the regression quadratic model, the linear and quadratic terms of PO(4)(3-)-P and Mg had significant effects on the P recovery amount. With regard to the interaction terms, pH x NH(4)(+)-N, PO(4)(3-)-P x Mg, PO(4)(3-)-P x Ca and Mg x Ca showed significant influences. A maximum P recovery amount of 299.25 mg/L was achieved at optimized conditions with pH 9.7, NH(4)(+)-N 456 mg/L, PO(4)(3-)-P 300 mg/L, Mg(2+) 264 mg/L and Ca(2+) 59 mg/L, respectively.