Phosphate-Solubilizing Bacillus sp. Modulate Soil Exoenzyme Activities and Improve Wheat Growth.

Phosphorus (P) is a vital mineral nutrient in agriculture and its deficiency results in reduced growth, yield, and grain quality in cereals. Much of the applied P in agriculture becomes fixed in soils, limiting its accessibility to plants. Thus, investigating sustainable strategies to release fixed P resources and enhance plant uptake is crucial. This study explored how plant-associated bacteria employ phosphate solubilizing mechanisms to improve P availability. The growth patterns of four bacterial strains, namely Bacillus subtilis ZE15 and ZR3, along with Bacillus megaterium ZE32 and ZR19, were examined in Pikovskaya's broth culture with and without the addition of insoluble phosphorus (P). In the absence of P amendment, most strains reached a stationary growth phase by the fourth day. However, their responses diverged when exposed to P-amended media. Particularly, ZE15 demonstrated the highest P solubilization capability, achieving up to 130 µg mL-1 solubilization in vitro. All strains produced organic acids in Pikovskaya's broth culture. A comparison of the influence of Ca3(PO4)2 revealed significantly greater organic acid quantities in the presence of insoluble P. Notably, strain ZE15 exhibited the highest phosphate esterase activity (3.65 nmol g-1 dry matter), while strain ZE32 showed the highest ß-D glucosidase activity (2.81 nmol g-1 dry matter) in the presence of insoluble P. The ability of Bacillus species to solubilize P in combination with increased exoenzyme activity in the rhizosphere could be used in future studies to support P uptake through enhanced solubilization and mineralization.

Bacterial secondary metabolites: possible mechanism for weed suppression in wheat.

Chemical weed control is an effective method, but has proved hazardous for humans, environment, and soil biodiversity. Use of allelopathic bacteria may be more efficient and sustainable weed control measure. The bacterial inoculants have never been studied in context of their interaction with weed root exudates and precursor-dependent production of the natural phytotoxins (cyanide, cytolytic enzymes and auxin) by these strains to understand their weed suppression and wheat growth promotion abilities. Therefore, root exudates of Avena fatua, Phalaris minor, Rumex dentatus, and wheat were quantified and their role in microbial root colonization and secondary metabolite production, i.e., cyanide, cytolytic enzymes, phenolics, and elevated auxin concentration, was studied. The results depicted l-tryptophan and glycine as major contributors of elevated cyanide and elevated levels in weed rhizosphere by the studied Pseudomonas strains, through their higher root colonization ability in weeds as compared with wheat. Furthermore, the higher root colonization also enhanced p-coumaric acid (photosynthesis inhibitor by impairing cytochrome c oxidase activity in plants) and cytolytic enzyme (root cell wall degradation) concentration in weed rhizosphere. In conclusion, the differential root colonization of wheat and weeds by these strains is responsible for enhancing weed suppression (enhancing phytotoxic effect) and wheat growth promotion (lowering phytotoxic effect).

Determinants of Children's Fruit Intake in Teso South Sub-County, Kenya-A Multi-Phase Mixed Methods Study among Households with Children 0-8 Years of Age.

Fruits are micronutrient-rich sources which are often underrepresented in children's diets. More insights into the determinants of children's fruit consumption are needed to improve nutrition education in Teso South Sub-County, Kenya. A multiphase mixed method study was applied among 48 farm households with children 0-8 years of age. A market survey together with focus group discussions were used to design a formative research approach including qualitative and quantitative data collection methods. The unavailability of fruits and the inability to plant fruit trees in the homesteads were the main challenges to improve fruit consumption behaviour, although a number of different fruit species were available on the market or in households. Perceived shortage of fruits, financial constraints to purchase fruits and taste were important barriers. Fruits as snacks given between meals was perceived as helpful to satisfy children. The mean number of fruit trees in the homesteads was positively associated with fruit consumption. Field trials are needed to test how best fruit trees within home gardens and on farms can be included, acknowledging limited space and constraints of households with young children. This should be combined with nutrition education programs addressing perceptions about the social and nutrient value of fruits for children.

Can Occurrence and Distribution of Ground Beetles (Carabidae) Be Influenced by the Coffee Farming System in the Mount Elgon Region of Uganda?

