Control of pore geometry in soil microcosms and its effect on the growth and spread of <i>Pseudomonas </i>and <i>Bacillus</i> sp.

Simplified experimental systems, often referred to as microcosms, have played a central role in the development of modern ecological thinking on issues ranging from competitive exclusion to examination of spatial resources and competition mechanisms, with important model-driven insights to the field. It is widely recognized that soil architecture is the key driver of biological and physical processes underpinning ecosystem services, and the role of soil architecture and soil physical conditions is receiving growing interest. The difficulty to capture the architectural heterogeneity in microcosms means that we typically disrupt physical architecture when collecting soils. We then use surrogate measures of soil architecture such as aggregate size distribution and bulk-density, in an attempt to recreate conditions encountered in the field. These bulk-measures are too crude and do not describe the heterogeneity at microscopic scales where microorganisms operate. In the current paper we therefore ask the following questions: (i) To what extent can we control the pore geometry at microscopic scales in microcosm studies through manipulation of common variables such as density and aggregate size?; (ii) What is the effect of pore geometry on the growth and spread dynamics of bacteria following introduction into soil? To answer these questions, we focus on Pseudomonas sp. and Bacillus sp. We study the growth of populations introduced in replicated microcosms packed at densities ranging from 1.2 – 1.6 g cm-3, as well as packed with different aggregate sizes at identical bulk-density. We use X-ray CT and show how pore geometrical properties at microbial scales such as connectivity and solid-pore interface area, are affected by the way we prepare microcosms. At a bulk-density of 1.6 g cm-3 the average number of Pseudomonas was 63% lower than at a bulk-density of 1.3 g cm-3. For Bacillus this reduction was 66 %. Depending on the physical conditions, bacteria in half the samples took between 1.62 and 9.22 days to spread 1.5 cm. Bacillus did spread faster than Pseudomonas and both did spread faster at a lower bulk-density. Our results highlight the importance that soil physical properties be considered in greater detail in soil microbiological studies than is currently the case

Combination of techniques to quantify the distribution of bacteria in their soil microhabitats at different spatial scales

To address a number of issues of great societal concern at the moment, like the sequestration of carbon, information is direly needed about interactions between soil architecture and microbial dynamics. Unfortunately, soils are extremely complex, heterogeneous systems comprising highly variable and dynamic micro-habitats that have significant impacts on the growth and activity of inhabiting microbiota. Data remain scarce on the influence of soil physical parameters characterizing the pore space on the distribution and diversity of bacteria. In this context, the objective of the research described in this article was to develop a method where X-ray microtomography, to characterize the soil architecture, is combined with fluorescence microscopy to visualize and quantify bacterial distributions in resin-impregnated soil sections. The influence of pore geometry (at a resolution of 13.4 μm) on the distribution of Pseudomonas fluorescens was analysed at macro- (5.2 mm × 5.2 mm), meso- (1 mm × 1 mm) and microscales (0.2 mm × 0.2 mm) based on an experimental setup simulating different soil architectures. The cell density of P. fluorescens was 5.59 x 107(SE 2.6 x 106) cells g−1 soil in 1–2 mm and 5.84 x 107(SE 2.4 x 106) cells g−1 in 2–4 mm size aggregates soil. Solid-pore interfaces influenced bacterial distribution at micro- and macroscale, whereas the effect of soil porosity on bacterial distribution varied according to three observation scales in different soil architectures. The influence of soil porosity on the distribution of bacteria in different soil architectures was observed mainly at the macroscale, relative to micro- and mesoscales. Experimental data suggest that the effect of pore geometry on the distribution of bacteria varied with the spatial scale, thus highlighting the need to consider an “appropriate spatial scale” to understand the factors that regulate the distribution of microbial communities in soils. The results obtained to date also indicate that the proposed method is a significant step towards a full mechanistic understanding of microbial dynamics in structured soils

Influence of soil structure on the spread of <i>Pseudomonas fluorescens</i> in soil at microscale

For over a half a century, researchers have been aware of the fact that the physical and chemical characteristics of microenvironments in soils strongly influence the activity, growth, and metabolism of microorganisms. However, many aspects of the effect of soil physical characteristics, such as the pore geometry, remain poorly understood. Therefore, the objective of the present research was to determine the influence of soil pore characteristics on the spread of bacteria, observed at the scale relevant to microbes. Pseudomonas fluorescens was introduced in columns filled with 1–2 mm soil aggregates, packed at different bulk densities.. Soil microcosms were scanned at 10.87 μm voxel resolution using X‐ray computed tomography (CT) to characterize the geometry of pores. Thin sections were prepared to determine the spread and colonization of bacteria. The results showed that average bacterial cell density was 174 cells mm−2 in soil with bulk density of 1.3 g cm−3 and 99 cells mm−2 in soil with bulk density of 1.5 g cm−3. Soil porosity and solid‐pore interfaces influence the spread of bacteria and their colonization of the pore space at lower bulk density, resulting in relatively higher bacterial densities in larger pore spaces. The study also demonstrates that thin sectioning of resin impregnated soil samples can be combined with X‐ray CT to visualize bacterial colonization of a 3D pore volume. This research therefore represents a significant step towards understanding how environmental change and soil management impact bacterial diversity in soils

