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Las plantas de tratamiento de agua residual, son sistemas diseñados con el objetivo de disminuir la carga contaminante del agua residual doméstica e industrial, mediante una serie de procesos físicos, químicos y biológicos produciendo efluentes de mejor calidad. El principal subproducto del tratamiento de aguas residuales son los lodos provenientes de los tratamientos primarios y secundarios. Dependiendo del sistema de tratamiento de aguas residuales y del manejo de los lodos generados en la planta, será la calidad de los lodos. Se ha determinado que en Colombia los lodos no presentan elevadas cantidades de metales pesados, no obstante, presentan grandes cantidades de microorganismos patógenos que pueden convertirse en un riesgo para la salud y el medio ambiente. Los lodos tienen que ser estabilizados para poder ser reutilizados como biosólidos. La estabilización comprende tratamientos que disminuyen las concentraciones de microorganismos patógenos. La selección del tratamiento para la estabilización del lodo depende de varios facto- res, tales como: la cantidad y calidad de lodos a tratar, las condiciones particulares del sitio y la situación financiera para esta disposición. En Colombia se han aplicado diferentes tratamientos de estabilización como la estabilización alcalina, deshidratación en el lecho de secado, entre otros. Cada tratamiento tiene sus ventajas y desventajas. En Colombia son pocos los estudios y a baja escala, donde se eviden- cia la aplicación de biosólidos a nivel agrícola. Sin embargo, los es- tudios han indicado que los biosólidos se pueden aplicar en el suelo mejorando su estructura y fertilidad, aumentando el rendimiento de los cultivos y produciendo alimentos inocuos con similares características organolépticas y nutricionales que los cultivos tradicionales.

The objective of this work was to evaluate the microbiological quality of cheese produced by formal and informal micro-enterprises in Paipa, Colombia, to isolate potentially pathogenic bacteria and to determine their prevalence and resistance to antimicrobials such as antibiotics and biocides. Sixteen micro-enterprises of the seventy existing in the region were sampled during 3 years. Viable concentrations of aerobic mesophiles, total and fecal coliforms, Salmonella sp., Listeria monocytogenes, Staphylococcus sp., yeasts, and molds were determined. Seventy-three bacterial isolates were identified by 16S rRNA gene sequencing. The susceptibility of the isolates to antibiotics and biocides was determined. The results indicated that between 98 and 100% of the cheese samples (n = 48 samples) of formal and informal micro-enterprises presented populations of total and fecal coliforms and Staphylococcus sp. above the limits established by Colombian regulations and varied according to the micro-enterprise. The results also indicated that 56% of Staphylococcus isolates were S. aureus. L. monocytogenes was positive in 38% of the samples. Salmonella sp. was not detected. The coliforms that prevailed were Escherichia coli (25%), Citrobacter freundii (14%), and Proteus mirabilis (8%). All L. monocytogenes were sensitive to ampicillin but resistant to erythromycin and trimethoprim-sulfamethoxazole. S. aureus isolates were susceptible to most antibiotics, except tetracycline and erythromycin (7% resistance). Likewise, 30% of coliforms (n = 36) were multidrug-resistant to antibiotics but susceptible to biocides.

Las bacteriocinas son péptidos sintetizados por bacterias que presentan un amplio potencial como conservador de alimentos. Son una buena alternativa para reemplazar los aditivos químicos y producir alimentos mínimamente procesados. Las bacteriocinas que se han estudiado con mayor interés en la industria alimentaria son las derivadas de bacterias ácido-lácticas (bal) porque tienen el estatus Generally Regarded As Safe (gras). No obstante, se ha determinado que las bacteriocinas tienen ciertas desventajas a la hora de aplicarlas en los alimentos, especialmente en derivados lácteos. Esas desventajas pueden enmendarse al combinar las bacteriocinas con otros tratamientos emergentes en la industria alimentaria. El objetivo de esta revisión fue realizar un análisis sobre las principales bacteriocinas utilizadas y su efecto sinérgico contra bacterias patógenas y/o alteradoras, cuando se aplican de manera combinada con otros tratamientos como sustancias químicas, sistema lactoperoxidasa, altas presiones hidrostáticas, nanopartículas, bacteriófagos y aceites esenciales. Los resultados de esta revisión indican que cuando se aplican las bacteriocinas con otros tratamientos pueden aumentar la actividad antimicrobiana, lo cual mejoraría la seguridad alimentaria. Se concluye que las mejores combinaciones del uso de las bacteriocinas y tecnologías emergentes son bacteriocinas y nanopartículas y bacteriocinas con bacteriófagos, cuyas combinaciones inhiben el crecimiento tanto de bacterias Gram positivas como de Gram negativas, entre las ventajas están, fáciles de aplicar en los alimentos, pueden ser de bajo costo, no cambian las características sensoriales del producto, permiten combatir la resistencia antimicrobiana, y destruyen completamente a los microorganismos sin darles oportunidad de recuperación durante el periodo de maduración o almacenamiento.

