Microbial production of 1,3-propanediol from glycerol by Klebsiella pneumoniae under micro-aerobic conditions up to a pilot scale

1,3-Propanediol (1,3-PD) can be produced from glycerol by Klebsiella pneumoniae under micro-aerobic conditions. Recently, this fed-batch fermentation process has been successfully scaled up to 1 m³. The final 1,3-PD concentration, molar yield and volumetric productivity of 72 g l⁻¹, 57% and 2.1 g l⁻¹ h⁻¹, respectively, are close to those of 75 g l⁻¹, 61%, and 2.2 g l⁻¹ h⁻¹ under anaerobic conditions. This process would be suitable for the production of 1,3-PD on a large scale.     

Effect of UV Radiation and Other Abiotic Stress Factors on DNA of Different Wild Plant Species Grown in Three Successive Seasons in Alpine and Subalpine Regions

Plants in natural ecosystems are exposed to a combination of UV radiation, ionizing radiation (IR) and other abiotic factors. These factors change with the altitude. We investigated DNA alterations of some wild plants of different plant families in natural ecosystems at three altitudes in Rila Mountain, Bulgaria (1500, 1782, and 2925 m above sea level (a.s.l.) exposed to UV radiation, IR and other abiotic stresses, to assess the tolerance of plant species to the changing environmental conditions in three successive growth seasons. For this purpose, physicochemical, cytogenetic, and molecular methods were applied. DNA damage was assessed by micronucleus test and molecular method comet assay adapted and applied by us to wild plant species from Onagraceae, Rosaceae, Boraginaceae, Saxifragaceae, Orobanchaceae, Asteraceae and Poaceae families, growing at three different altitudes. Variability in the DNA sensitivity and the level of tolerance was observed among the plant species in response to combined abiotic factors assessed by induced DNA damage and gross beta activity. The studied representatives of Poaceae were less susceptible than the other studied species at all three altitudes and showed close level of DNA injuries to that of unaffected control plant grown in laboratory conditions. The lower levels of DNA damage of these wild plant species corresponded to their lower ability to accumulate radionuclides. There was a particularly pronounced low level of DNA injuries in the plant species at the highest altitude. The level of DNA damage showed correlation with the values of some abiotic environmental factors. The results would contribute to the elucidation of the extent of adaptation of plant species to the continuously changing environment and would be useful in selecting sensitive herbaceous monitor species for environmental impact assessment at mountain and alpine sites.     

基于生态位理论研究群落构建的方法进展

理解群落构建过程可以解释生物多样性格局的形成和维持,对于生物多样性保护起到关键作用。生态位理论是群落构建研究的核心框架之一。该理论认为群落构建是生物作用和非生物作用将区域物种库中的物种选入局域群落的确定过程。近年来,随着该领域受到的关注越来越多,研究者不但从物种、谱系或功能等生物多样性维度来研究群落构建,所使用的多样性指数、零模型算法和物种库界定方式等也多种多样。本文回顾了从生物多样性不同维度研究群落构建的优势与局限,总结了群落构建过程中构建零模型和界定物种库时需要注意的一些问题,介绍了部分群落构建研究的最新方法学进展和研究成果。最后,结合近年来的研究案例提出了对未来群落构建研究的一些建议。     

固态发酵下酵母自溶的工艺优化

固态下酵母自溶可以有效促进菌体内多种活性物质的释放,进而提高酵母类产品的品质。通过优化自溶温度、自溶时间及自溶促进剂锌离子浓度以获得固态发酵下酵母自溶的最佳工艺,对固态发酵物料中游离氨基酸、可溶性蛋白、α-氨基氮含量和A260/A280等指标的分析来确定固态酵母自溶工艺条件,在此基础上以自溶温度40 ℃、50 ℃、55 ℃;作用时间12、18、24 h;锌离子添加浓度2、4、8 mg/kg设置L9(33)正交试验,进一步优化固态酵母自溶的工艺参数。结果表明酵母自溶的最佳工艺条件为：自溶温度55 ℃、作用时间18 h、锌离子浓度2 mg/kg,此时其可溶性蛋白含量可达9.31 mg/g、游离氨基酸14.36 mg/g、α-氨基氮10.16 μg/g、A260/A280为1.73。经工艺优化后,可显著提高酵母自溶产物可溶性蛋白、游离氨基酸和α-氨基氮的含量,从而明显提高了复合菌培养物的品质。     

HS-GC/MS法分析乌龙茶挥发性成分

本试验旨在采用静态顶空-气相色谱/质谱法(HS-GC/MS)建立起一种快速测定分析以金观音为代表的乌龙茶中挥发物的方法。本方法利用单因素试验结合L9(34)正交试验,以出峰个数和总峰面积为考察指标,确定了顶空平衡温度、平衡时间、茶/Na Cl以及加样量4种因素的最佳萃取条件,并以此方法对金观音的挥发性成分进行了分析。结果表明,平衡温度对出峰个数和总峰面积的影响最大,而平衡时间的影响最小。试验得出的顶空进样的最优条件为:平衡温度80℃,平衡时间60 min,茶/Na Cl为1∶2,加样量为0. 5 g。在此萃取条件下能够得到104种物质,这些物质能更真实地反映金观音香气成分的化学构成,为以金观音为代表的乌龙茶的开发利用提供有价值的数据。     

