Combined amino acids modulation with H2O2 stress for glutathione overproduction in Candida utilis

Strategies of amino acids addition coupled with H2O2 stresses were developed for glutathione (GSH) overproduction in high cell density (HCD) cultivation of Candida utilis. Based on the fact that glycine shows two functions of promoting cells growth as well as GSH production, precursor amino acids modulations of feeding glycine at 4 mmol/l/h at exponential phase and adding precursor amino acids (glutamic acid 42 mmol/l, glycine 40 mmol/l, and cysteine 36 mmol/) at stationary phase were conducted. As a result, cell density reached 114.8 g/l at 45 h and glutathione yield of 2136 mg/l was achieved at 60 h, which was 12.5 and 90.2% higher than the control, respectively. Furthermore, the novel strategies of amino acids modulation combined with H2O2 additions (24 mmol/l at 21 h, 26 mmol/l at 29 h, 28 mmol/l at 37 h and 30 mmol/l at 45 h) were adopted to maximize glutathione production. Final glutathione yield reached 2448 mg/l after 60 h cultivation, suggesting the strategies developed as being feasible for GSH overproduction. Keywords: Amino acids, glutathione (GSH), high cell density (HCD) cultivation, Candida utilis, H2O2 stressesAfrican Journal of Biotechnology Vol. 9(33), pp. 5399-5406, 16 August, 201

Effects of Topography on Tree Community Structure in a Deciduous Broad-Leaved Forest in North-Central China

Topography strongly influences the compositional structure of tree communities and plays a fundamental role in classifying habitats. Here, data of topography and 16 dominant tree species abundance were collected in a fully mapped 25-ha forest plot in the Qinling Mountains of north-central China. Multivariate regression trees (MRT) were used to categorize the habitats, and habitat associations were examined using the torus-translation test. The relative contributions of topographic and spatial variables to the total community structure were also examined by variation partitioning. The results showed the inconsistency in association of species with habitats across life stages with a few exceptions. Topographic variables [a + b] explained 11% and 19% of total variance at adult and juvenile stage, respectively. In contrast, spatial factors alone [c] explained more variation than topographic factors, revealing strong seed dispersal limitation in species composition in the 25-ha forest plot. Thus, the inconsistent associations of species and habitats coupled with high portion of variation of species composition explained by topographic and spatial factors might suggest that niche process and dispersal limitation had potential influences on species assemblage in the deciduous broad-leaved forest in north-central China

A Newly Acidophilic Bacterium Acidomyces acidothermus Was Isolated to Efficiently Bioleach Copper from Waste Printed Circuit Boards (WPCBs)

An acidophilic metal-resistant bacterial strain, Acidomyces acidothermus (A. acidothermus), was isolated and identified by morphology, physiology, biochemistry, and 16S rDNA. A. acidothermus culture conditions were optimized by response surface methodology (RSM). Results showed that with a temperature of 40 °C, a pH of 3 in a 9k medium, and a rotation speed of 140 r/min, the copper leaching rate reached the highest value of 39.8%. Furthermore, SEM images and a heatmap of differential metabolites indicated that A. acidothermus adsorbed on the surface of WPCBs and extracellular polymeric substances (EPS), mainly D-glucuronic acid, were secreted, suggesting the highly efficient mechanism of copper recovery from WPCBs

Effects of UAV-LiDAR and Photogrammetric Point Density on Tea Plucking Area Identification

High-cost data collection and processing are challenges for UAV LiDAR (light detection and ranging) mounted on unmanned aerial vehicles in crop monitoring. Reducing the point density can lower data collection costs and increase efficiency but may lead to a loss in mapping accuracy. It is necessary to determine the appropriate point cloud density for tea plucking area identification to maximize the cost–benefits. This study evaluated the performance of different LiDAR and photogrammetric point density data when mapping the tea plucking area in the Huashan Tea Garden, Wuhan City, China. The object-based metrics derived from UAV point clouds were used to classify tea plantations with the extreme learning machine (ELM) and random forest (RF) algorithms. The results indicated that the performance of different LiDAR point density data, from 0.25 (1%) to 25.44 pts/m2 (100%), changed obviously (overall classification accuracies: 90.65–94.39% for RF and 89.78–93.44% for ELM). For photogrammetric data, the point density was found to have little effect on the classification accuracy, with 10% of the initial point density (2.46 pts/m2), a similar accuracy level was obtained (difference of approximately 1%). LiDAR point cloud density had a significant influence on the DTM accuracy, with the RMSE for DTMs ranging from 0.060 to 2.253 m, while the photogrammetric point cloud density had a limited effect on the DTM accuracy, with the RMSE ranging from 0.256 to 0.477 m due to the high proportion of ground points in the photogrammetric point clouds. Moreover, important features for identifying the tea plucking area were summarized for the first time using a recursive feature elimination method and a novel hierarchical clustering-correlation method. The resultant architecture diagram can indicate the specific role of each feature/group in identifying the tea plucking area and could be used in other studies to prepare candidate features. This study demonstrates that low UAV point density data, such as 2.55 pts/m2 (10%), as used in this study, might be suitable for conducting finer-scale tea plucking area mapping without compromising the accuracy

