Analysis of Blueberry Plant Rhizosphere Bacterial Diversity and Selection of Plant Growth Promoting Rhizobacteria.

Microbial metabolites in rhizosphere soil are important to plant growth. In this study, microbial diversity in blueberry plant rhizosphere soil was characterized using high-throughput amplicon sequencing technology. There were 11 bacterial phyla and three fungal phyla dominating in the soil. In addition, inorganic-phosphate-solubilizing bacteria (iPSB) in the rhizosphere soil were isolated and evaluated by molybdenum-antimony anti-coloration method. Their silicate solubilizing, auxin production, and nitrogen fixation capabilities were also determined. Eighteen iPSB in the rhizosphere soil strains were isolated and identified as Buttiauxella, Paraburkholderia and Pseudomonas. The higher phosphorus-solubilizing capacity and auxin production in blueberry rhizosphere belonged to genus Buttiauxella sp. The strains belong to genus Paraburkholderia had the same function of dissolving both phosphorus and producing auxin, as well as silicate and nitrogen fixation. The blueberry seeds incubated with the strains had higher germination rates. The results of this study could be helpful in developing the plant growth-promoting rhizobacteria (PGPR) method for enhancing soil nutrients to blueberry plant.

Influence of silicon treatment on antimony uptake and translocation in rice genotypes with different radial oxygen loss.

Antimony (Sb) pollution in soil may have a negative impact on the health of people consuming rice. This study investigated the effect of silicon (Si) application on rice biomass, iron plaque formation, and Sb uptake and speciation in rice plants with different radial oxygen loss (ROL) using pot experiments. The results demonstrated that Si addition increased the biomass of straw and grain, but had no obvious impact on the root biomass. Indica genotypes with higher ROL underwent greater iron plaque formation and exhibited more Sb sequestration in iron plaque. Silicon treatments increased iron levels in iron plaque from the different genotypes but decreased the total Sb concentration in root, straw, husk, and grain. In addition, Si treatment reduced the inorganic Sb concentrations but slightly increased the trimethylantimony (TMSb) concentrations in rice straw. Moreover, rice straw from hybrid genotypes accumulated higher concentrations of TMSb and inorganic Sb than that from indica genotypes. The conclusions from this study indicate that Sb contamination in rice can be efficiently reduced by applying Si treatment and selecting genotypes with high ROL.

The effect of selenium on the subcellular distribution of antimony to regulate the toxicity of antimony in paddy rice.

Selenium (Se) can alleviate the toxicity of antimony (Sb) in plants; however, the associated mechanisms have not been fully clarified. In this study, we hypothesize that Se can affect the subcellular distribution of Sb to regulate Sb toxicity. To test our hypothesis, two nested hydroponic experiments were performed by using paddy rice (Fengmeizhan). The results showed that Sb exerted toxic effects on the growth of paddy rice, and Se caused beneficial effects that were limited to the shoot growth. In general, Se and Sb mutually showed antagonistic effects on their uptake and concentrations in different subcellular fractions. However, in some cases, the stimulation effects of Sb on the Se concentration in chlorophyll (Chl) and cytosol (Cy) fractions or of Se on the Sb concentration in the cell wall fraction (Cw) were also observed in the shoots, which might suggest that Sb detoxification by Se is also related to the migration of both Se and Sb in cells. Selenium and Sb were primarily concentrated in the Cw and Cy, suggesting the important roles of these two fractions in detoxifying Se and Sb. When paddy rice was subjected to increasing Sb concentrations and a fixed Se concentration, most of the Se in the shoots was sequestered in the Cy (59.81-79.51% of total Se) and more Se was transferred into the inner cell from Cw; however, in the roots, Se was primarily concentrated in the Cw (53.28-72.10%). When paddy rice was exposed to increasing Se concentrations with a fixed Sb concentration, the Cw in both the shoots and roots might play an important role in binding Se, especially in the roots where up to 78.92% of the total Se was sequestered in the Cw.

Bioaccumulation and biovolatilization of various elements using filamentous fungus Scopulariopsis brevicaulis.

UNLABELLED: Biovolatilization and bioaccumulation capabilities of different elements by microscopic filamentous fungus Scopulariopsis brevicaulis were observed. Accumulation of As(III), As(V), Se(IV), Se(VI), Sb(III), Sb(V), Te(IV), Te(VI), Hg(II), Tl(I) and Bi(III) by S. brevicaulis was quantified by analysing the amount of elements in biomass of the fungus using ICP AAS. The highest amounts of bioaccumulated metal(loid)s were obtained as follows: Bi(III) > Te(IV) > Hg(II) > Se(IV) > Te(VI) > Sb(III) at different initial contents, with Bi(III) accumulation approximately 87%. The highest percentages of volatilization were found using Hg(II) (50%) and Se(IV) (46·5%); it was also demonstrated with all studied elements. This proved the biovolatilization ability of microscopic fungi under aerobic conditions. The highest removed amount was observed using Hg(II) (95·30%), and more than 80% of Se(IV), Te(IV), Bi(III) and Hg(II) was removed by bioaccumulation and biovolatilization, which implies the possibilities of use of these processes for bioremediations. There were reported significant differences between bioaccumulation and biovolatilization of almost all applied metal(loid)s if valence is mentioned. SIGNIFICANCE AND IMPACT OF THE STUDY: Microbial accumulation and volatilization are natural processes involved in biogeochemical cycles of elements. Despite their impact on mobility, bioavailability and toxicity of various metal(loid)s, only few papers deal with these processes under aerobic conditions with microscopic fungi. Thus, the proving of ability of microscopic fungus Scopulariopsis brevicaulis to accumulate and transform metals and metalloids by methylation or alkylation and quantification of these processes were demonstrated. The results can provide basic information on natural elements cycling and background for more specific studies focusing, for example, on application of these processes in mitigation of metal(loid) contamination.