Effect of stressful conditions on the carotenogenic activity of a Colombian strain of Dunaliella salina

The objective was evaluate the carotenogenic activity of Dunaliella salina isolated from the artificial salt flats of municipality of Manaure (Department of La Guajira, Colombia). Two experimental testings were designed, in triplicate, to induce the reversibility of the cell tonality depending on the culture conditions. In the first test (A), to induce the reversibility from green to red tonality in D. salina cells, these were cultured in J/1 medium at a concentration of 4.0 M NaCl, 390 µmol m^?2 s^?1, 0.50 mM KNO₃. In the second test (B), to induce the reversibility from red to green cell tonality, the cultures were maintained in J/1 medium 1 M NaCl, 190 µmol m^?2 s^?1, 5.0 mM KNO₃ and pH 8.2. The population growth was evaluated by cell count and the pigment content was performed by spectrophotometric techniques. It was found that in both tests the culture conditions influenced the population growth and the pigments production of D. salina. There was a significant difference between the mean values of total carotenoids in the test A with 9.67 ± 0.19 μg/ml and second test with 1.54 ± 0.08 μg/ml at a significance level of p < 0.05. It was demonstrated that the culture conditions of test A induce the production of lipophilic antioxidants, among these carotenoids. The knowledge of the stressful conditions for the production of carotenoids from D. salina isolated from artificial saline of Manaure opens a field in implementation of this biotic resource for biotechnological purposes, production of new antibiotics, nutraceuticals and/or biofuels production.     

miR‐148a inhibits early relapsed colorectal cancers and the secretion of VEGF by indirectly targeting HIF‐1α under non‐hypoxia/hypoxia conditions

Vascular endothelial growth factor (VEGF) is correlated with angiogenesis and early relapse of colorectal cancer (CRC). This study investigated the role of miR‐148a in the regulation of VEGF/angiogenesis and early relapse of CRC. We established a stable clone with miR‐148a expression in HCT116 and HT29 cell lines and created a hypoxic condition by using CoCl₂ to determine the underlying mechanism of miR‐148a. The effects of miR‐148a on the phosphoryl‐ERK (pERK)/hypoxia‐inducible factor‐1α (HIF‐1α)/VEGF pathway were evaluated through Western blotting and the inhibitory effect of miR‐148a on angiogenesis was demonstrated through a tube formation assay. Sixty‐three CRC tissues (28 early relapse and 35 non‐early relapse) were analysed to assess the relationship between miR‐148a and HIF‐1α/VEGF. The protein expression of pERK/HIF‐1α/VEGF in HCT116 and HT29 cells was significantly decreased by miR‐148a (all P < 0.05). The protein expression of VEGF/HIF‐1α was strongly inversely associated with the expression of miR‐148a in the 63 CRC tissue samples (all P < 0.05). Tube formation assay demonstrated that miR‐148a significantly obliterated angiogenesis. miR‐148a suppresses VEGF through down‐regulation of the pERK/HIF‐1α/VEGF pathway and might lead to the inhibition of angiogenesis; miR‐148a down‐regulation increased the early relapse rate of CRC. This demonstrates that miR‐148a is a potential diagnostic and therapeutic target.     

不同改良措施对松嫩平原重度盐碱地土壤结构与元素组成、杨树叶片光合及生长状况影响差异研究

重度盐碱地改良的长期效果尚存在争议,本研究在松嫩平原开展不同方式的杨树人工林栽植以实现土壤改良的目的,并对土壤内环境、杨树光合过程以及生长状别予以系统性研究。结果表明,重度盐碱地土壤结构内部结构分布更加均匀,疏松、垒结、空隙度、通气、透水能力、比表面积均得到改善;土壤中C和Fe元素含量平均分别增加29.7%、13.9%,Na元素含量平均减少82.4%,因此土壤胶粒凝聚土壤肥力增强,土壤盐碱化减缓;杨树光合速率、呼吸速率、高度、胸径、分枝数、分枝长、冠幅直径的增长率分别为328%~381%、98%~153%、23.8%、35.3%、160%、100%、73.5%,丘式“一”字沟改良后的根系生长最佳。该研究为松嫩平原退化盐碱地生物改良提供基础数据支持。     

The response of barley to rainfall and temperature in different tillage and crop rotation systems in semi‐arid conditions

Barley is a widespread crop of choice in the Spanish agricultural farming. A 7‐year field study was realised to examine the barley yield data. Weather conditions were analysed and taken into account when considering the influence of the tillage systems (TS) and previous crop on barley. In general, barley yield increased with tillage intensity; however the analysis of tiller‐count and thousand‐grain weight of barley did not present significant differences within the different TS. Barley monoculture presented lower yield than the barley in rotation with fallow or vetch, especially in those years characterised by a greater annual rainfall than average over the 7 years of study (290 mm). Also, we observed that the presence of weeds was strongly influenced by the combined effects of the environmental conditions, TS, and previous crop. It was observed that high rainfall during sowing period or shortly after had a high positive impact on production efficiency and yields. Unexpectedly, the study demonstrated positive correlation between high December temperatures and resulting barley yield. It would be useful to take into account these results when selecting the crop variety for conservation planning in Mediterranean areas.