Abstract Bacterial strains were isolated from soil and aqueous solution samples from the Salar del Hombre Muerto, Argentina. A total of 141 strains were characterized and the tolerance to sodium chloride was evaluated. We performed a screening to search for molecules of biotechnological interest: carotenoids (11%), emulsifiers (95%), and exopolysaccharides (6%), and to assess the production of enzymes, including proteolytic (39%), lipolytic (26%), hemolytic (50%), and catalase activities (99%); 25 bacterial strains were selected for further studies. Some of them produced biofilms, but only Bacillus sp. HA120b showed that ability in all the conditions assayed. Although 21 strains were able to form emulsions, the emulsifying index Kocuria sp. M9 and Bacillus sp. V3a cultures were greater than 50% and, emulsions were more stable when the bacteria grew in higher salt concentrations. Only pigmented Kocuria sp. M9 showed lipolytic activity on olive oil medium and was able to produce biofilms when cultured without and with 4 M of NaCl. Yellow pigments, lipase activity, and biosurfactant production were observed for Micrococcus sp. SX120. Summarizing, we found that the selected bacteria produced highly interesting molecules with diverse industrial applications and, many of them are functional in the presence of high salt concentrations.

Resumen La velocidad de diseminación del COVID-19 en el mundo llevó a que los países afectados cerraran sus fronteras y tomaran medidas de distanciamiento social. Después de seis meses de que la enfermedad fuera declarada pandemia, muchos países están tomaron medidas de flexibilización del aislamiento, aunque sin una vacuna o un medicamento capaz de enfrentar la infección por el SARS-CoV-2, la situación podría revertirse en cualquier momento. El objetivo del presente trabajo fue proponer un algoritmo de decisión tendiente a optimizar las detecciones de casos asintomáticos y administrar la cuarentena de una manera estratégica, para así evitar la diseminación del virus y tender hacia una normalidad administrada. Se elaboró una propuesta tentativa de optimización y ordenamiento de pruebas de detección del SARS-CoV-2, basada en el análisis de muestras compuestas reunidas a partir de aquellas tomadas de manera individual a personas asintomáticas que integran cohortes de interés. Se definieron cohortes según su función en la sociedad o grado de vulnerabilidad. El algoritmo contempla variables como la prioridad de la cohorte, el número de integrantes de los grupos de análisis dentro de cada cohorte, el contacto intragrupal e intergrupal, la vulnerabilidad al contagio por la actividad desarrollada y el tiempo transcurrido desde que se realizó la prueba por última vez. Se ilustró la propuesta con cohortes hipotéticas definidas, con un único grupo de análisis para simplificar, y se comprobó que la aplicación de la herramienta permite establecer de una manera racional un orden de prioridad para realizar las pruebas en grupos críticos de la sociedad. Esta herramienta permitirá optimizar recursos y disminuir el impacto de la enfermedad en la salud, la sociedad y la economía de una región.

Abstract The rapid spread of COVID-19 throughout the world, has led most of the affected countries to close their borders and implement some form of lockdown. Six months after the pandemic started, many countries made decisions tending to relax the lockdown, although wit-hout a vaccine or treatment capable of confronting SARS-CoV-2 infection, the situation could be reversed at any time. In this context, the aim of this work was to propose a decision algorithm that will allow to optimize asymptomatic case detections and strategically manage quarantine to prevent the spread of the virus and drive the transition to a managed new normal. This tentative proposal was developed for optimizing and ordering the number of tests for the detection of SARS-CoV-2, analyzing composite samples (group analysis) combining with those samples individually taken from asymptomatic members of cohorts of interest. Cohorts were defined according to their critical role in society and/or their vulnerability. The algorithm includes variables such as cohort priority, number of cohort members in the analysis groups, intra-and intergroup contact, vulnerability to contagion due to the activity performed, and time elapsed since last testing. The proposed tool was illustrated with defined hypothetical cohorts, in which, for the sake of simplification, only one analysis group was considered. The application of this tool allowed to establish in a rational way a priority order to test critical groups in society. Furthermore, this tool would help to optimize resources, reducing the impact on a region’s health, society, and economy.

