Rapid cultivation of stable aerobic phenol-degrading granules using acetate-fed granules as microbial seed

cDNA-encoding pyranose 2-oxidase (P2O) from Trametes pubescens was sequenced and cloned into Escherichia coli strain BL21/DE3 on a multicopy plasmid under the control of trc promoter. The synthesis of P2O was studied in a batch culture in M9-based mineral medium: the enzyme was synthesized constitutively at 28 °C in amount corresponding to 8% of the cell soluble protein (0.6 U mg⁻¹). Only small portion of P2O (11%) was in the form of non-active inclusion bodies. Purified recombinant enzyme has similar physico-chemical and kinetic parameters with other P2Os. When compared to the expression of p2o of Trametes ochracea, a ratio of the mature enzyme to inclusion bodies found in the same E. coli host at 28 °C is as much as nine times higher. The finding makes the enzyme from T. pubescens preferable for the large-scale production by recombinant bacteria. The difference in amino acid sequences of the P2O from T. ochracea and T. pubescens may explain the favourable trait of the latter enzyme regarding protein folding.     

Characterization of Two Subsurface H2-Utilizing Bacteria, Desulfomicrobium hypogeium sp. nov. and Acetobacterium psammolithicum sp. nov., and Their Ecological Roles

We examined the relative roles of acetogenic and sulfate-reducing bacteria in H₂ consumption in a previously characterized subsurface sandstone ecosystem. Enrichment cultures originally inoculated with ground sandstone material obtained from a Cretaceous formation in central New Mexico were grown with hydrogen in a mineral medium supplemented with 0.02% yeast extract. Sulfate reduction and acetogenesis occurred in these cultures, and the two most abundant organisms carrying out the reactions were isolated. Based on 16S rRNA analysis data and on substrate utilization patterns, these organisms were named Desulfomicrobium hypogeium sp. nov. and Acetobacterium psammolithicum sp. nov. The steady-state H₂ concentrations measured in sandstone-sediment slurries (threshold concentration, 5 nM), in pure cultures of sulfate reducers (threshold concentration, 2 nM), and in pure cultures of acetogens (threshold concentrations 195 to 414 nM) suggest that sulfate reduction is the dominant terminal electron-accepting process in the ecosystem examined. In an experiment in which direct competition for H₂ between D. hypogeium and A. psammolithicum was examined, sulfate reduction was the dominant process.     

Usefulness of autocidal gravid ovitraps for the surveillance and control of Aedes (Stegomyia) aegypti (Diptera: Culicidae) in eastern Colombia

In the past decade, new strategies have been developed to control the Aedes aegypti (Diptera: Culicidae) mosquito vector, as well as a broad range of arboviral agents. Vector control surveillance programmes in Puerto Rico and Australia have implemented the Centers for Disease Control and Prevention autocidal gravid ovitrap (AGO), which has had an impact on vector density and, consequently, the epidemiology of arboviral infections. Colombia intends to establish the AGO as a new tool for the surveillance and control of the A. aegypti vector. AGOs were evaluated in a hyperendemic area for dengue virus during an 8-week period in Villavicencio city, eastern Colombia. The results indicated that the AGOs detect a high density of A. aegypti, with positive results for these traps of over 80% and an average catch of six individuals per trap per week. Acceptance of AGOs in the community exceeded 95%, and adherence was around 89%. This study's results demonstrate, for the first time in Colombia, that traps are a useful tool for the surveillance of A. aegypti. Future studies must consider the implementation of AGOs in the region.     

Retinal Microvascular Abnormalities and Risk of Renal Failure in Asian Populations

BackgroundRetinal microvascular signs may provide insights into the structure and function of small vessels that are associated with renal disease. We examined the relationship of retinal microvascular signs with both prevalent and incident end-stage renal disease (ESRD) in a multi-ethnic Asian population.MethodsA total of 5763 subjects (aged ≥40 years) from two prospective population-based studies (the Singapore Malay Eye Study and the Singapore Prospective Study) were included for the current analysis. Retinopathy was graded using the modified Airlie House classification system. Retinal vascular parameters were measured using computer-assisted programs to quantify the retinal vessel widths (arteriolar and venular caliber) and retinal vascular network (fractal dimension). Data on ESRD was obtained by record linkage with the ESRD cases registered by National Registry of Diseases Office, Singapore. Multi-variable adjusted regression analyses were performed to assess the associations of baseline retinal vascular parameters and prevalent and incident ESRD.ResultsAt baseline, 21(0.36%) persons had prevalent ESRD. During a median follow-up of 4.3 years, 33 (0.57%) subjects developed ESRD. In our analyses, retinopathy was associated with prevalent ESRD (multi-variable adjusted odds ratio [OR], 3.21, 95% confidence interval [CI]: 1.28–8.05) and incident ESRD (multi-variable adjusted hazard ratio [HR], 2.51, 95%CI: 1.14–5.54). This association was largely seen in person with diabetes (HR, 2.60, 95%CI: 1.01–6.66) and not present in persons without diabetes (HR, 1.65, 95%CI: 0.14–18.98). Retinal arteriolar caliber, retinal venular caliber and retinal vascular fractal dimension were not associated with ESRD.ConclusionRetinopathy signs in persons with diabetes are related to an increased risk of ESRD; however, other microvascular changes in the retina are not associated with ESRD.     

