Highlights • Rapidly growing mycobacteria (RGM) are opportunistic pathogens associated with outbreaks. • Conventional identification of RGM species is laborious and uncertain. • Molecular techniques ...provide relevant information on diagnosis and clonality. • Multilocus enzyme electrophoresis (MLEE) was found to be a powerful tool for the identification and typing of epidemic RGM species.
Almeida, P.M.M.; Cruz, C.B.M.; Amaral, F.G.; Furtado, L.F.A.; Duarte, G.S.; Silva, G.F.; Barros, R.S.; Marques, J.V.F.P.A.; Rosário, E.S.; Santos, V.F.; Alves, A.; Chaves, F.O., and Soares, M.L.G., ...2020. Mangrove typology: A proposal for mapping based on high spatial resolution orbital remote sensing. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 1-5. Coconut Creek (Florida), ISSN 0749-0208. Solutions to improve environmental management strategies increasingly require the adoption of new techniques, such as Geotechnologies. All this effort must be carried out in a multidisciplinary way, using different concepts, techniques and scientific visions about the same phenomenon. In response to the cartographic demands, one of the primordial steps for a good mapping starts before the processing of the images to be used. This step is based on the definition of a legend related to the scale and purpose of the mapping. This work aims to contribute in the definition of a typology adapted to the use of high spatial resolution remote sensing data for the mapping of mangrove phytophysiognomies in the Brazilian Equatorial Coast. The final mapping covered more than 27,000 ha of forests divided into the following classes: (i) Forest dominated by Avicennia schaueriana; (ii) Forest dominated by Rhizophora spp.; (iii) Mixed Forests; all indicating differences in structural development (high, medium or low). Through this reflexive process, this work contributes to the mapping with effectively transdisciplinary strategies.
The application of bio-based biodegradable mulch films in agriculture has raised environmental concerns regarding their potential impacts on adjacent freshwater ecosystems. This study investigated ...the biodegradation of microplastics derived from a bio-based biodegradable mulch (bio-MPs) and its acute and chronic ecotoxicity considering relevant scenarios (up to 200 and 250 mg/kg of sediment, using pristine and/or UV-aged particles), using the fungus Penicillium brevicompactum and the dipteran Chironomus riparius as model organisms, respectively, due to their ecological relevance in freshwater environments.
Fourier-transform infrared spectroscopy analysis suggested changes in the fungus's carbohydrate reserves and bio-MP degradation through the appearance of low molecular weight esters throughout a 28 day biodegradation test. In a short-term exposure (48 h), C. riparius larvae exposed to pristine or UV-aged bio-MPs had up to 2 particles in their gut. Exposure to pristine bio-MPs decreased larval aerobic metabolism (<20 %) and increased neurotransmission (>15 %), whereas exposure to UV-aged bio-MPs activated larval aerobic metabolism (>20 %) and increased antioxidant defences (catalase activity by >30 % and glutathione-s-transferase by >20 %) and neurotransmission (>30 %). Longer-term (28-d) exposure to UV-aged bio-MPs did not affect larval survival and growth nor the dipteran's emergence but increased male numbers (>30 %) at higher concentrations.
This study suggests that the selected agricultural bio-based mulch film is prone to biodegradation by a naturally occurring fungus. However, there is a potential for endocrine disruption in the case of prolonged exposures to UV-aged microplastics. This study emphasises the importance of further research to elucidate the potential ecological effects of these plastic products, to ensure effective management practices, and to establish new regulations governing their use.
Display omitted
•Bio-based biodegradable mulch (bio-MPs) revealed biodegradability by P. brevicompactum.•Pristine bio-MPs decreased C. riparius aerobic metabolism and increased neurotransmission.•UV-aged bio-MPs increased C. riparius metabolism, antioxidant defences and neurotransmission.•UV-aged bio-MPs increased C. riparius male numbers at the highest concentrations.