The Mount Elgon region of Uganda has coffee farmlands distributed along the slopes of the mountain, in a mosaic of differing crop combinations, and semi-natural vegetation. Thus, there are parcels of varying microclimate that create disparities in occurrence of key insect functional groups. The study quantified the occurrence of Carabidae in 72 coffee farmlands categorized by altitude: low (1400-1499 m.a.s.l), mid (1500-1679 m.a.s.l), and high (1680-2100 m.a.s.l); and farming system: coffee monocrop, coffee+annual crops, coffee+banana, and coffee+banana+shade trees. The results revealed highly significant effects of altitude, farming systems, and the interaction of the two on occurrence of three Carabidae genera (Anisodactylus, Chlaenius, and Harpalus.). The abundance of Harpalus spp. was higher at lower altitudes in coffee monocropped farming systems; Anisodactylus spp. were more abundant at higher altitudes in coffee+annual crop systems; and Chlaenius spp. were highest in the coffee+banana+shade tree system at mid altitudes. The belowground microclimate parameters of soil moisture, pH, EC; and the aboveground diversity of semi-natural vegetation explained some of the differences in occurrence of the different Carabidae genera. This distinctiveness in preference of different genera in the same family hinders collective recommendations but looks to a more pragmatic strategy in nurturing diversity on a holistic scale.

Missing association between nutrient concentrations in leaves and edible parts of food crops - A neglected food security issue.

Crop nutrient deficiencies are determined based on leaf nutrient composition, and rarely on food composition. Consequently, it remains unclear whether leaf nutrients are useable to form conclusions on quality of produced foods. This study aimed to investigate the relationships between plant macro- (Mg, P, S, K, Ca) and micronutrient (Fe, Zn, Mn, Cu) concentrations of leaves and edible parts of three East African staple crops: Zea mays, Manihot esculenta, and Musa acuminata. Low phloem mobile nutrients Ca, Mn, Fe, Zn, and Cu showed the largest differences in correlations between leaves and edible parts. Perennial crops showed lower correlations between nutrient concentrations of leaves and edible parts than annuals. Leaves may provide information on plant health, however do not provide enough information to gauge both yields and food quality, particularly regarding micronutrients. Therefore, agricultural and nutritional scientists should harmonize methods to develop sustainable management options for increased food and nutrition security.

Soil and farm management effects on yield and nutrient concentrations of food crops in East Africa.

Crops that grow on soils with higher fertility often have higher yields and higher tissue nutrient concentrations. Whether this is the case for all crops, and which soil and management factors, or combinations mostly affect yields and food nutrient concentrations however, is poorly understood. Here, the main aim was to evaluate effects of soil and management factors on crop yields and food nutrient concentrations in (i) grain, fruit and tuber crops, and (ii) between high and low soil fertility areas. Total elemental concentrations of Mg, P, S, K, Ca, Fe, Zn, Mn and Cu were measured using a portable X-Ray Fluorescence Spectrometer (pXRF) in maize grain (Zea mays; Teso South, Kenya: n = 31; Kapchorwa, Uganda n = 30), cassava tuber (Manihot esculenta; Teso South: n = 27), and matooke fruit (Musa acuminata; Kapchorwa, n = 54). Soil properties measured were eCEC, total N and C, pH, texture, and total elemental content. Farm management variables (fertilisation, distance to household, and crop diversity) were collected. Canonical Correspondence Analyses (CCA) with permutation rank tests identified driving factors of alterations in nutrient concentrations. Maize grain had higher correlations with soil factors (CCA > 80%), than cassava tuber (76%) or matooke fruit (39%). In contrast, corresponding correlations to management factors were much lower (8-39%). The main soil properties affecting food nutrients were organic matter and texture. Surprisingly, pH did not play an important role. A positive association of crop diversity with nutrient concentration and yield in lower fertility areas was observed. Considering, food nutrient composition, apart from yield, as response variables in agronomic trials (e.g. fertilisation or soil improvement strategies), would contribute towards discounting the notion that crops growing on fertile soils always produce healthy and high quality foods.

Do we need more drought for better nutrition? The effect of precipitation on nutrient concentration in East African food crops.