Effects of UAV-LiDAR and Photogrammetric Point Density on Tea Plucking Area Identification

High-cost data collection and processing are challenges for UAV LiDAR (light detection and ranging) mounted on unmanned aerial vehicles in crop monitoring. Reducing the point density can lower data collection costs and increase efficiency but may lead to a loss in mapping accuracy. It is necessary to determine the appropriate point cloud density for tea plucking area identification to maximize the cost–benefits. This study evaluated the performance of different LiDAR and photogrammetric point density data when mapping the tea plucking area in the Huashan Tea Garden, Wuhan City, China. The object-based metrics derived from UAV point clouds were used to classify tea plantations with the extreme learning machine (ELM) and random forest (RF) algorithms. The results indicated that the performance of different LiDAR point density data, from 0.25 (1%) to 25.44 pts/m2 (100%), changed obviously (overall classification accuracies: 90.65–94.39% for RF and 89.78–93.44% for ELM). For photogrammetric data, the point density was found to have little effect on the classification accuracy, with 10% of the initial point density (2.46 pts/m2), a similar accuracy level was obtained (difference of approximately 1%). LiDAR point cloud density had a significant influence on the DTM accuracy, with the RMSE for DTMs ranging from 0.060 to 2.253 m, while the photogrammetric point cloud density had a limited effect on the DTM accuracy, with the RMSE ranging from 0.256 to 0.477 m due to the high proportion of ground points in the photogrammetric point clouds. Moreover, important features for identifying the tea plucking area were summarized for the first time using a recursive feature elimination method and a novel hierarchical clustering-correlation method. The resultant architecture diagram can indicate the specific role of each feature/group in identifying the tea plucking area and could be used in other studies to prepare candidate features. This study demonstrates that low UAV point density data, such as 2.55 pts/m2 (10%), as used in this study, might be suitable for conducting finer-scale tea plucking area mapping without compromising the accuracy

Iodine-assisted solid-state synthesis and characterization of nanocrystalline zirconium diboride nanosheets

A solid-state route was developed to prepare zirconium diboride nanosheets with the dimension of about 500 nm and thickness of about 20 nm from zirconium dioxide, iodine and sodium borohydride at 700 °C in an autoclave reactor. The obtained ZrB₂ product was investigated by X-ray diffraction, scanning electron microscope and transmission electron microscopy. The obtained product was also studied by thermogravimetric analysis. It had good thermal stability and oxidation resistance below 400 °C in air. Furthermore, the possible formation mechanism of ZrB₂ was also discussed.Розроблено твердотільний напрямок отримання наношарів дибориду цирконію розміром ~ 500 нм і товщиною ~ 20 нм з діоксиду цирконію, йоду та боргідриду натрію при 700 °С в автоклавному реакторі. Отриманий продукт ZrB₂ досліджували рентгенівською дифракцією, скануючим електронним мікроскопом і трансмісійною електронною мікроскопією. Отриманий продукт також вивчали термогравіметричним аналізом. Він мав гарну термостійкість і стійкість до окиснення нижче 400 °C на повітрі. Крім того, обговорено також можливий механізм утворення ZrB₂.Разработан твердотельный путь получения нанослоев диборида циркония размером ~ 500 нм и толщиной ~ 20 нм из диоксида циркония, йода и боргидрида натрия при 700 °С в автоклавной реакторе. Полученный продукт ZrB₂ исследовали рентгеновской дифракцией, сканирующим электронным микроскопом и трансмиссионной электронной микроскопией. Полученный продукт также изучали термогравиметрическим анализом. Он имел хорошую термостойкость и устойчивость к окислению ниже 400 °C на воздухе. Кроме того, обсуждали также возможный механизм образования ZrB₂

Disparity in elevational shifts of upper species limits in response to recent climate warming in the Qinling Mountains, North-central China

