Plasmid-encoded copper resistance and precipitation by Mycobacterium scrofulaceum.

A copper-tolerant Mycobacterium scrofulaceum strain was able to remove copper from culture medium by sulfate-dependent precipitation as copper sulfide. Such precipitation of copper sulfide was not observed in a derivative that lacks a 173-kilobase plasmid. In addition, the plasmid-carrying strain has a sulfate-independent copper resistance mechanism.     

Occurrence of Nontuberculous Mycobacterial Pulmonary Infection in an Endemic Area of Tuberculosis

The majority of investigations of the epidemiology of nontuberculous mycobacteria (NTM) have focused on highly developed nations with a low prevalence of tuberculosis. In contrast, the Para state of north Brazil represents an area of high tuberculosis prevalence and increasing NTM incidence. Toward the goal of understanding the dynamics of infection by all Mycobacterium species, we report patient characteristics and the identification of NTM strains isolated from sputum samples from patients that were residents of Para, a state in the Amazon region, Northern of Brazil, over the period January 2010 through December 2011 (2 years). The 29 NTM patients comprised 13.5% of positive mycobacterial cultures over the 2-year period. A major risk factor for NTM pulmonary disease was previous tuberculosis (76%). Further, the average age of NTM patients (52 years) was significantly higher than that of tuberculosis patients (39 years) and more were female (72.4% vs. 37.4%). Unlike other Brazilian states, NTM pulmonary patients in Para were infected with a different spectrum of mycobacteria; primarily the rapidly growing Mycobacterium massiliense and Mycobacterium simiae complex.     

Role of hydrophobicity in bacterial adherence to carbon nanostructures and biofilm formation

The role of cell and surface hydrophobicity in the adherence of the waterborne bacterium Mycobacterium smegmatis to nanostructures and biofilm formation was investigated. Carbon nanostructures (CNs) were synthesized using a flame reactor and deposited on stainless steel grids and foils, and on silicon wafers that had different initial surface hydrophobicities. Surface hydrophobicity was measured as the contact angle of water droplets. The surfaces were incubated in suspensions of isogenic hydrophobic and hydrophilic strains of M. smegmatis and temporal measurements of the numbers of adherent cells were made. The hydrophobic, rough mutant of M. smegmatis adhered more readily and formed denser biofilms on all surfaces compared to its hydrophilic, smooth parent. Biofilm formation led to alterations in the hydrophobicity of the substratum surfaces, demonstrating that bacterial cells attached to CNs are capable of modifying the surface characteristics.     

A role for oxalic acid generation in ozone‐induced signallization in Arabidopis cells

Ozone (O₃) is an air pollutant with an impact increasingly important in our industrialized world. It affects human health and productivity in various crops. We provide the evidences that treatment of Arabidopsis thaliana with O₃ results in ascorbate‐derived oxalic acid production. Using cultured cells of A. thaliana as a model, here we further showed that oxalic acid induces activation of anion channels that trigger depolarization of the cell, increase in cytosolic Ca²⁺ concentration, generation of reactive oxygen species and cell death. We confirmed that O₃ reacts with ascorbate in the culture, thus resulting in production of oxalic acid and this could be part of the O₃‐induced signalling pathways that trigger programmed cell death.     

Cryptic plasmids of Mycobacterium avium: Tn552 to the rescue

Plasmids have been described in almost all bacterial species analysed and have proven to be essential genetic tools. In many bacteria these extrachromosomal DNAs are cryptic with no known markers or function, which makes their characterization and genetic exploitation extremely difficult. Here we describe a system that will allow the rescue of any circular DNA (plasmid or phage) using an in vitro transposition system to deliver both a selectable marker (kanamycin) and an Escherichia coli plasmid origin of replication. In this study, we demonstrate the rescue of four cryptic plasmids from the opportunistic pathogen Mycobacterium avium. To evaluate the host range of the rescued plasmids, we have examined their ability to be propagated in Mycobacterium smegmatis and Mycobacterium bovis BCG, and their compatibility with other mycobacterial plasmids. In addition, we use a library of transposon insertions to sequence one plasmid, pVT2, and to begin a genetic analysis of plasmid genes. Using this approach, we identified a putative conjugative relaxase, suggesting this myco-bacterial plasmid is transferable, and three genes required for plasmid establishment and replication.     

Identification and characteristics of a novel Burkholderia strain with broad-spectrum antimicrobial activity

A Burkholderia strain isolated from soil is capable of inhibiting the growth of bacteria, plant-pathogenic fungi, pathogenic yeasts, and protozoa. Inhibition does not involve cell contact or the presence of living cells, suggesting that at least a substantial portion of the antimicrobial activity is due to the excretion of extracellular compounds.     

Preliminary estimates of the potential for carbon mitigation in European soils through no-till farming

In this paper we estimate the European potential for carbon mitigation of no-till farming using results from European tillage experiments. Our calculations suggest some potential in terms of (a) reduced agricultural fossil fuel emissions, and (b) increased soil carbon sequestration. We estimate that 100% conversion to no-till farming would be likely to sequester about 23 Tg C y^–1 in the European Union or about 43 Tg C y^–1 in the wider Europe (excluding the former Soviet Union). In addition, up to 3.2 Tg C y^–1 could be saved in agricultural fossil fuel emissions. Compared to estimates of the potential for carbon sequestration of other carbon mitigation options, no-till agriculture shows nearly twice the potential of scenarios whereby soils are amended with organic materials. Our calculations suggest that 100% conversion to no-till agriculture in Europe could mitigate all fossil fuel-carbon emissions from agriculture in Europe. However, this is equivalent to only about 4.1% of total anthropogenic CO₂-carbon produced annually in Europe (excluding the former Soviet Union) which in turn is equivalent to about 0.8% of global annual anthropogenic CO₂-carbon emissions.     

Effects of fine‐scale genetic structure on male mating success in gynodioecious Beta vulgaris ssp. maritima

Plant mating systems are known to influence population genetic structure because pollen and seed dispersal are often spatially restricted. However, the reciprocal outcomes of population structure on the dynamics of polymorphic mating systems have received little attention. In gynodioecious sea beet (Beta vulgaris ssp. maritima), three sexual types co‐occur: females carrying a cytoplasmic male sterility (CMS) gene, hermaphrodites carrying a non‐CMS cytoplasm and restored hermaphrodites that carry CMS genes and nuclear restorer alleles. This study investigated the effects of fine‐scale genetic structure on male reproductive success of the two hermaphroditic forms. Our study population was strongly structured and characterized by contrasting local sex‐ratios. Pollen flow was constrained over short distances and depended on local plant density. Interestingly, restored hermaphrodites sired significantly more seedlings than non‐CMS hermaphrodites, despite the previous observation that the former produce pollen of lower quality than the latter. This result was explained by the higher frequency of females in the local vicinity of restored (CMS) hermaphrodites as compared to non‐CMS hermaphrodites. Population structure thus strongly influences individual fitness and may locally counteract the expected effects of selection, suggesting that understanding fine scale population processes is central to predicting the evolution of gender polymorphism in angiosperms.