Soil, inputs, and environmental factors such as weather control plant nutrient availability and nutrient content in food. Drought periods affect nutrient bioavailability. Nutrient transport within the plant and allocation of nutrients within organs of the plant is water dependent and therefore drought susceptible. This study compared Kapchorwa, Uganda and Teso South, Kenya that experienced drought during the second season in 2016. The main research questions were: (i) do droughts have an impact on the nutrient composition of food; (ii) is there a difference in nutrient concentrations in food based on their xylem or phloem mobility? Maize (Zea mays) grain (n = 62) and matooke (Musa acuminata) fruit samples (n = 90) in Kapchorwa, and maize grain (n = 61) and cassava (Manihot esculenta) tuber (n = 64) in Teso South were collected during a normal season (March-July) and drought season (October-December) in 2016. Crop samples were analysed using a pXRF for P, K, Ca, Mg, S, Fe, Mn, Cu, and Zn. The Standardized Precipitation Index (SPI) was calculated using TAMSAT database to compare drought intensities. The drought in Kapchorwa (SPI: -1.14 to -0.32) was severer and began 2 months prior to Teso South (SPI: 0.09 to 0.55). Nutrient concentration in Kapchorwa decreased significantly from normal to drought in both crops. In contrast, during the moderate drought in Teso South, nutrient concentrations increased significantly. Lacking nutrient phloem mobility is suggested to play a vital role in mobilisation of micronutrients (Fe, Mn, and Cu) as shown by their decreased concentration under severe drought in the yield. Total nutrients assimilated in crop samples were significantly higher in the normal than the drought for almost all samples. Micronutrients and yields during drought were strongly affected, leading to a double-burden for consumers through affected quantity and quality. Future research considerations should particularly include the focus on potential nutrient increases during mild drought.

Perspectives of Microbial Inoculation for Sustainable Development and Environmental Management.

How to sustainably feed a growing global population is a question still without an answer. Particularly farmers, to increase production, tend to apply more fertilizers and pesticides, a trend especially predominant in developing countries. Another challenge is that industrialization and other human activities produce pollutants, which accumulate in soils or aquatic environments, contaminating them. Not only is human well-being at risk, but also environmental health. Currently, recycling, land-filling, incineration and pyrolysis are being used to reduce the concentration of toxic pollutants from contaminated sites, but too have adverse effects on the environment, producing even more resistant and highly toxic intermediate compounds. Moreover, these methods are expensive, and are difficult to execute for soil, water, and air decontamination. Alternatively, green technologies are currently being developed to degrade toxic pollutants. This review provides an overview of current research on microbial inoculation as a way to either replace or reduce the use of agrochemicals and clean environments heavily affected by pollution. Microorganism-based inoculants that enhance nutrient uptake, promote crop growth, or protect plants from pests and diseases can replace agrochemicals in food production. Several examples of how biofertilizers and biopesticides enhance crop production are discussed. Plant roots can be colonized by a variety of favorable species and genera that promote plant growth. Microbial interventions can also be used to clean contaminated sites from accumulated pesticides, heavy metals, polyaromatic hydrocarbons, and other industrial effluents. The potential of and key processes used by microorganisms for sustainable development and environmental management are discussed in this review, followed by their future prospects.

Preliminary study on phosphate solubilizing Bacillus subtilis strain Q3 and Paenibacillus sp. strain Q6 for improving cotton growth under alkaline conditions.

BACKGROUND: Low phosphorus availability limits crop production in alkaline calcareous soils in semi-arid regions including Pakistan. Phosphate solubilizing bacteria may improve crop growth on alkaline calcareous soils due to their ability to enhance P availability. METHODS: Twenty rhizobacterial isolates (Q1-Q20) were isolated from rhizosphere of cotton and characterized for their growth promoting attributes in vitro. The selected phosphate solubilizing isolates were further screened for their ability to improve cotton growth under axenic conditions (jar trial). The phosphorus solubilization capacities of selected strains were quantified and these strains were identified through 16S rDNA sequencing. RESULTS: Isolates Q2, Q3, Q6, Q7, Q8, Q13 and Q14 were able to solubilize phosphate from insoluble sources. Most of these isolates also possessed other traits including catalase activity and ammonia production. The growth promotion assay showed that Q3 was significantly better than most of the other isolates followed by Q6. Maximum root colonization (4.34 × 106 cfu g-1) was observed in case of isolate Q6 followed by Q3. The phosphorus solubilization capacities of these strains were quantified, showing a maximum phosphorus solubilization by Q3 (optical density 2.605 ± 0.06) followed by the Q6 strain. The strain Q3 was identified as Bacillus subtilis (accession # KX788864) and Q6 as Paenibacillus sp. (accession # KX788865) through 16S rDNA sequencing. DISCUSSION: The bacterial isolates varied in their abilities for different growth promoting traits. The selected PGPR Bacillus subtilis strain Q3 and Paenibacillus sp. strain Q6 have multifarious growth promoting traits including ability to grow at higher EC and pH levels, and phosphorus solubilizing ability. These strains can efficiently colonize cotton roots under salt affected soils and help plants in phosphorus nutrition. It is concluded that both strains are potential candidates for promoting cotton growth under alkaline conditions, however further investigation is required to determine their potential for field application.