In Vitro Antiproliferative Efficacy, Antioxidant Activity and LC MS Based Metabolite Profiling of Premna Barbata Stem Bark

Premna barbata Wall. ex Schauer is used traditionally as folkloric medicines for the treatment of differentpathological conditions. The first reported constituent from the bark of the plant was an iridoid glycoside premnosidic&nbsp;acid having antioxidant activity. Other species of this genus i.e., Premna latifolia, Premna tomentosa has shown&nbsp;to have antioxidant and cytotoxic activities. Despite the ethnomedicinal uses, no scientific evidence in support of&nbsp;antitumor activity on the stem bark of Premna barbata is reported so far. Hence, the current work aims to assess&nbsp;anticancer potentiality of different extracts of P. barbata on various cancer cell lines. Different extracts i.e., Petroleum&nbsp;ether extract (PBPE), Chloroform extract (PBCE), Ethyl acetate extract (PBEE) and Alcoholic extract (PBAE) were&nbsp;prepared and on each extract in-vitro antiproliferative activity was performed by using SRB assay. The most potent&nbsp;extract i.e., PBEE was then evaluated for antioxidant activity. Qualitative phytochemical investigation of different&nbsp;extracts indicates the presence of proteins, carbohydrates, steroids/triterpenoids, alkaloids, glycosides, flavonoids, and&nbsp;phenolic constituents. Ethyl acetate extract of Premna barbata gives potent cytotoxic activity in all cancer cell lines&nbsp;but more selectively to human colon cancer cell line (COLO-205) with GI 50 44.6 μg/ml. The phenolic and flavonoid&nbsp;content in ethyl acetate extract was 3.43±0.09 mg GE/g and 4.28±0.18mg QE/g respectively. Nineteen compounds&nbsp;were observed in positive (+) ESI mode chromatograms when LC-MS analysis was carried out. The LC-MS analysis&nbsp;by positive ionization mode, the predicted compounds such as Geniposidic acid (synonym: Premnosidic acid) and&nbsp;Rutin were detected. The cytotoxicity observed on cancerous cell lines in our study may be due to the presence&nbsp;of observed compounds. So, it can be concluded that Premna barbata stembark has remarkable cytotoxic activity&nbsp;against different tumor cell lines but the effect is more on colon cell lines as compared to others

Control of Pore Geometry in Soil Microcosms and Its Effect on the Growth and Spread of Pseudomonas and Bacillus sp.

Simplified experimental systems, often referred to as microcosms, have played a central role in the development of modern ecological thinking on issues ranging from competitive exclusion to examination of spatial resources and competition mechanisms, with important model-driven insights to the field. It is widely recognized that soil architecture is the key driver of biological and physical processes underpinning ecosystem services, and the role of soil architecture and soil physical conditions is receiving growing interest. The difficulty to capture the architectural heterogeneity in microcosms means that we typically disrupt physical architecture when collecting soils. We then use surrogate measures of soil architecture such as aggregate size distribution and bulk-density, in an attempt to recreate conditions encountered in the field. These bulk-measures are too crude and do not describe the heterogeneity at microscopic scales where microorganisms operate. In the current paper we therefore ask the following questions: (i) To what extent can we control the pore geometry at microscopic scales in microcosm studies through manipulation of common variables such as density and aggregate size?; (ii) What is the effect of pore geometry on the growth and spread dynamics of bacteria following introduction into soil? To answer these questions, we focus on Pseudomonas sp. and Bacillus sp. We study the growth of populations introduced in replicated microcosms packed at densities ranging from 1.2 to 1.6 g cm−3, as well as packed with different aggregate sizes at identical bulk-density. We use X-ray CT and show how pore geometrical properties at microbial scales such as connectivity and solid-pore interface area, are affected by the way we prepare microcosms. At a bulk-density of 1.6 g cm−3 the average number of Pseudomonas was 63% lower than at a bulk-density of 1.3 g cm−3. For Bacillus this reduction was 66%. Depending on the physical conditions, bacteria in half the samples took between 1.62 and 9.22 days to spread 1.5 cm. Bacillus did spread faster than Pseudomonas and both did spread faster at a lower bulk-density. Our results highlight the importance that soil physical properties be considered in greater detail in soil microbiological studies than is currently the case

Pharmacological evaluation of traditional claims of Himalayan <i>Citrus medica</i> L.

