Novel α-Amylase Inhibitor Hemi-Pyocyanin Produced by Microbial Conversion of Chitinous Discards

α-Amylase inhibitors (aAIs) have been applied for the efficient management of type 2 diabetes. The aim of this study was to search for potential aAIs produced by microbial fermentation. Among various bacterial strains, Pseudomonas aeruginosa TUN03 was found to be a potential aAI-producing strain, and shrimp heads powder (SHP) was screened as the most suitable C/N source for fermentation. P. aeruginosa TUN03 exhibited the highest aAIs productivity (3100 U/mL) in the medium containing 1.5% SHP with an initial pH of 7–7.5, and fermentation was performed at 27.5 °C for two days. Further, aAI compounds were investigated for scaled-up production in a 14 L-bioreactor system. The results revealed a high yield (4200 U/mL) in a much shorter fermentation time (12 h) compared to fermentation in flasks. Bioactivity-guided purification resulted in the isolation of one major target compound, identified as hemi-pyocyanin (HPC) via gas chromatography-mass spectrometry and nuclear magnetic resonance. Its purity was analyzed by high-performance liquid chromatography. HPC demonstrated potent α-amylase inhibitory activity comparable to that of acarbose, a commercial antidiabetic drug. Notably, HPC was determined as a new aAI. The docking study indicated that HPC inhibits α-amylase by binding to amino acid Arg421 at the biding site on enzyme α-amylase with good binding energy (−9.3 kcal/mol) and creating two linkages of H-acceptors.     

增效剂对菜蚜茧蜂杀虫剂敏感性的影响

以田间菜蚜茧蜂为试虫,采用药膜法研究了增效剂胡椒基丁醚(PB)、磷酸三苯酯(TPP)和马来酸二乙酯(DEM)对6种杀虫剂的增效作用。结果表明,三种增效剂对6种杀虫剂均有显著增效作用,其大小依次为PB>DEM>TPP。PB对甲胺磷、阿维菌素、氟虫腈、氰戊菊酯、氯氰菊酯和吡虫啉的增效比达5.0～9.6倍。TPP和DEM对甲胺磷、DEM对氟虫腈的增效比达2.6～3.0倍,但TPP和DEM对阿维菌素、氰戊菊酯和氯氰菊酯、TPP对氟虫腈的增效比均在1.9倍以下。PB、TPP和DEM对吡虫啉的增效比分别高达9.6、6.8和8.2倍。体内抑制试验结果显示,PB、TPP和DEM对菜蚜茧蜂AChE活性无明显抑制作用,而PB和TPP对羧酸酯酶(CarE)、DEM对谷胱甘肽S转移酶(CST)活性有显著抑制作用。由此认为,菜蚜茧蜂对所用的6种杀虫剂的耐药性与多功能氧化酶(MFO)、CarE和GST的解毒作用有关。     

丙烯酸树脂包膜尿素肥料研制及其控释效果

采用丙烯酸树脂为包膜材料,以NBPT（N-丁基硫代磷酰三胺）和DCD（双氰胺）为生化抑制剂,利用流化床对尿素进行涂层生化抑制剂及包膜,制备4种包膜肥料,对这些包膜肥料在水中的控释效果进行了研究。结果表明,采用此技术制备的包膜肥料,表面成膜完整,包膜物质在成膜时分布均匀、与尿素肥心接合紧密,表面光滑。NBPT和DCD与肥心结合严密,包膜层紧覆于抑制剂的外表。包膜可有效控制尿素的溶出,在水中的控释时间为19～30d。初期溶出率远远小于15％,微分溶出率基本上在0．25％～2．5％之间;在水中尿素累积溶出特征符合一元二次方程模型,尿素释放曲线呈“S”形。     

Emerging technologies for the chemical control of root parasitic weeds

Parasitic plants in the Orobanchaceae family include devastating weed species, such as Striga, Orobanche, and Phelipanche, which parasitize major crops, drastically reduces crop yields and cause economic losses of over a billion US dollars worldwide. Advances in basic research on molecular and cellular processes responsible for parasitic relationships has now achieved steady progress through advances in genome analysis, biochemical analysis and structural biology. On the basis of these advances it is now possible to develop chemicals that control parasitism and reduce agricultural damage. In this review we summarized the recent development of chemicals that can control each step of parasitism from strigolactone biosynthesis in host plants to haustorium formation.     

直接种间电子传递对缓解厌氧消化抑制效应的研究进展

厌氧消化是将生物质废弃物进行资源化利用的有效途径之一。然而,复杂的原料性质以及反应器高负荷的运行条件会使厌氧消化过程产生多种抑制效应,易导致反应器运行不稳定,产气效率低等问题。因此,提升厌氧消化反应器运行性能、减缓抑制效应成为当前的研究热点。区别于以氢气和甲酸为媒介的间接种间电子传递（Mediated Interspecies Electron Transfer,MIET）过程,微生物间的直接种间电子传递（Direct Interspecies Electron Transfer,DIET）能够在菌群间直接进行电子转移,传递效率更高。DIET的建立有助于强化厌氧反应的稳定性,提高反应效率,减缓抑制效应。基于此,该文总结了DIET的研究进展,分析了主要的种间电子传递机制,探讨了DIET对不同类型抑制效应的缓解作用,归纳了DIET潜在微生物的富集效果;在此基础上展望了DIET在减缓厌氧消化抑制效应方面的重点研究方向和应用前景。