棉花在广西南宁的越冬耐冷性鉴定和遗传分析

在广西南宁对不同种质来源的棉花材料及其杂交后代进行越冬耐冷性鉴定,为多年生棉花耐冷育种提供基础材料。在开展最佳处理时间和处理温度筛选的基础上,采用5个耐冷生理生化指标(相对电导率、可溶性糖、可溶性蛋白、丙二醛和脯氨酸)和露地越冬指标综合鉴定63份材料的越冬耐冷性,并运用系统聚类的方法将其聚为4大类,即耐冷型23份、中度耐冷型19份、中度冷敏型9份和冷敏型12份,分别占供试材料的36.51%、30.16%、14.29%和19.05%。所有耐冷型材料均和多年生海岛棉种质有关,说明多年生海岛棉在越冬耐冷性育种上具有很高的利用价值。供试棉花材料越冬性的细胞质效应不显著,杂交后代的越冬性有向亲本的平均类型回归的趋势。     

Poly(3-hydroxybutyrate) production by <Emphasis Type="Italic">Halomonas boliviensis</Emphasis> in fed-batch culture

High poly(3-hydroxybutyrate) (PHB) content and volumetric productivity were achieved by fed-batch culture of Halomonas boliviensis using a defined medium. Initial shake flask cultivations in a minimal medium revealed that the growth of H. boliviensis was supported only when the medium was supplemented with aspartic acid, glycine, or glutamine. Addition of 0.1% (w/v) glutamine in the medium resulted in the highest cell dry weight (CDW; 3.9 g l⁻¹). Glutamine was replaced by the less expensive monosodium glutamate (MSG) in the medium without any notable change in the final cell density. Effect of initial concentrations of NH₄Cl and K₂HPO₄ on cell growth and PHB accumulation by H. boliviensis was then analyzed using a fed-batch fermentation system. The best conditions for PHB production by H. boliviensis were attained using 0.4% (w/v) NH₄Cl and 0.22% (w/v) K₂HPO₄ and adding MSG intermittently to the fermentor. Poly(3-hydroxybutyrate) content and CDW reached 90 wt.% and 23 g l⁻¹, respectively, after 18 h of cultivation. In order to increase CDW and PHB content, MSG, NH₄Cl, and K₂HPO₄ were initially fed to the fermentor to maintain their concentrations at 2%, 0.4%, and 0.22% (w/v), respectively, and subsequently their feed was suppressed. This resulted in a CDW of 44 g l⁻¹, PHB content of 81 wt.%, and PHB volumetric productivity of 1.1 g l⁻¹ h⁻¹.     

Phosphorus nutrition-mediated effects of arbuscular mycorrhiza on leaf morphology and carbon allocation in perennial ryegrass

The aim of this work was to disentangle phosphorus status-dependent and -independent effects of arbuscular mycorrhizal fungus (AMF) on leaf morphology and carbon allocation in perennial ryegrass (Lolium perenne). To this end, we assessed the P-response function of morphological components in mycorrhizal and nonmycorrhizal plants of similar size. AMF (Glomus hoi) stimulated relative P-uptake rate, decreased leaf mass per area (LMA), and increased shoot mass ratio at low P supply. Lower LMA was caused by both decreased tissue density and thickness. Variation in tissue density was almost entirely caused by variations in soluble C, while that in thickness involved structural changes. All effects of AMF were indistinguishable from those mediated by increases in relative P-uptake rate through higher P-supply rates. Thus the relationships between relative P-uptake rate, leaf morphology and C allocation were identical in mycorrhizal and nonmycorrhizal plants. No evidence was found for AMF effects not mediated by changes in plant P status.     

Altering the balance between bacterial production and protistan bacterivory triggers shifts in freshwater bacterial community composition

Bacterivorous protists are known to induce changes in bacterial community composition (BCC). We hypothesized that changes in BCC could be related quantitatively to a measure of grazing: the ratio of bacterial mortality to growth rate. To test this hypothesis, we analyzed time-course changes in BCC, protistan grazing rate, and bacterial production from 3 in situ studies conducted in a freshwater reservoir and three laboratory studies. In the field experiments, samples were manipulated to yield different levels of protistan bacterivory and incubated in dialysis bags. Laboratory investigations were continuous cultivation studies in which different bacterivorous protists were added to bacterial communities. BCC was assessed using 4–6 different rRNA-targeted oligonucleotide probes for community analysis. Change in BCC (Δ BCC) was estimated as the sum of changes in the proportions of the two phylogenetic groups that showed the largest shifts. Analysis of a set of 22 estimates of shifts in the ratio of grazing to production rate over periods of 48–72 h and Δ BCC showed that Δ BCC was positively and tightly correlated (r ² = 0.784) with shifts in the ratio of grazing mortality to cell production. While the nature of a shift in BCC is unpredictable, the magnitude of the change can be related to changes in the balance between bacterial production and protistan grazing. This revised version was published online in August 2006 with corrections to the Cover Date.     