An extension of the Oberbeck–Boussinesq approximation (OB) with expressive thermal effects is investigated to model specific mass with a temperature-dependent approach. An expansion of OB is proposed ...using a mathematical formulation with null velocity divergence in the continuity equation and variable specific mass in the momentum and energy equations (NOB). The NOB method has been previously tested in the literature, and the present paper aims to carry out a quantitative analysis between NOB and OB. The specific mass is calculated based on the temperature field and a divergence-free velocity is imposed on the NOB due to the small effects of variations of the specific mass in the continuity equation, as previously demonstrated by the OB. The purpose of the NOB is to overcome the OB’s restriction to single-phase flows, as well as to model the effects of specific mass variations more accurately, especially in problems with prominent thermal transfer effects, as that occur in the turbulent regime. Since the effects of a variable specific mass in the momentum and energy equations were taken into account by the NOB, it was expected that the thermal transfer results of the NOB would be improved compared with those of the OB. Then, three-dimensional natural convection simulations for a large range of Rayleigh numbers were performed using OB and NOB in a cubic cavity. Turbulence modeling was performed using Large Eddy Simulation (LES). Numerical results from both approaches were validated and all the results presented good quality. Thermal transfer was evaluated by the calculation of the Nusselt number at the heated wall and compared to experimental data from the literature. The OB and NOB provided adequate thermal transfer rate results; however, the differences between the literature and OB were higher than for NOB. Therefore, NOB is presented as a useful mathematical formulation for modeling incompressible flows with a temperature-dependent specific mass approach in single-phase or multiphase problems instead of solving the full compressible mathematical formulation. In addition, the differences between the literature and OB results increased as the Rayleigh number was raised, especially in the turbulent regime. The results of the NOB were closer to the literature than were those of the OB for the entire range of Rayleigh numbers tested. Therefore, the numerical results confirmed the higher accuracy of NOB compared to OB despite the NOB’s still being an approximate model. Lastly, flow visualization allowed the identification of coherent turbulent structures near the cavity walls in the simulation with Rayleigh number
10
10
. The presence of hairpin and Tollmien–Schlichting instabilities revealed the importance of modeling the three-dimensional effects of natural convection in the turbulent regime.
An aqueous extract and fraction from the marine sponge Petromica citrina have antibacterial activity. We performed a chemical and biological characterization of the antibiotic substance from P. ...citrina and investigated its mode of action on Staphylococcus aureus cells.
The inhibitory activity of the aqueous extract of P. citrina was determined against 14 bacteria belonging to type strains and clinical antibiotic-resistant strains. The aqueous extract was fractionated under bioassay guidance and the bioactive substance was identified by its (1)H-NMR, (13)C-NMR and mass spectra. The MIC and the MBC of this substance were determined. This substance was also subjected to cytotoxic bioassays. The mode of action on S. aureus cells was investigated by light and transmission electron microscopy analysis.
P. citrina showed a large spectrum of activity against type strains and resistant-bacteria such as S. aureus, Staphylococcus epidermidis, Enterococcus faecalis, Mycobacterium fortuitum and Neisseria gonorrhoeae. The aqueous extract was fractionated and halistanol trisulphate (24ε,25-dimethylcholestane-2β,3α,6α-triol trisodium sulphate) was isolated for the first time from P. citrina. Halistanol trisulphate had a bactericidal effect on exponentially growing S. aureus cells at the MIC (512 mg/L). Cytotoxicity biossays showed moderate toxicity against cancer cell line L929 (fibrosarcoma). This substance apparently acts by damaging the cell membrane, with subsequent cell lysis.
Halistanol trisulphate is a broad-spectrum antibiotic isolated from P. citrina with a mode of action involving disruption of the cytoplasmic membrane. It is a new candidate for research on antibacterial substances.
The early diagnosis of mycobacterial infections is a critical step for initiating treatment and curing the patient. Molecular analytical methods have led to considerable improvements in the speed and ...accuracy of mycobacteria detection.
The purpose of this study was to evaluate a multiplex polymerase chain reaction system using mycobacterial strains as an auxiliary tool in the differential diagnosis of tuberculosis and diseases caused by nontuberculous mycobacteria (NTM) RESULTS: Forty mycobacterial strains isolated from pulmonary and extrapulmonary origin specimens from 37 patients diagnosed with tuberculosis were processed. Using phenotypic and biochemical characteristics of the 40 mycobacteria isolated in LJ medium, 57.5% (n=23) were characterized as the Mycobacterium tuberculosis complex (MTBC) and 20% (n=8) as nontuberculous mycobacteria (NTM), with 22.5% (n=9) of the results being inconclusive. When the results of the phenotypic and biochemical tests in 30 strains of mycobacteria were compared with the results of the multiplex PCR, there was 100% concordance in the identification of the MTBC and NTM species, respectively. A total of 32.5% (n=13) of the samples in multiplex PCR exhibited a molecular pattern consistent with NTM, thus disagreeing with the final diagnosis from the attending physician.