290-296In India, Citrus medica L. (Citron; Family: Rutaceae) is used traditionally in the treatment of many ailments like urinary calculus, tumours, constipation, carries of the teeth and as vermifuge. The present study investigated the antiurolithiatic effect of hydroalcoholic extract of root and fruit juice and anthelmintic activity of root and seed extracts of C. medica L. Ethylene glycol was used to induce urolithiasis in male Wistar rats. Treatment of urolithiatic rats with hydroalcoholic extract of C. medica L. root and fruit juice significantly lowered the elevated calcium, oxalate and phosphate levels in urine. They also increased the level of stone inhibitor (magnesium) and improved the impairment of renal functions. The mechanism of this activity may be the synergism of its diuretic activity and its ability to maintain balance between stone promoters and inhibitors. In another experiment ethanolic extract of C. medica L. root, its fractions and petroleum ether extract of its seeds were investigated for their activity against Pheretima posthuma. Two concentrations of ethanolic root extract (50 and 100 mg/ml) and its two fractions, chloroform and ethanolic (each 50 mg/ml) along with petroleum ether extract of seeds (10 % v/v emulsion) were studied in the in vitro assay, which involved determination of paralytic and death time. All the tested extracts exhibited considerable anthelmintic activities; root extract was observed more active than the seed extract

Data for spread of bacteria in soil

Dataset related to the paper 'Influence of soil structure on the spread of Pseudomonas fluorescens in soil at microscale' The objective of the study was to determine the influence of soil pore characteristics on the spread of bacteria in soil. Bacteria were introduced and locally and allowed to spread through soil. Soil was resin impregnated and the location of bacteria was observed in thin sections. X-ray CT was used to determine the physical characteristics of the pore space. The data set contains the raw data published in the accompanying paper. Treatment refers to the bulk density of the soil and 2 thin sections were counted for each sample. at each micro-site in soil pore characteristics are given in the table and the number of bacterial cells found in that section through observation and counting under the microscope. Counts are converted to cell densities. The data relate to the spread of bacteria and further analysis of the data is described in the pape

Data for spread of bacteria in soil

Dataset related to the paper 'Influence of soil structure on the spread of Pseudomonas fluorescens in soil at microscale' The objective of the study was to determine the influence of soil pore characteristics on the spread of bacteria in soil. Bacteria were introduced and locally and allowed to spread through soil. Soil was resin impregnated and the location of bacteria was observed in thin sections. X-ray CT was used to determine the physical characteristics of the pore space. The data set contains the raw data published in the accompanying paper. Treatment refers to the bulk density of the soil and 2 thin sections were counted for each sample. at each micro-site in soil pore characteristics are given in the table and the number of bacterial cells found in that section through observation and counting under the microscope. Counts are converted to cell densities. The data relate to the spread of bacteria and further analysis of the data is described in the pape

Synthesis of lignin nanoparticles from Oxytenanthera abyssinica by nanoprecipitation method followed by ultrasonication for the nanocomposite application

Lignin nanoparticles (LNPs) have a wide range of potential uses in the biomedical and environmental fields. They are used to prepare antioxidants, food packaging material, energy storage, cosmetics, thermal/light stabilizers, reinforced materials, and drug delivery. In this study, LNPs were prepared from soda lignin obtained from Oxytenanthera abyssinica using dioxane, acetone, ethanol, and acid-base solvents through the nanoprecipitation method, followed by an ultrasonic process. These methods produced four different LNPs with yields in the range of 28.5% to 88.9%. Scanning electron microscope (SEM) showed that the spherical-shaped LNPS (100–400 nm) were obtained using the acetone solvent, while irregularly shaped LNPs were formed by dioxane (150–400 nm), ethanol (40–200 nm) and acid-base (100–800 nm) solvents. The maximum zeta potential of the LNPAS samples was |-35.1 mV|, determined by the dynamic light scattering (DLS), with a particle size distribution between 91.28 and 458.7 nm. According to the energy-dispersive X-ray spectrometer (EDX) results, the sample contains the elements C, O, Si, Na, and Mo. X-ray powder diffraction (XRD) analysis showed very small crystallinity sizes ranging from 0.31 to 0.35 nm. Proton nuclear magnetic resonance (H-NMR) and Fourier transformation infrared Spectroscopy (FTIR) were used to find the functional groups in the synthesized LNPs. The Thermogravimetric analysis (TGA) peak showed that LNPS was thermally stable, and rapid mass loss occurred between 300 and 415 °C. Differential Scanning Calorimetry (DSC) data shows that the highest exothermic peaks are obtained at 345.2 °C. Synthesis of LNPs by dissolving isolated soda lignin in acetone, ethanol, dioxane, and acid-base solvents was quickly recovered, cheap, and eco-friendly. The synthesized are free of sulfur; they do not use toxic solvents such as Tetrahydrofuran (THF), Dimethyl sulfoxide (DMSO), and Dimethylformamide (DMF). Thus, they provide benefits for high-value-added Nanocomposite applications such as bio-based nonmaterial and food packaging materials. Acid-base nanoprecipitation procedure is the best approach regarding stability and size, but the acetone nanoprecipitation method is preferable regarding shape