Preparation of N2, N2,7-trimethylguanosine affinity columns

2,2,7-trimethylguanosine (TMG) binding proteins from human cells were purified through TMG-affinity columns. TMG synthesis was improved and the TMG obtained was shown to be similar to the TMG in the 5' cap of the UsnRNAs. The eluates obtained with TMG-affinity chromatographies were very different from those isolated with m7G-affinity columns, thus suggesting that specific TMG-binding proteins were obtained. The fraction may be enriched with factors associated with import and/or hypermethylation of UsnRNPs.     

Functional and ultrastructural changes in Pseudomonas aeruginosa and Staphylococcus aureus cells induced by Cinnamomum verum essential oil

Aims: To study cellular damage induced by Cinnamomum verum essential oil in Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 29213. Methods and Results: The effect of cinnamon bark essential oil on these two strains was evaluated by plate counts, potassium leakage, flow cytometry and transmission electron microscopy (TEM). Exposure to this oil induced alterations in the bacterial membrane of Ps. aeruginosa, which led to the collapse of membrane potential, as demonstrated by bis‐oxonol staining, and loss of membrane‐selective permeability, as indicated by efflux of K⁺ and propidium iodide accumulation. Thus, respiratory activity was inhibited, leading to cell death. In Staph. aureus, cells treated with the oil entered a viable but noncultivable (VNC) state. The oil initially caused a considerable decrease in the metabolic activity and in the replication capacity of these bacterial cells. The loss of membrane integrity appeared later, as indicated by bis‐oxonol and Propidium iodide (PI) staining. Data provided by TEM showed various structural effects in response to cinnamon essential oil. In Ps. aeruginosa cells, coagulated cytoplasmic material was observed, and intracellular material was seen in the surrounding environment, while oil‐treated Staph. aureus showed fibres extending from the cell surface. Conclusions: Cinnamon essential oil damages the cellular membrane of Ps. aeruginosa, which leads to cell death. There is evidence of VNC Staph. aureus after exposure to the oil. Significance and Impact of the Study: Cinnamon essential oil shows effective antimicrobial activity and health benefits and is therefore considered a potential food additive. To use this oil as a natural food preservative, especially in combination with other preservation methods, a thorough understanding of the mechanism through which this oil exerts its antibacterial action is required.     

R-bodies inPseudomonas aeruginosa strain 44T1

For the first time R-bodies are described in a new strain 44T1 ofPseudomonas aeruginosa. Its size was measured as being 0.22 to 0.37 m of width per 0.27 to 0.41 m of length and 5 to 9 spiral turns about 16 nm. These structures are similar to previously observed in bacteria and are related with physiological state of bacteria in minimal conditions of growth.     

Selection and symbiotic properties ofRhizobium leguminosarum biovarphaseoli strains harboring pRtr5a

TheRhizobium leguminosarum biovartrifolii symbiotic plasmid pRtr5a has been transferred toR. leguminosarum biovarphaseoli RCR 3644-S1. The transconjugant selection had been done byTrifolium pratense plants. All transconjugants lacked the resident pSym, but had complete pRtr5a, and were Fix⁺ onT. repens andT. alexandrinum, Fix^– onT. subterraneum, and formed a few small white and Fix^– nodules onPhaseolus vulgaris. It is shown that this nodulation onP. vulgaris is due to pRtr5a. The presence of pRtr5a and/or the passage throughTrifolium pratense nodules provoke(s) the recipient strain symbiotic plasmid loss.     

Bacterial Community Dynamics and Polycyclic Aromatic Hydrocarbon Degradation during Bioremediation of Heavily Creosote-Contaminated Soil