Effects of nutrient and lime additions in mine site rehabilitation strategies on the accumulation of antimony and arsenic by native Australian plants.

The effects of nutrient and lime additions on antimony (Sb) and arsenic (As) accumulation by native Australian and naturalised plants growing in two contaminated mine site soils (2,735 mg kg(-1) and 4,517 mg kg(-1) Sb; 826 mg kg(-1) and 1606 As mgkg(-1)) was investigated using a glasshouse pot experiment. The results indicated an increase in soil solution concentrations with nutrient addition in both soils and also with nutrient+lime addition for Sb in one soil. Metalloid concentrations in plant roots were significantly greater than concentrations in above ground plant parts. The metalloid transfer to above ground plant parts from the roots and from the soil was, however, low (ratio of leaf concentration/soil concentration≪1) for all species studied. Eucalyptus michaeliana was the most successful at colonisation with lowest metalloid transfer to above ground plant parts. Addition of nutrients and nutrients+lime to soils, in general, increased plant metalloid accumulation. Relative As accumulation was greater than that of Sb. All the plant species studied were suitable for consideration in the mine soil phytostabilisation strategies but lime additions should be limited and longer term trials also recommended.

The effect of age on Ag, Co, Cr, Fe, Hg, Rb, Sb, Sc, Se, and Zn contents in intact human prostate investigated by neutron activation analysis.

The effect of age on trace element contents in intact prostate of 64 apparently healthy 13-60 years old men was investigated by neutron activation analysis. Mean values (M±SΕΜ) for content (mg/kg, dry weight basis) of trace elements were: Ag-0.057±0.007, Co-0.036±0.003, Cr-0.48±0.06, Fe-96.9±6.2, Hg-0.045±0.006, Rb-12.5±0.6, Sb-0.050±0.005, Sc-0.020±0.003, Se-0.63±0.03, and Zn-548±55, respectively. A tendency of age-related increase in Co, Fe, Hg, Sc, and Zn content was observed.

Production of volatile derivatives of metal(loid)s by microflora involved in anaerobic digestion of sewage sludge.

Gases released from anaerobic wastewater treatment facilities contain considerable amounts of volatile methyl and hydride derivatives of metals and metalloids, such as arsine (AsH(3)), monomethylarsine, dimethylarsine, trimethylarsine, trimethylbismuth (TMBi), elemental mercury (Hg(0)), trimethylstibine, dimethyltellurium, and tetramethyltin. Most of these compounds could be shown to be produced by pure cultures of microorganisms which are representatives of the anaerobic sewage sludge microflora, i.e., methanogenic archaea (Methanobacterium formicicum, Methanosarcina barkeri, Methanobacterium thermoautotrophicum), sulfate-reducing bacteria (Desulfovibrio vulgaris, D. gigas), and a peptolytic bacterium (Clostridium collagenovorans). Additionally, dimethylselenium and dimethyldiselenium could be detected in the headspace of most of the pure cultures. This is the first report of the production of TMBi, stibine, monomethylstibine, and dimethylstibine by a pure culture of M. formicicum.

Antimony in drinking water, red blood cells, and serum: development of analytical methodology using transversely heated graphite furnace atomization-atomic absorption spectrometry.

An atomic absorption spectrometric (AAS) method has been developed for determining microg/L levels of Sb in samples of water and blood. The AAS method is based on the concept of stabilized temperature platform furnace atomization (STPF) realized through the use of a transversely heated graphite atomizer (THGA) furnace, longitudinal Zeeman-effect background correction, and matrix modification with palladium nitrate-magnesium nitrate-nitric acid. The method of standard additions is not mandatory. The detection limit (3 standard deviations of the blank) is 2.6 microg Sb/L for the water, red blood cells (RBCs), and serum samples. Data are presented on the degree of accuracy and precision. The THGA-AAS method is simple, fast, and contamination-free because the entire operation from sampling to AAS measurement is carried out in the same tube. The method has been applied to the determination of Sb in some leachate tap water samples derived from a static copper plumbing system containing Sn/Sb solders, and in small samples (0.5 ml) of RBCs and serum derived from rats given Sb-supplemented drinking water.

Use of INAA to study Se, Sb, Zn and Co levels of yeast cells.

Yeast cells, Saccharomyces cerevisiae, were exposed to Sb(V)(10-5M) and SeO2(10-4M) or seleno-cystine (CySe)2(5 x 10-5M). Se, Sb, Zn and Co levels of the yeast were measured by instrumental neutron activation analysis. The results obtained show that in the absence of Se, Sb is taken up by the cells and the highest concentration of Sb in the yeast was observed during the initial 2.5 h of incubation. Both Se-compounds resulted, in general, in a minute decrease of uptake yield of Sb by the cells. This effect can be particularly observed in the presence of SeO2. The presence of Sb in the yeast medium slightly increased the Se level only after long incubation times. Se uptake by the yeast was higher (regardless of Sb dosage) when the yeast was incubated in the medium containing (CySe)2 (in comparison with SeO2). The presence of Se-compounds and/or Sb caused decrease in the levels of Zn found in the cells. While SeO2 presence resulted in minor changes of the Co level of the yeast, the combined presence of Sb and Se-compounds produced the significant enhancement of Co abundance. The similar effect was noted in the yeast incubated in a medium containing only (CySe)2 or Sb.