Multiplex PCR can be used as a differential method for determining TB infections caused by NTM a valuable tool in reducing the time necessary to make clinical diagnoses and begin treatment. It is also useful for identifying species that were previously not identifiable using conventional biochemical and phenotypic techniques.
The Mycobacterium abscessus complex comprises multidrug-resistant, opportunistic, and rapidly growing pathogens responsible for severe infections. Here, we report the genome composition of four ...Mycobacterium abscessus subsp. massiliense isolates from three sources: two from the lung of a cystic fibrosis patient, one from a mammary cyst, and one from a gutter system.
Outbreaks of infections by rapidly growing mycobacteria following invasive procedures, such as ophthalmological, laparoscopic, arthroscopic, plastic, and cardiac surgeries, mesotherapy, and ...vaccination, have been detected in Brazil since 1998. Members of the Mycobacterium chelonae-Mycobacterium abscessus group have caused most of these outbreaks. As part of an epidemiological investigation, the isolates were typed by pulsed-field gel electrophoresis (PFGE). In this project, we performed a large-scale comparison of PFGE profiles with the results of a recently developed multilocus sequence typing (MLST) scheme for M. abscessus. Ninety-three isolates were analyzed, with 40 M. abscessus subsp. abscessus isolates, 47 M. abscessus subsp. bolletii isolates, and six isolates with no assigned subspecies. Forty-five isolates were obtained during five outbreaks, and 48 were sporadic isolates that were not associated with outbreaks. For MLST, seven housekeeping genes (argH, cya, glpK, gnd, murC, pta, and purH) were sequenced, and each isolate was assigned a sequence type (ST) from the combination of obtained alleles. The PFGE patterns of DraI-digested DNA were compared with the MLST results. All isolates were analyzable by both methods. Isolates from monoclonal outbreaks showed unique STs and indistinguishable or very similar PFGE patterns. Thirty-three STs and 49 unique PFGE patterns were identified among the 93 isolates. The Simpson's index of diversity values for MLST and PFGE were 0.69 and 0.93, respectively, for M. abscessus subsp. abscessus and 0.96 and 0.97, respectively, for M. abscessus subsp. bolletii. In conclusion, the MLST scheme showed 100% typeability and grouped monoclonal outbreak isolates in agreement with PFGE, but it was less discriminative than PFGE for M. abscessus.
The phylum Actinobacteria, which comprises a great variety of Gram-positive bacteria with a high G+C content in their genomes, is known for its large production of bioactive compounds, including ...those with antimicrobial activity. Among the antimicrobials, bacteriocins, ribosomally synthesized peptides, represent an important arsenal of potential new drugs to face the increasing prevalence of resistance to antibiotics among microbial pathogens. The actinobacterial bacteriocins form a heterogeneous group of substances that is difficult to adapt to most proposed classification schemes. However, recent updates have accommodated efficiently the diversity of bacteriocins produced by this phylum. Among the bacteriocins, the lantibiotics represent a source of new antimicrobials to control infections caused mainly by Gram-positive bacteria and with a low propensity for resistance development. Moreover, some of these compounds have additional biological properties, exhibiting activity against viruses and tumour cells and having also potential to be used in blood pressure or inflammation control and in pain relief. Thus, lantibiotics already described in Actinobacteria exhibit potential practical applications in medical settings, food industry and agriculture, with examples at different stages of pre-clinical and clinical trials.
The objective of this study was to identify the pattern of deposition of feces by supplemented crossbred dairy cows after the lactation peak on cultivated areas under levels of intensification of the ...system and its effects on nitrogen cycling, with the aid of geostatistics, in the rainy period. Treatments were composed of two levels of nitrogen fertilization (equivalent to 400 and 800 kg N/ha/year) and two types of animals, according to the daily milk production. Geostatistical and descriptive analyses of the data were conducted. The data presented positive coefficients of skewness and platykurtic kurtosis. For the coefficient of variation, there was elevated alteration, with rest areas showing higher values and paddocks with a higher level of fertilization showing lower values.The climate factors radiation, temperature and relative humidity significantly influenced the dispersion and location of feces. As to the degree of spatial dependence, the classification varied from moderated to strong. The range was from 14.0 to 12.7 m for the rest areas and paddocks, respectively. Fertilization and concentrate supply affected the deposition and loss of nitrogen via feces, elevating its values as the nutritional uptake is elevated. Fecal deposition showed heterogeneity, with areas of greater concentration such as shades, entrance of the paddocks and threshing floor, showing deposition peaks that reach 1,051.2 kg N/ha/year.
PDF