Wastewater sludge is a by-product of waste water treatment; it is often employed in agricultural processes following appropriate microbiological stabilization. In this study, we evaluated two methods of sludge stabilization in the waste water treatment plant of Sotaquirá, Colombia. The two assessed stabilization methods were dewatering on drying beds and alkaline stabilization. The stabilization through dewatering on drying bed was carried out for five months. Alkaline stabilization was conducted for 96 hours with three concentrations of calcium oxide, 7%, 9%, and 13% w/w. Humidity, pH, organic carbon, phosphorus, organic nitrogen, fecal coliforms, somatic phages, total helminth eggs, and Salmonella sp. were monitored monthly for the sludge under dewatering treatment and at 0, 12, 24 hours for sludge under alkaline stabilization treatment. Both treatments succeded in eliminating Salmonella sp. Helminth eggs were eliminated by alkaline stabilization, whereas it was reduced to one or zero helminth eggs with the dewatering treatment. Somatic phages were eliminated with alkaline stabilization but were only reduced to 3.52 log CFU/g with the dewatering method. Dewatering on drying beds produced biosolids that can be used for soil restoration. Whereas alkaline stabilization produced biosolids that can be used for agricultural purposes. Alkaline stabilization with 9% and 13 % calcium oxide ostensibly reduced nitrogen and phosphorus contents in the sludge, whereas 7 % calcium affected less the phosphorus concentration of the sludge. These results indicate that sludge dewatering on drying beds is an effective sludge sanitation protocol to be implemented in small waste water treatment plants, such that in Sotaquirá, Colombia.

S- and Fe-cycling bacteria can decisively affect the crystallization of Fe-bearing minerals in sediments from fluvial environments. We have studied the relationships between the Fe-bearing mineral assemblage and the bacterial community composition in the sediments rich in organic matter from the upper Chicamocha river basin (Colombia). Rapid flowing sections of the river contain sediments that have a high redox potential, are poor in organic matter and are enriched in kaolinite and quartz. On the other hand, the mineral assemblage of the sediments deposited in the La Playa dam with a high content in organic matter is enriched in Fe-bearing minerals: (a) vivianite and pyrite in the permanently flooded sediments of the dam and (b) pyrite and goethite in the periodically emerged sediments. The bacterial community composition of these sediments reveals anthropic organic matter pollution processes and biodegradation associated with eutrophication. Moreover, periodically emerged sediments in the La Playa dam contain bacterial groups adapted to the alternation of dry and wet periods under oxic or anoxic conditions. Cell-shaped aggregates with a pyritic composition suggest that sulfate-reducing bacteria (SRB) communities were involved in the precipitation of Fe-sulfides. The precipitation of vivianite in the flooded sediments was favored by a greater availability of Fe(II), which promoted the iron-reducing bacteria (IRB) enrichment of the sediments. The presence of sulfur-oxidizing bacteria (SOB) in the flooded sediments and the activity of iron-oxidizing bacteria (IOB) in the periodically emerged sediments favored both pyrite crystallization under a high sulfide availability and the oxidation of microbially precipitated monosulfides. Moreover, IOB enhanced goethite formation in the periodically emerged sediments.

We studied the relationships between the trace element concentration in sediments from a saline lake at a tropical latitude (Sochagota Lake, Colombia) containing hydrothermal and anthropic inputs with the organic matter content, the mineral assemblage composition and the activity of the bacterial communities of the sediments. Organic matter-poor sediments (TOC

