Sorghum Insect Problems and Management

Sorghum (Sorghum bicolor) has high levels of starch,sugar,and fiber and is one of the most important energy crops in the world.Insect damage is one of the challenges that impacts sorghum biomass production.There are at least 150 insect species that can infest sorghum varieties worldwide.These insects can complete several generations within a growing season,they target various parts of sorghum plants at developmental stages,and they cause significant biomass losses.Genetic research has revealed the existence...     

Isolation and investigation of anaerobic microorganisms involved in methanol transformation in an underground gas storage facility

High methanol and acetate concentrations (up to 12 and 14 g l⁻¹, respectively) were found in water samples collected at different objects of the North Stavropol underground gas storage facility (UGSF), and significant seasonal variations in the content of these compounds were revealed. The dominant anaerobic microorganisms isolated from these samples during the study belonged to acetogens, methanogens, and sulfate reducers. The results of 16S rRNA gene sequencing and analysis of the physiological properties showed that the isolates were close to the species of Eubacterium limosum, Sporomusa sphaeroides, Methanosarcina barkeri, Methanobacterium formicicum, and Desulfovibrio desulfuricans. The isolated organisms, except for Methanobacterium formicicum, were capable of methylotrophic growth. All strains were characterized by resistance to high methanol concentrations (up to 40–50 g l⁻¹). Their other energy substrate was hydrogen. The combination of the growth characteristics of these strains (pH, temperature, and salinity ranges) was shown to correspond to the ecological situation observed in the UGSF. The results of investigation of the isolated strains suggest that organic acids (acetate, butyrate) found in high concentrations in the initial samples are metabolic products of the revealed acetogens. Based on the established biological peculiarities of the isolated strains of methanogens, acetogens, and sulfate-reducing bacteria, these microorganisms may be considered as the main agents of anaerobic transformation of methanol and some other organic and inorganic compounds in UGSFs.     

A microbiological study of an underground gas storage in the process of gas extraction

The numbers of microorganisms belonging to ecologically significant groups and the rates of terminal microbial processes of sulfate reduction and methanogenesis were determined in the liquid phase of an underground gas storage (UGS) in the period of gas extraction. The total number of microorganisms in water samples from the operation and injection wells reached 2.1 x 10(6) cells/ml. Aerobic organotrophs (including hydrocarbon- and oil-oxidizing ones) and various anaerobic microorganisms (fermenting bacteria, methanogens, acetogens, sulfate-, nitrate-, and iron-reducing bacteria) were constituent parts of the community. The radioisotopic method showed that, in all the UGS units, the terminal stages of organic matter decomposition included sulfate reduction and methanogenesis, with the maximal rate of these processes recorded in the aqueous phase of above-ground technological equipment which the gas enters from the operation wells. A comparative analysis by these parameters of different anaerobic ecotopes, including natural hydrocarbon fields, allows us to assess the rate of these processes in the UGS as high throughout the annual cycle of its operation. The data obtained indicate the existence in the UGS of a bacterial community that is unique in its diversity and metabolic capacities and able to make a certain contribution to the geochemistry of organic and inorganic compounds in the natural and technogenic ecosystem of the UGS and thus influence the industrial gas composition.     

Ionogenic groups in the active site of lysostaphin. Kinetic and thermodynamic data compared with X-ray crystallographic data

The active site of lysostaphin is shown to contain a residue of glutamic acid. As judged by a pK value of 9.2 (with pentaglycine bridges in peptidoglycan of staphylococci as a substrate), another ionogenic residue could be the epsilon-amino group of a lysine. However, the pH value near a negatively charged cell is supposed to be strongly shifted to acidity as compared to the pH of the solution volume. This shifts the enzyme pH dependence curve in solution to alkalinity. Therefore, the other group might be histidine, which is consistent with the X-ray crystallographic data. A similar shift is likely to occur for lysozyme in the case of Micrococcus lysodeikticus cells. Determination of pK of ionogenic groups in the active sites of alkaline enzymes responsible for lysis of negatively charged bacterial cells gives their apparent values because the "pericellular" and "voluminous" values of pH are not coincident.     

The properties of hydrocarbon-oxidizing bacteria isolated from the oilfields of Tatarstan, western Siberia, and Vietnam

Eleven strains of hydrocarbon-oxidizing bacteria, isolated from oilfields and representing the genera Rhodococcus, Gordonia, Dietzia, and Pseudomonas, were characterized as mesophiles and neutrophiles. Rhodococci were halotolerant microorganisms growing in a media containing up to 15% NaCl. All the strains oxidized n-alkanes of crude oil. An influence of the cultivation temperatures (28 or 45°C) and organic supplements on the degradation of C₁₂-C₃₀ n-alkanes in oxidized oil by two bacterial strains of the genus Pseudomonas was shown. The introduction of acetate, propionate, butyrate, ethanol, and sucrose led mainly to decreased oxidation of petroleum paraffins. At certain cultivation temperatures, the addition of volatile fatty acid salts increased the content of certain n-alkanes in oxidized oil as compared to crude oil.     

桃儿七光合生理特性的地理差异研究

对中国由南向北5个种源地桃儿七(Sinopodophyllum hexandrum)的光合生理生态特性进行了研究.结果表明:(1)北部宁夏六盘山地区植株的光饱和点(LSP)和光补偿点(LCP)最高,表观光量子效率(AQY)、瞬时光能利用效率(ILUE)和最大光合速率(Pmax)最低,光合能力最差;最南部云南纳帕海植株的LSP和LCP很低,但因其AQY和ILUE最高,故其Pmax最大,强光下的光合能力最高.(2)最南部云南纳帕海和最北部甘肃兴隆山个体的羧化效率(CE)最高,且CO2补偿点(CCP)较低,因此CO2利用率较高;而较南部四川刷经寺个体的CE最低,且CCP最高,故CO2利用效率最低.(3)各种源植株叶片的叶绿素总量及叶绿素a含量无显著差异,而不同地区个体的Chla/Chlb值差异显著,最北部甘肃兴隆山植株的Chla/Chlb值最大,而南部四川刷经寺的Chla/Chlb值最小.(4)各种源地植株的水分利用效率(WUE)和蒸腾速率(Tr)对光量子通量密度(PFD)与CO2浓度的响应过程也表现出显著的地理分异.总的来看,桃儿七是一种喜光但又较耐阴植物,但不同分布区桃儿七的光合生理生态特征已经出现了较显著的地理分化.     

A型肉毒毒素轻链基因的克隆及其结构分析

以献报道的A型肉毒毒素基因全序列为标准,设计并合成一对引物,自肉毒梭菌基因组中扩增出肉毒毒素轻链基因片段,并将扩增产物与pGEM—T载体在体外连接,构建测序重组质粒,进行测序和基因结构分析。PCR扩增获得了产物为1 364bp的DNA片段,测序结果与DNA数据库对照检索分析证明,此基因片段与GenBank中的A型肉毒毒素LC基因的一致性达99．9％以上,可以认为克隆的基因为A型肉毒毒素LC基因。