Bacterial Diversity and Function of Aerobic Granules Engineered in a Sequencing Batch Reactor for Phenol Degradation

Aerobic granules are self-immobilized aggregates of microorganisms and represent a relatively new form of cell immobilization developed for biological wastewater treatment. In this study, both culture-based and culture-independent techniques were used to investigate the bacterial diversity and function in aerobic phenol- degrading granules cultivated in a sequencing batch reactor. Denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rRNA genes demonstrated a major shift in the microbial community as the seed sludge developed into granules. Culture isolation and DGGE assays confirmed the dominance of β-Proteobacteria and high-G+C gram-positive bacteria in the phenol-degrading aerobic granules. Of the 10 phenol-degrading bacterial strains isolated from the granules, strains PG-01, PG-02, and PG-08 possessed 16S rRNA gene sequences that matched the partial sequences of dominant bands in the DGGE fingerprint belonging to the aerobic granules. The numerical dominance of strain PG-01 was confirmed by isolation, DGGE, and in situ hybridization with a strain-specific probe, and key physiological traits possessed by PG-01 that allowed it to outcompete and dominate other microorganisms within the granules were then identified. This strain could be regarded as a functionally dominant strain and may have contributed significantly to phenol degradation in the granules. On the other hand, strain PG-08 had low specific growth rate and low phenol degradation ability but showed a high propensity to autoaggregate. By analyzing the roles played by these two isolates within the aerobic granules, a functional model of the microbial community within the aerobic granules was proposed. This model has important implications for rationalizing the engineering of ecological systems.     

The mycetisms and their relevancy in medicine.

Poisonous mushrooms play an important role in public health, since the poisonings caused by their toxins have very high morbidity-mortality rates. No real data are available on this problem because diagnosis is often difficult. This work points out the important role of poisonous mushrooms. An analysis is included of the clinical features of the most important mycetisms, the mushrooms that produce them and the toxins that cause this pathology. A guide to aid clinical doctors in the diagnosis and treatment of mycetisms and recomendations to prevent these poisonings are provided.     

Do mitochondria make nitric oxide? no?

Several papers have claimed that mitochondria contain nitric oxide synthase (NOS) and make nitric oxide (NO*) in amounts sufficient to affect mitochondrial respiration. However, we found that the addition of L-arginine or the NOS inhibitor L-NMMA to intact rat liver mitochondria did not have any effect on the respiratory rate in both State 3 and State 4. We did not detect mitochondrial NO* production by the oxymyoglobin oxidation assay, or electrochemically using an NO* electrode. An apparent NO* production detected by the Griess assay was identified as an artifact. NO* generated by eNOS added to the mitochondria could easily be detected, although succinate-supplemented mitochondria appeared to consume NO*. Our data show that NO* production by normal rat liver mitochondria cannot be detected in our laboratory, even though the levels of production claimed in the literature should easily have been measured by the techniques used. The implications for the putative mitochondrial NOS are discussed.     

Intestinal candidiasis. A clinical report and comments about this opportunistic pathology

An eight-years-old girl, who presented with recurrent upper respiratory tract infections, was treated with broad-spectrum antibiotics. Afterward she presented with intestinal candidiasis. The isolated species was identified as Candida albicans by differential tests. Treatment given was with 500,000 IU of oral nystatin every 8 hours for 10 days and intestinal normal microbiota restoratives. Evolution has been satisfactory, although concomitantly type A hepatitis developed. Rest and a soft diet were recommended. The child is now perfectly healthy with normal liver function tests. CONCLUSION: Prolonged treatments with broad-spectrum antibiotics destroyed the indigenous intestinal microbiota, which provoked intestinal C. Albicans proliferation and adversely affected the immunological system of the patient, thus facilitating the establishment of a viral infection.