Polycyclic aromatic hydrocarbons (PAHs) are compounds that can be quantified by fluorescence due to their high quantum yield. Haloalkalitolerant bacteria tolerate wide concentration ranges of NaCl and pH. They are potentially useful in the PAHs bioremediation of saline environments. However, it is known that salinity of the sample affects fluorescence signal regardless of the method. The objective of this work was to carry out a comparative study based on the sensitivity, linearity, and detection limits of the excitation, emission, and synchronous fluorescence methods, during the quantification of the residual anthracene concentration from the following haloalkalitolerant actinomycetes cultures Kocuria rosea, Kocuria palustris, Microbacterium testaceum, and 4 strains of Nocardia farcinica, in order to establish the proper fluorescence method to study the PAHs biodegrading capacity of haloalkalitolerant actinobacteria. The study demonstrated statistical differences among the strains and among the fluorescence methods regarding the anthracene residual concentration. The results showed that excitation and emission fluorescence methods performed very similarly but sensitivity in excitation fluorescence is slightly higher. Synchronous fluorescence using Δλ = 150 nm is not the most convenient method. Therefore we propose the excitation fluorescence as the fluorescence method to be used in the study of the PAHs biodegrading capacity of haloalkalitolerant actinomycetes.

Palabras clave: bacteria, emulsificante, tensoactivo, contaminación, biorremediación RESUMENUna opción para biorremediar ambientes salinos contaminados con compuestos orgá-nicos hidrofóbicos, es el uso de microorganismos haloalcalófilos o haloalcalotolerantes capaces de producir biosurfactantes estables y consumir al compuesto hidrófobo. El biosurfactante solubiliza al contaminante haciéndolo biodisponible para el microrganismo. De estudios previos se conocía la capacidad de siete actinobacterias haloalcalotolerantes para transformar el antraceno. En este trabajo, a estas siete más 11 más aisladas de ambientes salinos, se les determinó la capacidad para producir biosurfactantes con propiedades emulsificantes. A las que la mostraron, fueron seleccionadas para saber si utilizaban al antraceno como única fuente de carbono y energía. La capacidad para producir biosurfactante fue determinada por los métodos de actividad hemolítica, gota colapsada y difusión del diámetro de la gota. La propiedad emulsificante y la estabilidad de la emulsión se caracterizaron con el índice de emulsificación y el índice de emulsificación relativo, respectivamente. De 18 actinobacterias evaluadas, cinco cepas mostraron capacidad para producir biosurfactantes con propiedades emulsificantes, alta estabilidad en la emulsión y utilización de antraceno como única fuente de carbono y energía. De estas cinco, dos son haloalcalófilas pertenecientes a la especie Nocardiopsis salina y tres son haloalcalotolerantes pertenecientes a las especies: Kocuria palustris, Microbacterium testaceum y Kocuria rosea. En un estudio previo se determinó la capacidad transformadora de antraceno en las tres cepas haloalcalotolerantes, por lo tanto los resultados de este estudio sugieren proponerlas como candidatas para procesos de biorremediación de ambientes salinos contaminados con compuestos hidrófobos. Asimismo se sugiere determinar la misma capacidad para las dos cepas haloalcalófilas.

Atmospheric benzene and carbonyls were studied in San Nicolas de los Garza, Nuevo Leon, during 2011 and 2012. The relative abundance for measured VOCs was the following: formaldehyde (9.06 µg m −3 ) > acetaldehyde (8.06 µg m −3 ) > benzene (0.65 µg m −3 ). All measured VOCs had a clear seasonal trend with higher values of concentration during summer. Benzene and formaldehyde had a marked diurnal trend with the highest levels during morning, whereas acetaldehyde did not show a clear diurnal pattern. Meteorological analysis showed that the dominant winds came from NNE and ENE, suggesting that sources located in these directions contribute to the VOC levels. Principal component analysis (PCA) analysis revealed that photochemical activity influenced benzene and carbonyl levels during summer and that benzene was associated with vehicular traffic emissions during autumn and winter, showing good correlation with CO. Meteorological data showed that measured VOCs were influenced by regional sources. A health risk assessment showed that local exposure to carbonyls and benzene exceeded 1 × 10 −6 for integrated lifetime cancer risk. People living in San Nicolas de los Garza, thus, have a probable risk of suffering cancer in their lifetime. It is, therefore, necessary to improve environmental policies for controlling VOC levels in this area.

The intake of heavy metals through food consumption is a food safety problem that severely impacts the health of consumers, so information about food intake and heavy metal concentrations in food products is required to estimate the potential risk to the health of the population. The main purpose of this study was to estimate the potential risks to human health from exposure to Cd, Cu, Ni, Pb and Zn through the intake of Malus domestica Golden De

Diurnal variation of aromatic hydrocarbons (BTEX: benzene, toluene, ethylbenzene and p-xylene) in ambient air was determined in an urban site located in Monterrey, during North’s season 2020. Samples were collected using active sampling by a vacuum pump at a controlled flow of 200 ml/min during 1.5 h, considering three sampling periods: morning (07:00 - 08:30 h), midday (14:00 - 15:30 h) and afternoon (17:30- 19:00 h). Samples were desorbed with carbon disulfide and the extracts were analyzed by gas chromatography with ionization flame detection. Ethylbenzene and p-xylene were the dominant hydrocarbons (mean concentration: 18.581 g/m3 and 18.039 g/m3, respectively). Mean values for benzene and toluene were 15.137 g/m3 and 15.503 g/m3, respectively. All BTEX showed a diurnal pattern with higher values during the afternoon. From a meteorological study (wind roses) and chimiometric analysis (principal component analysis) were identified relations among the measured variables and their possible emission sources (industrial and vehicular sources). It was carried out a health risk assessment, considering both, carcinogenic and non-carcinogenic (respiratory and cardiovascular diseases) related to BTEX inhalation founding that population in the study site could develop cancer in the lifetime by benzene inhalation.