Wen-Sheng Xiang

Optimization of culture conditions for hydrogen production by Ethanoligenens harbinense B49 using response surface methodology

The design of an optimum and cost-efficient medium for high-level production of hydrogen by Ethanoligenens harbinense B49 was attempted by using response surface methodology (RSM). Based on the Plackett-Burman design, Fe(2+) and Mg(2+) were selected as the most critical nutrient salts. Subsequently, the optimum combination of the selected factors and the sole carbon source glucose were investigated by the Box-Behnken design. Results showed that the maximum hydrogen yield of 2.21 mol/mol glucose was predicted when the concentrations of glucose, Fe(2+) and Mg(2+) were 14.57 g/L, 177.28 mg/L and 691.98 mg/L, respectively. The results were further verified by triplicate experiments. The batch reactors were operated under an optimized condition of the respective glucose, Fe(2+) and Mg(2+) concentration of 14.5 g/L, 180 mg/L and 690 mg/L, the initial pH of 6.0 and experimental temperature of 35+/-1(o)C. Without further pH adjustment, the maximum hydrogen yield of 2.20 mol/mol glucose was obtained based on the optimized medium with further verified the practicability of this optimum strategy.

Minimization of excess sludge production by in-situ activated sludge treatment processes--a comprehensive review.

The widespread application of conventional activated sludge treatment process has been employed to deal with a variety of municipal and industrial sewage. While the generation of waste activated sludge (WAS) was considerably huge, the management and disposal expenses were substantially costly. A promising process aimed for WAS reduction during the operation process is urgently needed. Thus, increasing attentions emphasizing on the improved or novel sludge reduction processes should be intensively recommended in the future. This review presents the current and emerging technologies for excess sludge minimization within the process of sewage treatment. The ultimate purpose of this paper is to guide or inspire researchers who are seeking feasible and promising technologies (or processes) to tackle the severe WAS problem.

A new quinoline derivative with cytotoxic activity from Streptomyces sp. neau50

A new quinoline derivative, methyl 8-(3-methoxy-3-methylbutyl)-2-methylquinoline-4-carboxylate (1), was isolated from the endophytic strain Streptomyces sp. neau50, and the structure was elucidated by extensive spectroscopic analysis. Compound 1 showed cytotoxicity against human lung adenocarcinoma cell line A549 with an IC(50) value of 29.3 μg mL(-1).

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).

Role of nsdA in negative regulation of antibiotic production and morphological differentiation in Streptomyces bingchengensis

To investigate the function of nsdA in Streptomyces bingchengensis, it was cloned and sequenced, which presented an 89.89% identity with that of S. coelicolor. The λRED-mediated PCR-targeting technique was used to create nsdA replacement in the S. bingchengensis_226541 chromosome. The nsdA disruption mutant, BC29, was obtained, which produced more pigment and spores than did the ancestral strain. HPLC analysis revealed that the disruption of nsdA efficiently increased milbemycin A4 production and nanchangmycin production by 1.5-fold and 9-fold, respectively. Complementation of the nsdA mutation restored the phenotype and antibiotic production. These results showed that nsdA negatively affected sporulation and antibiotic production in S. bingchengensis.

Four New Doramectin Congeners with Acaricidal and Insecticidal Activity from Streptomyces avermitilis NEAU1069

Four new doramectin congeners, 1–4, were isolated from Streptomyces avermitilis NEAU1069. The structures of 1–4 were elucidated on the basis of spectroscopic analysis, including 1D‐ and 2D‐NMR as well as HR‐ESI‐MS, ESI‐MS, UV, and IR, and comparison with literature data. All compounds exhibited noticeable acaricidal and insecticidal activities. Especially compound 2 was found to be the most potent pesticide of the compounds evaluated with the IC50 values of 10.2, 65.1 and 124.4 μg/ml against adult two‐spotted spider mites (Tetranychus urticae Koch), two‐spotted spider mite eggs, and Mythimna separata, respectively, which are comparable to those of commercial pesticide milbemycin A3/A4 as positive reference.

Isolation and identification of 5-hydroxyl-5-methyl-2-hexenoic acid from Actinoplanes sp. HBDN08 with antifungal activity.

A bioactivity-guided approach was employed to isolate and determine the chemical identity of bioactive constituents with antifungal activity from Actinoplanes sp. HBDN08. The structure of the antifungal metabolite was elucidated as 5-hydroxyl-5-methyl-2-hexenoic acid on the basis of spectral analysis. This compound showed strong in vitro antifungal activity against Botrytis cinerea, Cladosporium cucumerinum and Corynespora cassiicola, with an IC(50) of 32.45, 27.17, and 30.66 mg/L, respectively; however, it only moderately inhibited hyphal growth of Rhizoctonia solani with an IC(50) of 61.64 mg/L. The in vivo antifungal activity under greenhouse conditions demonstrated that 5-hydroxyl-5-methyl-2-hexenoic acid could effectively control the diseases caused by B. cinerea, C. cucumerinum and C. cassiicola with 71.42%, 78.63% and 65.13% control values at 350 mg/L, respectively. This strong antifungal activity suggests that 5-hydroxyl-5-methyl-2-hexenoic acid might be a promising candidate for new antifungal agents.

Reversal effects of two new milbemycin compounds on multidrug resistance in MCF-7/adr cells in vitro.

Development of agents to overcome multidrug resistance (MDR) is important in cancer chemotherapy, and the overexpression of P-glycoprotein (P-gp) is one of the major mechanisms of MDR. In this paper, we evaluated the effects of two new milbemycin compounds, milbemycin β(14) and secomilbemycin D, isolated from fermentation broth of S. bingchenggensis on reversing MDR of adriamycin-resistant human breast carcinoma (MCF-7/adr) cells. We observed that the both milbemycins (5 μM) showed strong potency to increase adriamycin cytotoxicity toward MCF-7/adr cells with reversal fold (RF) of 13.5 and 10.59, respectively. In addition, the mechanisms of milbemycins on reversing P-gp-mediated MDR demonstrated that they significantly increased the accumulations of adriamycin and Rh123 via inhibiting P-gp efflux in MCF-7/adr cells. Furthermore, the results also revealed that milbemycin β(14) and secomilbemycin D could regulate down the expression of P-gp, but not affect the expression of MDR1 gene. In conclusion, our observations suggest that the two new milbemycin compounds probably represent the promising agents for reversing MDR in cancer therapy.