A 24-color metaphase-based radiation assay discriminates heterozygous BRCA2 mutation carriers from controls by chromosomal radiosensitivity.

Numerous allelic variants identified in the familial breast cancer and DNA repair genes BRCA1 and BRCA2 are of unknown impact on protein function or clinical relevance, referred to as unclassified variants (UCV). Lymphocytes from pathogenic BRCA1/2 mutation carriers exhibit an increased level of chromosomal damage after irradiation. We established a radiation assay for the discrimination of pathogenic BRCA2 variants versus controls based on the level of chromosomal damage upon irradiation (p < 0.001). As a consequence, lymphocytes from UCV carriers could be separated into two distinct groups with normal or diminished DNA double strand break repair capacity. Our results suggested that all five UCV tested were benign and that one family carried a putative mutation in an as yet undetected DNA-repair gene. Thus, our test may serve as a valuable tool that aids the classification of BRCA2 UCV, but very likely also of BRCA1 UCV or aberrations in other genes involved in the DNA-repair system.

Development of a three-dimensional in vitro model for longitudinal observation of cell behavior: monitoring by magnetic resonance imaging and optical imaging.

PURPOSE: The aim of this study is the development of a three-dimensional multicellular spheroid cell culture model for the longitudinal comparative and large-scale screening of cancer cell proliferation with noninvasive molecular imaging techniques under controlled and quantifiable conditions. PROCEDURES: The human glioblastoma cell line Gli36DeltaEGFR was genetically modified to constitutively express the fluorescence protein mCherry, and additionally labeled with iron oxide nanoparticles for high-field MRI detection. The proliferation of aggregates was longitudinally monitored with fluorescence imaging and correlated with aggregate size by light microscopy, while MRI measurements served localization in 3D space. Irradiation with gamma-rays was used to detect proliferational response. RESULTS: Cell proliferation in the stationary three-dimensional model can be observed over days with high accuracy. A linear relationship of fluorescence intensity with cell aggregate size was found, allowing absolute quantitation of cells in a wide range of cell amounts. Glioblastoma cells showed pronounced suppression of proliferation for several days following high-dose gamma-irradiation. CONCLUSIONS: Through the combination of two-dimensional optical imaging and 3D MRI, the position of individual cell aggregates and their corresponding light emission can be detected. This allows an exact quantification of cell proliferation, with a focus on very small cell amounts (below 100 cells) using high resolution noninvasive techniques as a well-controlled basis for further cell transplantation studies.

Characterization of a novel chronic photothrombotic ring stroke model in rats by magnetic resonance imaging, biochemical imaging, and histology.

A novel photothrombotic ring stroke model was characterized by multiparametric magnetic resonance imaging, imaging of cerebral blood flow (CBF), adenosine triphosphate (ATP), pH, and histology. Ischemia was initiated by transosseous irradiation of a predefined brain area intravenously perfused by the photosensitive dye erythrosin B in male Wistar rats. In the region of the primary ring-lesion, the phototoxic reaction caused necrosis reflected by low relative ATP levels (28 +/- 15%), alkalosis (pH: 7.35 +/- 0.50), and histologic evidence at 14 days after lesion induction. In the ring-encircled interior region (region-at-risk), spontaneous tissue reperfusion (relative CBF: 93 +/- 3%) enabled partial tissue preservation. This was demonstrated by a less impaired energy metabolism (ATP: 65 +/- 23%), normal pH (7.01 +/- 0.50), and still normal cellular structures shown by histologic staining. Analysis of the temporal characteristics within the region-at-risk revealed a slow continuous increase of the apparent diffusion coefficient of water (ADC) to 144 +/- 16% of control (14d) and an early vasogenic edema, reflected by an increase of the T2 relaxation time to 143 +/- 17% of control (2d). Both final ADC and T2 correlated well with the tissue pH within the region-at-risk, thus emphasizing the usefulness of this multiparametric noninvasive imaging approach.

Differences in clot preparation determine outcome of recombinant tissue plasminogen activator treatment in experimental thromboembolic stroke.