Background: Paipa cheese is a traditional, semi-ripened cheese made from raw cow&rsquo, s milk in Colombia. The aim of this work was to gain insights on the microbiota of Paipa cheese by using a culture-independent approach. Method: two batches of Paipa cheese from three formal producers were sampled during ripening for 28 days. Total DNA from the cheese samples was used to obtain 16S rRNA gene sequences by using Illumina technology. Results: Firmicutes was the main phylum found in the cheeses (relative abundances: 59.2&ndash, 82.0%), followed by Proteobacteria, Actinobacteria and Bacteroidetes. Lactococcus was the main genus, but other lactic acid bacteria (Enterococcus, Leuconostoc and Streptococcus) were also detected. Stapylococcus was also relevant in some cheese samples. The most important Proteobacteria were Enterobacteriaceae, Aeromonadaceae and Moraxellaceae. Enterobacter and Enterobacteriaceae (others) were detected in all cheese samples. Serratia and Citrobacter were detected in some samples. Aeromonas and Acinetobacter were also relevant. Other minor genera detected were Marinomonas, Corynebacterium 1 and Chryseobacterium. The principal coordinates analysis suggested that there were producer-dependent differences in the microbiota of Paipa cheeses. Conclusions: lactic acid bacteria are the main bacterial group in Paipa cheeses. However, other bacterial groups, including spoilage bacteria, potentially toxin producers, and bacteria potentially pathogenic to humans and/or prone to carry antimicrobial resistance genes are also relevant in the cheeses.

Carbaril (1-naftil N-metilcarbamato) es un plaguicida perteneciente al grupo de los N- metilcarbamatos, se caracteriza por ser muy tóxico y moderadamente persistente en el medio ambiente, es utilizado extensivamente para el control de plagas en diferentes cultivos. Existen factores bióticos y abióticos que afectan el destino final de Carbaril en el ambiente. Se han reportado diferentes vías de degradación de este plaguicida, determinando que las bacterias son las principales degradadoras. El estudio de las vías de degradación es importante, debido a que muchos de los metabolitos podrían llegar a ser más tóxicos que el compuesto parental. La presente revisión busca establecer las rutas de degradación de Carbaril, los principales metabolitos y su impacto en el medio ambiente.

El objetivo de este trabajo fue caracterizar bacterias oxidadoras de amonio (BOA) aisladas del humedal de flujo subsuperficial de la planta de tratamiento de aguas residuales de la Universidad de Boyacá. Para ello, se realizaron diluciones de muestras de suelo, las cuales fueron enriquecidas con caldo amonio e incubadas durante 28 días a 30ºC. De los tubos con reacción positiva para nitritos, se aislaron bacterias en medio mínimo de sales minerales con amonio como única fuente de nitrógeno. Se obtuvieron 16 aislamientos, los cuales se caracterizaron macroscópica, microscópica, y bioquímicamente. De los 16 aislamientos obtenidos, tan solo 4 tuvieron la capacidad de crecer rápidamente en medio amonio sólido, durante 28 días a 30ºC. Estos aislamientos fueron evaluados por su capacidad de oxidar el amonio a nitrito en medio mínimo de sales minerales. Los resultados indicaron que el aislamiento A7 y A15, presentaron diferencias significativas en la oxidación del amonio con respecto a los demás aislamientos seleccionados, lo cual indica su potencial para ser utilizado en procesos de tratamiento de aguas residuales.

The sludge produced in wastewater treatment plants constitutes a potential alternative to replace traditional fertilizers and reduce costs in agricultural activities. The objective of this work was to compare the fertilizing effect of the sludge produced in the wastewater treatment plant of Sotaquirá-Colombia, with the fertilizers traditionally used on the tomato crop (Solanum lycopersicum L). For this, the sludge was previously stabilized with two different treatments: dehydration and the addition of CaO. Subsequently, four treatments were applied to the tomato seedlings, 135 g.kg-1 of dehydrated biosolid, 135 g.kg-1 biosolid stabilized with CaO, 135 g.kg-1 of ABIMGRA®, 135 g.kg-1 of naturcomplet®-G, and greenhouse soil without biosolids. The height of the plant, the fresh and dry mass, foliar area, and fruits per plant, were measured at 0, 30, 60 and 90 days after sowing. In tomato fruits, the concentrations of heavy metals, coliforms, helminth eggs, somatic phages, and Salmonella sp., were determined. The dehydrated biosolids had a significant effect on the size, the fresh mass, foliar area, and the number of fruits per plant, compared to the alkaline biosolids. The dry mass of the plants (120 g. plant-1) was similar to traditional fertilizers and biosolids. Tomatoes produced with biosolids had low levels of heavy metals and an absence of pathogenic microorganisms. In conclusion, the biosolid obtained by dehydration in Sotaquirá can be used as a potential fertilizer in tomato cultivation.