Beach water quality is an important factor concerning public health and tourism linked to the “Sun, Sea and Sand” market and is usually assessed in international regulations by the quantification of Escherichia coli and enterococci counts. Despite Salmonella spp. detection not being included in international normative, the presence/absence of this bacteria is also an indicator of seawater quality. The objective of this study was to determine microbiological quality of beach water at 14 beaches along the Department of Atlántico (Colombia) and its relationship with beach characteristics as beach typology (i.e., urban, village, rural and remote areas), presence of beach facilities (e.g., bars, restaurants, etc.) and streams outflowing into the coastline. Sampling program aimed to analyse E. coli and Salmonella spp., by culture-based and real time PCR methods, respectively. Microbiological outcomes were compared with beach characteristics, and a cluster analysis was performed. E. coli and Salmonella spp. were detected in 70% and 20% of samples, respectively. Highest E. coli counts were observed at beaches classified as urban and at Sabanilla, a rural beach with presence of numerous beach restaurants/bars. Salmonella spp. presence was associated with streams that lack wastewater treatment systems. Cluster analysis clearly evidenced the relationship between E. coli and Salmonella spp. and beach characteristics, allowing to obtain indications to implement management programs. According to data obtained, monitoring programs have to be especially carried out in urban areas and at places with beach facilities. This could enhance microbiological water quality and consequently, beachgoers safety and touristic beach attractiveness to international visitors.

The mangrove ecosystems of the Department of Atlántico (Colombian Caribbean) are seriously threatened by problems of hypersalinization and contamination, especially by heavy metals from the Magdalena River. The mangrove plants have developed various mechanisms to adapt to these stressful conditions, as well as the associated microbial populations that favor their growth. In the present work, the tolerance and detoxification capacity to heavy metals, especially to mercury, of a halotolerant endophytic bacterium isolated from the species Avicennia germinans located in the Balboa Swamp in the Department of Atlántico was characterized. Diverse microorganisms were isolated from superficially sterilized A. germinans leaves. Tolerance to NaCl was evaluated for each of the obtained isolates, and the most resistant was selected to assess its tolerance to Pb²⁺, Cu²⁺, Hg²⁺, Cr³⁺, Co²⁺, Ni²⁺, Zn²⁺, and Cd²⁺, many of which have been detected in high concentrations in the area of study. According to the ANI and AAI percentages, the most halotolerant strain was identified as Priestia flexa, named P. flexa 7BS3110, which was able to tolerate up to 12.5% (w/v) NaCl and presented a minimum inhibitory concentrations (MICs) of 0.25 mM for Hg, 10 mM for Pb, and 15 mM for Cr³⁺. The annotation of the P. flexa 7BS3110 genome revealed the presence of protein sequences associated with exopolysaccharide (EPS) production, thiol biosynthesis, specific proteins for chrome efflux, non-specific proteins for lead efflux, and processes associated with sulfur and iron homeostasis. Scanning electron microscopy (SEM) analysis showed morphological cellular changes and the transmission electron microscopy (TEM) showed an electrodense extracellular layer when exposed to 0.25 mM Hg²⁺. Due to the high tolerance of P. flexa 7BS3110 to Hg²⁺ and NaCl, its ability to grow when exposed to both stressors was tested, and it was able to thrive in the presence of 5% (w/v) NaCl and 0.25 mM of Hg²⁺. In addition, it was able to remove 98% of Hg²⁺ from the medium when exposed to a concentration of 14 mg/L of this metalloid. P. flexa 7BS3110 has the potential to bioremediate Hg²⁺ halophilic contaminated ecosystems.

