Genomic analyses of metal resistance genes in three plant growth promoting bacteria of legume plants in Northwest mine tailings,China

To better understand the diversity of metal resistance genetic determinant from microbes that survived at metal tailings in northwest of China, a highly elevated level of heavy metal containing region, genomic analyses was conducted using genome sequence of three native metal-resistant plant growth promoting bacteria(PGPB). It shows that: Mesorhizobium amorphae CCNWGS0123 contains metal transporters from P-type ATPase, CDF(Cation Diffusion Facilitator), Hup E/Ure J and CHR(chromate ion transporter) family involved in copper, zinc, nickel as well as chromate resistance and homeostasis. Meanwhile, the putative Cop A/Cue O system is expected to mediate copper resistance in Sinorhizobium meliloti CCNWSX0020 while Znt A transporter, assisted with putative Czc D, determines zinc tolerance in Agrobacterium tumefaciens CCNWGS0286. The greenhouse experiment provides the consistent evidence of the plant growth promoting effects of these microbes on their hosts by nitrogen fixation and/or indoleacetic acid(IAA) secretion,indicating a potential in-site phytoremediation usage in the mining tailing regions of China.     

Assessment of lead pollution in topsoils of a southern Italy area: Analysis of urban and peri-urban environment

Exposure to lead (Pb) may affect adversely human health. Mapping soil Pb contents is essential to obtain a quantitative estimate of potential risk of Pb contamination. The main aim of this paper was to determine the soil Pb concentrations in the urban and peri-urban area of Cosenza–Rende to map their spatial distribution and assess the probability that soil Pb concentration exceeds a critical threshold that might cause concern for human health. Samples were collected at 149 locations from residual and non-residual topsoil in gardens, parks, flower-beds, and agricultural fields. Fine earth fraction of soil samples was analyzed by X-ray Fluorescence spectrometry. Stochastic images generated by the sequential Gaussian simulation were jointly combined to calculate the probability of exceeding the critical threshold that could be used to delineate the potentially risky areas. Results showed areas in which Pb concentration values were higher to the Italian regulatory values. These polluted areas were quite large and likely, they could create a significant health risk for human beings and vegetation in the near future. The results demonstrated that the proposed approach can be used to study soil contamination to produce geochemical maps, and identify hot-spot areas for soil Pb concentration.     

Hydrologic impacts of brush management with tebuthiuron and prescribed burning on post oak savannah watersheds,Texas

Selected hydrologic variables were evaluated following conversion of heavily wooded sites to open grassland with a herbicide—prescribed burning treatment sequence in east-central Texas. Terminal infiltration rates and sediment production 3 years after aerial application of tebuthiuron pellets at 2.2 kg ha^?1 (active ingredient) for brush management differed little from values for untreated (wooded) areas. Prescribed burning in the winter (December–February) temporarily decreased infiltration rates and increased sediment production. Infiltration rates has equilibrated among brush management treatments with re-instatement of the herbaceous cover 5.5 months after burning. Sediment production was generally greater from burned than unburned plots after 5.5 months, but the absolute amount of sediment produced on the near-level (1–3% slope) fine sandy loam sites was not great, regardless of treatment. Moreover, sediment production from burned sites was not significantly different from that of untreated sites 1 year after burning. The brush management treatments had no effect on nitrate concentrations in run-off. However, in one of two experiments, total unfiltered nitrogen and phosphorus contents in run-off were greater during the growing season following burning than from unburned sites.