Examinations of upper elevational distribution limits of tree species can provide indications of how subalpine vegetation responds to the ongoing climate warming. Dynamics and functional mechanisms of elevational treelines are reasonably well understood, while explanations for tree species-specific upper elevational distribution limits below the treeline still remain unclear. In this study, we used a state-of-the-art dendroecological approach to reconstruct long-term changes of species-specific upper elevational distribution limits of different plant functional type (i.e., light-demanding deciduous coniferous larch at treeline, shade-tolerant evergreen coniferous fir and shade-intolerant deciduous broad-leaved birch below treeline) along elevational gradients in the Qinling Mountains of north-central China. Over the past three centuries, all the upper species limits shifted upslope as a response to climate warming. However, the warming-induced upslope migrations showed substantial differences, displaying the maximum upward shift of larch with an average elevation of 24.7 m during the past century, while only a slight advance of the non-treeline tree species. The disparity in elevational advance of upper species limits might be attributable to the presence of interspecific competition, showing that the non-treeline tree species experienced intermediate interspecific competition while the treeline tree species experienced no interspecific competition.Thus, our findings suggested that in addition to climate warming, biotic interaction may contribute much to shaping the species-specific upper limit dynamics. This study not only enhanced mechanistic understanding of long-term species-specific upper elevational distribution limit changes, but also highlighted the jointly effects of rising temperatures and species interactions on subalpine vegetation dynamics. (C) 2019 Elsevier B.V. All rights reserved

Climate warming could free cold-adapted trees from C-conservative allocation strategy of storage over growth

<p>Carbon allocation has been fundamental for long-lived trees to survive cold stress at their upper elevation range limit. Although carbon allocation between NSC (non-structural carbohydrate) storage and structural growth is well-documented, it still remains unclear how ongoing climate warming influences these processes, particularly whether these two processes will shift in parallel or respond divergently to warming. Using a combination of an in situ downward-transplant warming experiment and an ex situ chamber warming treatment, we investigated how subalpine fir trees at their upper elevation limit coordinated carbon allocation priority among different sinks (e.g., NSC storage and structural growth) at whole-tree level in response to elevated temperature. We found that transplanted individuals from the upper elevation limit to lower elevations generally induced an increase in specific leaf area, but there was no detected evidence of warming effect on leaf-level saturated photosynthetic rates. Additionally, our results challenged the expectation that climate warming will accelerate structural carbon accumulation while maintaining NSC constant. Instead, individuals favored allocating available carbon to NSC storage over structural growth after one year of warming, despite the amplification in total biomass encouraged by both in situ and ex situ experimental warming. Unexpectedly, continued warming drove a regime shift in carbon allocation priority, which was manifested in the increase of NSC storage in synchrony to structural growth enhancement. These findings imply that climate warming would release trees at their cold edge from C-conservative allocation strategy of storage over structural growth. Thus, understanding the strategical regulation of the carbon allocation priority and the distinctive function of carbon sink components is of great implication for predicting tree fate in the future climate warming.</p><p>Funding provided by: National Natural Science Foundation of China<br>Crossref Funder Registry ID: https://ror.org/01h0zpd94<br>Award Number: 31971491</p><p>Funding provided by: National Natural Science Foundation of China<br>Crossref Funder Registry ID: https://ror.org/01h0zpd94<br>Award Number: 32201371</p&gt

Chemical synthesis of niobium diboride nanosheets by a solid-state reaction route

A new process was developed to synthesize niobium diboride (NbB₂) nanosheets with the dimension of about 500 nm and thickness of about 10 nm by using metal niobium, iodine and sodium borohydride as starting materials in an stainless steel autoclave at 700 °C. Iodine was used to facilitate the exothermic reaction between metal niobium and sodium borohydride and the formation of NbB₂. X-ray powder diffraction pattern indicated that the obtained product is hexagonal phase NbB₂ with the calculated lattice constants a = 110 Å and c = 3.2929 Å. The obtained product was also studied by thermogravimetric analysis. It had good oxidation resistance below 400 °C in air.Розроблено новий процес синтезу наношарів дибориду ніобію (NbB₂) розмірами ~ 500 нм і товщиною ~ 10 нм з використанням металічного ніобію, йоду і боргідриду натрію як вихідних матеріалів у автоклаві з нержавіючої сталі при 700 °С. Йод використовували для полегшення екзотермічної реакції між металічним ніобієм і боргідридом натрію для утворення наношарів NbB₂. Рентгенограма порошку показала, що отриманий продукт є гексагональною фазою NbB₂ з розрахованими константами решітки a = 110 Å і c = 3,2929 Å. Отриманий продукт також вивчали термогравіметричним аналізом. Він мав гарну стійкість до окиснення в повітрі за температури нижче 400 °C .Разработан новый процесс синтеза нанослоев диборида ниобия (NbB₂2) размерами ~ 500 нм и толщиной ~ 10 нм с использованием металлического ниобия, йода и боргидрида натрия в качестве исходных материалов в автоклаве из нержавеющей стали при 700 °C. Йод использовали для облегчения экзотермической реакции между боргидридом натрия и ниобием для получения нанослоев NbB₂. Рентгенограмма порошка показала, что полученный продукт представляет собой гексагональную фазу NbB₂ с рассчитанными постоянными решетки a = 110 Å и c = 3,2929 Å. Полученный продукт также изучали с помощью термогравиметрического анализа. Он имел хорошую стойкость к окислению на воздухе при температуре ниже 400 °C