BACKGROUND AND PURPOSE: Thrombin-induced clots used in experimental thromboembolic stroke differ from clots forming spontaneously under clinical conditions. We investigated whether this difference influences the efficacy and outcome of thrombolytic treatment. METHODS: In rats, the middle cerebral artery was occluded by intracarotid injection of fibrin-rich clots, prepared either according to established methods by adding thrombin to freshly drawn arterial blood or by spontaneous coagulation. The mechanical properties of clots were determined in vitro by elasticity and plasticity tests. One hour after embolism, thrombolysis was started by intra-arterial application of recombinant tissue plasminogen activator (rtPA) (10 mg/kg). Treatment efficacy was monitored by MR measurements of blood perfusion, apparent diffusion coefficient (ADC), T2 relaxation time and blood-brain barrier permeability, and by pictorial measurements of ATP and pH. RESULTS: Thrombin-induced clots were classified as elastic, and spontaneously forming clots were classified as plastic. Middle cerebral artery embolism with thrombin-induced or spontaneously forming clots led to similar reduction of perfusion and ADC, but rtPA treatment efficacy differed greatly. In the spontaneously forming clot group, blood perfusion returned to or above control within 2 hours, ADC and ATP normalized, tissue pH exhibited alkalosis, and T2 and blood-brain barrier permeability did not change. In the thrombin-induced clot group, in contrast, blood reperfusion was delayed, ADC and ATP remained reduced, tissue pH was acidic, and edema developed, as reflected by increased T2 and blood-brain barrier permeability. CONCLUSIONS: rtPA-induced thrombolysis promotes rapid reperfusion and tissue recovery in animals embolized with spontaneously forming clots but not in those embolized with thrombin-induced clots. This difference is explained by the different mechanical and possibly molecular consequences of clot preparation and must be considered for the interpretation of thrombolysis experiments.

Thrombolytic treatment of clot embolism in rat: comparison of intra-arterial and intravenous application of recombinant tissue plasminogen activator.

BACKGROUND AND PURPOSE: We sought to test the hypothesis that intra-arterial recombinant tissue plasminogen activator (rtPA) treatment of thromboembolic stroke is more efficient than intravenous application. METHODS: Rats were embolized by intracarotid injection of autologous fibrin-rich blood clots. One hour later rtPA (10 mg/kg) was infused either intravenously (n=8) or intra-arterially (n=8). Control rats (n=8) received intra-arterial infusion of saline. Treatment was monitored by MR perfusion-weighted imaging and apparent diffusion coefficient (ADC) imaging, and outcome was evaluated by comparing incidence of hemorrhages and lesion volumes of ATP and pH. RESULTS: Clot embolism led to a decline of perfusion-weighted imaging signal intensity in the middle cerebral artery territory to <40% of control. Both intra-arterial and intravenous treatment significantly improved blood flow in cerebral cortex but not in caudate putamen. In untreated animals, ATP and pH lesion volumes were 510.3+/-94.5 and 438.6+/-39.2 mm(3) at 7 hours after clot embolism, respectively. Both intravenous and intra-arterial rtPA treatment produced hemorrhagic complications but reduced ATP lesion size to 296.2+/-136.1 and 370.3+/-103.7 mm(3) and reduced pH lesion size to 263.3+/-114.6 and 303.3+/-103.0 mm(3), respectively (P<0.05 for untreated versus treated rats; no difference between intravenous and intra-arterial treatment). ADC imaging revealed that lesion reduction was due to inhibition of infarct growth but not to reversal of primary injury. CONCLUSIONS: This study documents reduction of injury by rtPA treatment but does not reveal a difference between intra-arterial and intravenous application. Our data do not support an advantage of intra-arterial thrombolysis.

Magnetic resonance angiography of thromboembolic stroke in rats: indicator of recanalization probability and tissue survival after recombinant tissue plasminogen activator treatment.

Magnetic resonance angiography (MRA) was performed in a thromboembolic stroke model of the rat to characterize intracranial vessel occlusion patterns and to test its predictive power for tissue recovery after recombinant tissue plasminogen activator (rt-PA) treatment. After rt-PA-treated selective middle cerebral artery (MCA) occlusion, full recanalization was observed in two of three animals, whereas additional occlusion of the circle of Willis (CW) resulted in full vascular flow restitution in only one of six rats. Tissue reperfusion markedly lagged the onset of treatment, and the delay correlated with the pattern of vessel occlusion (20 to 23 minutes for selective MCA occlusion vs. 71 to 79 minutes for combined MCA/CW occlusion). In lateral cortex and striatum the apparent diffusion coefficient decreased to 78 +/- 15% of control after embolization, recovered to 80% to 85% after rt-PA treatment of selective MCA occlusion, but further declined to 66% to 69% after combined MCA/CW occlusion. Correspondingly, T2 relaxation time increased to 107% to 118% of control after selective MCA occlusion and to 112% to 124% after combined MCA/CW occlusion in these regions. The present investigation shows that MRA provides valuable information on the severity of thromboembolic stroke and has the power to predict, before the initiation of treatment, the functional tissue outcome after rt-PA-induced thrombolysis.