Bacterial community dynamics and biodegradation processes were examined in a highly creosote-contaminated soil undergoing a range of laboratory-based bioremediation treatments. The dynamics of the eubacterial community, the number of heterotrophs and polycyclic aromatic hydrocarbon (PAH) degraders, and the total petroleum hydrocarbon (TPH) and PAH concentrations were monitored during the bioremediation process. TPH and PAHs were significantly degraded in all treatments (72 to 79% and 83 to 87%, respectively), and the biodegradation values were higher when nutrients were not added, especially for benzo(a)anthracene and chrysene. The moisture content and aeration were determined to be the key factors associated with PAH bioremediation. Neither biosurfactant addition, bioaugmentation, nor ferric octate addition led to differences in PAH or TPH biodegradation compared to biodegradation with nutrient treatment. All treatments resulted in a high first-order degradation rate during the first 45 days, which was markedly reduced after 90 days. A sharp increase in the size of the heterotrophic and PAH-degrading microbial populations was observed, which coincided with the highest rates of TPH and PAH biodegradation. At the end of the incubation period, PAH degraders were more prevalent in samples to which nutrients had not been added. Denaturing gradient gel electrophoresis analysis and principal-component analysis confirmed that there was a remarkable shift in the composition of the bacterial community due to both the biodegradation process and the addition of nutrients. At early stages of biodegradation, the α-Proteobacteria group (genera Sphingomonas and Azospirillum) was the dominant group in all treatments. At later stages, the γ-Proteobacteria group (genus Xanthomonas), the α-Proteobacteria group (genus Sphingomonas), and the Cytophaga-Flexibacter-Bacteroides group (Bacteroidetes) were the dominant groups in the nonnutrient treatment, while the γ-Proteobacteria group (genus Xathomonas), the β-Proteobacteria group (genera Alcaligenes and Achromobacter), and the α-Proteobacteria group (genus Sphingomonas) were the dominant groups in the nutrient treatment. This study shows that specific bacterial phylotypes are associated both with different phases of PAH degradation and with nutrient addition in a preadapted PAH-contaminated soil. Our findings also suggest that there are complex interactions between bacterial species and medium conditions that influence the biodegradation capacity of the microbial communities involved in bioremediation processes.     

Screening and selection of surfactant-producing bacteria from waste lubricating oil

Forty-four strains with the ability to grow on waste lubricating oil as sole carbon source were isolated from soil-contaminated samples and identified. Of these, four Rhodococcus and one Bacillus strain were selected for their capacity to lower the surface tension of culture medium from 55 mN m^-1 to less than or equal to 40 mN m^-1 and the interfacial tension between the culture medium and kerosene from 21 mN m^-1 to less than 5 mN m^-1, respectively. The surface-active compounds, identified by means of TLC and specific reagents, from cultures of Rhodococcus strains and Bacillus were glycolipids and lipopeptide, respectively. The percentage loss of waste lubricating oil after 120 h of incubation ranged from 7.87% to 45.8% depending on the strain selected compared with uninoculated control. Decreases in paraffinic compounds and accumulation of new products, mainly with amide groups, were observed by direct and differential infrared spectrometry when selected strains grew on waste lubricating oil.     

A catalogue of molecular, physiological and symbiotic properties of soybean-nodulating rhizobial strains from different soybean cropping areas of China

We have analysed 198 fast-growing soybean-nodulating rhizobial strains from four different regions of China for the following characteristics: generation time; number of plasmids; lipopolysaccharide (LPS), nodulation factors (LCOs) and PCR profiles; acidification of growth medium; capacity to grow at acid, neutral, and alkaline pH; growth on LC medium; growth at 28 and 37 degrees C; melanin production capacity; Congo red absorption and symbiotic characteristics. These unbiased analyses of a total subset of strains isolated from specific soybean-cropping areas (an approach which could be called "strainomics") can be used to answer various biological questions. We illustrate this by a comparison of the molecular characteristics of five strains with interesting symbiotic properties. From this comparison we conclude, for instance, that differences in the efficiency of nitrogen fixation or competitiveness for nodulation of these strains are not apparently related to differences in Nod factor structure.     

Preliminary studies on the production ani composition of the extracellular polysaccharide synthesized byPseudomonas sp. EPS-5028

Summary Exopolysaccharide production byPseudomonas sp. strain EPS-5028 increased under conditions of high C/N ratios at the pH range 6.7–8 and 25°C. The polymer was formed from a variety of carbon substrates and contains D-glucose, D-galactose and uronic acid in the approximate molar ratio of 325. The polysaccharide produced is of high viscosity (1,600 cP; 1% polymer in D. I. water).