Introducción. Cada año mueren, aproximadamente, tres millones de personas como consecuencia de las enfermedades transmitidas por alimentos. El queso artesanal fresco que se produce y distribuye en la región Caribe colombiana es un producto autóctono de los departamentos de Córdoba, Sucre, Bolívar, Atlántico, Magdalena, Cesar y La Guajira. Su consumo masivo aumenta el riesgo de infección con salmonelosis, listeriosis y brucelosis debido a que es elaborado con una tecnología muy rústica, con leche de vaca no pasteurizada, sin procedimientos estandarizados e higiénicos, y a que su almacenamiento no es adecuado.Objetivo. Detectar la presencia de Salmonella spp., Listeria spp. y Brucella spp. en muestras de queso artesanal costeño fresco procedente de los departamentos de la región Caribe colombiana.Materiales y métodos. Mediante reacción en cadena de la polimerasa en tiempo real (qPCR), se analizaron 27 muestras de queso proveniente de cinco departamentos de la región Caribe: Atlántico (n=6), Bolívar (n=2), Córdoba (n=1), Magdalena (n=16) y Sucre (n=2). Del total de las muestras, 17 eran de queso blando, cinco de queso semiduro y cinco de queso duro.Resultados. En el 62,9 % de las muestras se detectó Salmonella spp. (17/27), en el 70,4 %, Listeria spp. (19/27), y en el 22,2 %, Brucella spp. (6/27). Las muestras provenían principalmente del departamento del Magdalena y, en 62,5 % (10/16) de ellas, se encontró Salmonella spp. y Listeria spp., en tanto que en el 50 % (3/6) de las muestras del departamento del Atlántico se detectó Brucella spp. Conclusión. Los resultados evidenciaron la presencia de estos microorganismos en todas las muestras de queso costeño blando.

Beaches represent important economic resources linked to “Sun, Sea and Sand” tourism and, therefore, their water quality constitutes an issue of great relevance especially in developing countries. The main objective of this work was to determine the microbial quality of beach sediments along the Caribbean coast of the Department of Atlántico (Colombia) and its relationships with the existence of local sources of contamination (e.g., streams containing wastewaters), beach exposition to waves, the quantity of beach visitors—which is reflected by beach typology (e.g., urban, rural, etc.), the presence of tourist activities/infrastructures and the beach sand sedimentological characteristics. Along the study area, samples of beach sediments were gathered in beach face and backshore areas at 11 sectors and the microbiological counts of three faecal indicator bacteria, i.e., Escherichia coli, Enterococcus spp. and Clostridium perfringens, were determined. A homogeneous distribution was recorded along the coast of Escherichia coli and Clostridium perfringens in both beach face and backshore sediments, in the order of 5 and 2 log CFU/100 mL, respectively; Enterococcus spp. was, at places, not observed in backshore sediments. No relationships existed between, on one side, the counts of the faecal indicator bacteria considered and, on the other side, the presence of streams and tourist activities/infrastructures, beach typology, exposition to waves and the sedimentological characteristics of beach sands. Such results suggest a chronic contamination of beach face and backshore sediments linked to the heavily polluted sedimentological load of the Magdalena River.

Avicennia germinans, a representative of the marine coastal mangrove ecosystem, vital in the Colombian Caribbean, harbors a unique microbial diversity that could contain microorganisms with the potential to promote plant growth of agricultural species such as maize. The objective of this research was to evaluate A. germinans endophytes at different sampling sites and in diverse plant organs in order to identify the growth-promoting role of the most sodium chloride-tolerant endophyte found. These were then inoculated in maize seeds under drought stress conditions simulated by polyethylene glycol (PEG) in vitro. To this end, samples of adult A. germinans plants were collected from four mangrove ecosystems in the Colombian Caribbean. Several isolates were able to tolerate up to 15% NaCl (w/v), produce indole-3-acetic acid (IAA), show proteolytic activity, and inhibit phytopathogenic fungi. The best-performing strain, C1T-KM1901-B, was genomically identified as Bacillus paralicheniformis and evaluated as a bioinoculant in maize seeds under PEG-induced drought stress. Inoculation with B. paralicheniformis significantly increased germination potential and germination index of drought-resistant seeds compared to non-inoculated controls under severe drought stress conditions (40% PEG). In addition, inoculated seedlings exhibited significantly higher roots and shoot fresh and dry biomass at moderate to severe drought stress levels (15% and 20% PEG). These results are position B. paralicheniformis C1T-KM1901-B, isolated from Avicennia germinans, as a promising bioinoculant to enhance maize establishment under drought conditions.