Protein enrichment of sweet potato residue by solid-state cultivation with mono- and co-cultures of amylolytic fungi

The degree of protein enrichment of sweet potato residue by different amylolytic moulds in solid-state cultivation was much greater than that obtained using amylolytic yeasts. The optimum initial moisture content for protein enrichment was about 65% (w/w). Adding nitrogen sources to the culture twice (at the start of the incubation and after 24 h) considerably improved the final protein content. A co-culture of amylolytic mycelial fungi yielded a product with 32% (w/w) crude protein after 4 days' incubation at 30°C. In a column reactor, the highest temperatures reached were 42°C and 40°C and the minimum O₂ concentrations were 1.5% and 2.5% of full saturation in the central and bottom layers, respectively.     

Industrial enzymes--developments in production and application

The utilization of gene technology and of new production technologies have made industrial enzymes with improved properties or better cost performance available. This has in turn opened important new areas of enzyme applications. The benefits to the customers are considerable: cost savings in the application process, improved product quality, and in most cases also a significantly reduced impact on the environment.

Gene technology offers several benefits to the enzyme industry. This technology enables the use of safe, well-documented host organisms easy to cultivate, the microbial production of enzymes of animal and plant origin, the realization of enhanced efficiency and high product purity, and also the production of enzymes with improved stability and activity.

Developments in production technology include advanced control methods, the use of expert systems, and the application of large-scale crystallization.

As case stories the development of a lipase and of a cellulase is described. The effect on environment of enzyme application and production is discussed.     

Noninvasive online biomass detector system for cultivation in shake flasks

A novel online sensor system for noninvasive and continuous monitoring of cell growth in shake flasks is described. The measurement principle is based on turbidity measurement by detecting 180°‐scattered light and correlation to OD by nonlinear calibration models. The sensor system was integrated into a commercial shaking tablar to read out turbidity from below the shake flasks bottom. The system was evaluated with two model microorganisms, Escherichia coli K12 as prokaryotic and Saccharomyces cerevisiae as eukaryotic model. The sensor allowed an accurate monitoring of turbidity and correlation with OD₆₀₀ ≤ 30. The determination of online OD showed relative errors of about 7.5% for E. coli K12 and 12% for S. cerevisiae. This matches the errors of the laborious offline OD and thus facilitates to overcome the drawbacks of the classical method as risk of contamination and decreasing volumes through sampling. One major challenge was to ensure a defined, nonvarying measurement zone as the rotating suspension in the shake flask forms a liquid sickle which circulates round the flasks inner bottom wall. The resulting alteration of liquid height above the sensor could be compensated by integration of an acceleration sensor into the tablar to synchronize the sensor triggering.     

人工栽培猴头菌多糖提取工艺及抑菌作用研究

研究人工栽培猴头菌多糖最佳提取工艺和抑菌作用。采用正交试验法研究人工栽培猴头菌多糖的提取工艺,经透析、除蛋白、真空干燥后,采用DEAE-52阴离子交换纤维素进行分离纯化,Nacl分段梯度洗脱得到纯化的人工栽培猴头菌多糖0.2M组分,采用滤纸片扩散法研究人工栽培猴头菌多糖的抑菌作用、pH值对抑菌作用的影响和最小抑菌浓度(MIC)。结果表明:人工栽培猴头菌多糖的最佳提取工艺为浸提温度60℃、提取时间4 h、料液比1∶25,人工栽培猴头菌多糖对大肠杆菌有一定的抑制作用,对金黄色葡萄球菌、枯草芽孢杆菌、沙门氏菌几乎没有抑菌作用。     

The influence of cultivation methods on Shewanella oneidensis physiology and proteome expression

High-throughput analyses that are central to microbial systems biology and ecophysiology research benefit from highly homogeneous and physiologically well-defined cell cultures. While attention has focused on the technical variation associated with high-throughput technologies, biological variation introduced as a function of cell cultivation methods has been largely overlooked. This study evaluated the impact of cultivation methods, controlled batch or continuous culture in bioreactors versus shake flasks, on the reproducibility of global proteome measurements in Shewanella oneidensis MR-1. Variability in dissolved oxygen concentration and consumption rate, metabolite profiles, and proteome was greater in shake flask than controlled batch or chemostat cultures. Proteins indicative of suboxic and anaerobic growth (e.g., fumarate reductase and decaheme c-type cytochromes) were more abundant in cells from shake flasks compared to bioreactor cultures, a finding consistent with data demonstrating that “aerobic” flask cultures were O₂ deficient due to poor mass transfer kinetics. The work described herein establishes the necessity of controlled cultivation for ensuring highly reproducible and homogenous microbial cultures. By decreasing cell to cell variability, higher quality samples will allow for the interpretive accuracy necessary for drawing conclusions relevant to microbial systems biology research.     

几种草坪草的引种栽培试验研究

通过对引种栽培的8种草坪草的物候期、覆盖度、再生速度、品质特性及抗逆性等方面进行分析研究和综合评价,筛选出适合北方温带环境条件下栽培的几种优良草坪草品种——新哥来德(Poa pratensis cv．Nugtade)、枪手股(P.pratensis cv．BlueChip)、午夜(P．pratensis cv．Midnight)、帕特(Agrostis tenuis cv．Putter)、贝克(碧西)(Festuca arundinacea cv．Plxie)等。对陕西关中草坪草的引种和适地栽植提供一定的理论依据。