Abstract Random amplified polymorphic DNA-PCR (RAPD-PCR) is a technique successfully used to generate characteristic fingerprints of different bacteria. Bacillus is a genus that includes heterogeneous species, thus a combination of different techniques is essential for their identification. Here we used RAPD-PCR methodology to distinguish among genetically similar strains and to evaluate the genetic diversity of Bacillus species from the Salar del Hombre Muerto, in the Northwest of Argentina. The RAPD-PCR used allowed obtaining different amplification profiles for each Bacillus species and strains. By comparing the fingerprint profiles, we could observe that some of the salt flat isolates showed similar profiles than identified strains. As expected, the bacilli group isolated revealed a wide heterogeneity. RAPD-PCR was found to be a quick and reliable technique to evaluate the diversity of Bacillus strain and was successfully applied to characterize the genetic diversity present in the Salar del Hombre Muerto.

O objetivo deste estudo foi comparar a detecção de DNA de Trypanosoma cruzi por PCR em tempo real (qPCR) e PCR convencional no sangue periférico (N=25) e músculo esquelético (N= 20) de camundongos tratados com medicamentos tripanomicidas depois de 6 meses de pós-tratamento. Nas amostras de sangue foi detectado um total de sete positivas por qPCR; enquanto que apenas foram encontradas 2 por PCR convencional. No músculo esquelético, 15 amostras foram positivas por qPCR e 3 por PCR convencional. Os resultados mostram que a força de concordância é fraca entre as técnicas de PCR utilizadas para a detecção de DNA de T. cruzi (k=0,37, 49% positivas por qPCR vs. 11% para a PCR convencional, p=0,0001). Nas amostras de sangue, os valores diagnósticos de qPCR em relação a PCR convencional foram de 100% sensibilidade; 78% de especificidade; 30% de VPP; 100% VPN; 4,6 RVP; 0 RVN. Para as amostras de músculo esquelético, os seguintes valores diagnósticos de qPCR foram obtidos: 100% sensibilidade; 29% de especificidade; 20% de VPP; 100% VPN; 1,4 RVP; 0 RVN. Ambas as técnicas são igualmente sensíveis na faixa de concentração média-alta, mas qPCR foi mais eficaz na detecção de baixas cargas parasitárias, especialmente em amostras de tecido.

The aim of this work was to compare detection of Trypanosoma cruzi DNA by real time (qPCR) and conventional PCR in peripheral blood (n=25), and skeletal muscle (n=20) of mice treated with trypanocidal compounds after 6 months post-treatment. A total of 7 blood samples were positive by qPCR; whereas, by conventional PCR only 2 were detected. In skeletal muscle, 15 samples were regarded positive by qPCR and 3 by conventional PCR. These results showed a weak concordance strength among PCR techniques employed to detect T. cruzi DNA in the studied samples (k=0.37; 49% positives by qPCR vs. 11% by conventional PCR, p=0.0001). In blood samples, qPCR diagnostic values in comparison with conventional PCR were: 100% sensibility; 78% specificity; 30% PPV; 100% NPV; 4.6 PVR; 0 NVR. For skeletal muscle samples, qPCR diagnostic values were: 100% sensibility; 29% specificity; 20% PPV; 100% NPV; 1.4 PVR; 0 NVR. Both techniques were equally sensitive in the medium-high concentration range, but qPCR was more effective to detect low parasitic burden, particularly in skeletal muscle samples.

El objetivo del presente trabajo fue comparar la detección de ADN de Trypanosoma cruzi mediante PCR en tiempo real (qPCR) y PCR convencional en sangre periférica (n=25) y músculo esquelético (n=20) de ratones tratados con drogas tripanomicidas luego de 6 meses post-tratamiento. En las muestras de sangre se detectaron un total de 7 positivas por qPCR, mientras que por PCR convencional sólo se detectaron 2. En músculo esquelético, 15 muestras fueron positivas por qPCR y 3 por PCR convencional. Los resultados obtenidos demuestran que la fuerza de concordancia es débil entre las técnicas de PCR utilizadas para la detección de ADN de T. cruzi (k=0,37; 49% positivas por qPCR vs. 11% por PCR convencional, p=0,0001). En las muestras de sangre, los valores diagnósticos de qPCR con respecto a la PCR convencional fueron: 100% sensibilidad; 78% especificidad; 30% VPP; 100% VPN; 4,6 RVP; 0 RVN. Para las muestras de músculo esquelético se obtuvieron los siguientes valores diagnósticos de qPCR: 100% sensibilidad; 29% especificidad; 20% VPP; 100% VPN; 1,4 RVP; 0 RVN. Ambas técnicas fueron igualmente sensibles en el rango de mediana-alta concentración, pero qPCR fue más efectiva para detectar bajas cargas parasitarias, en particular en las muestras de tejido.