Cadmium is a major heavy metal found in polluted aquatic environments, mainly derived from industrial production processes. We evaluated the biosorption of solubilized Cd²⁺ using the extracellular polymeric substances (EPS) produced by Bacillus sp. MC3B-22 and Microbacterium sp. MC3B-10 (Microbactan); these bacteria were originally isolated from intertidal biofilms off the coast of Campeche, Mexico. EPS were incubated with different concentrations of cadmium in ultrapure water. Residual Cd²⁺ concentrations were determined by Inductive Coupled Plasma-Optic Emission Spectrometry and the maximum sorption capacity (Qmax) was calculated according to the Langmuir model. EPS were characterized by X-ray photoelectron spectroscopy (XPS) before and after sorption. The Qmax of Cd²⁺ was 97 mg g⁻¹ for Microbactan and 141 mg g⁻¹ for MC3B-22 EPS, these adsorption levels being significantly higher than previously reported for other microbial EPS. In addition, XPS analysis revealed changes in structure of EPS after biosorption and showed that amino functional groups contributed to the binding of Cd²⁺, unlike other studies that show the carbohydrate fraction is responsible for this activity. This work expands the current view of bacterial species capable of synthesizing EPS with biosorbent potential for cadmium and provides evidence that different chemical moieties, other than carbohydrates, participate in this process.

Coastal zones support fisheries that provide food for humans and feed for animals. The decline of fisheries worldwide has fostered the development of aquaculture. Recent research has shown that extracellular polymeric substances (EPS) synthesized by microorganisms contribute to sustainable aquaculture production, providing feed to the cultured species, removing waste and contributing to the hygiene of closed systems. As ubiquitous components of coastal microbial habitats at the air–seawater and seawater–sediment interfaces as well as of biofilms and microbial aggregates, EPS mediate deleterious processes that affect the performance and productivity of aquaculture facilities, including biofouling of marine cages, bioaccumulation and transport of pollutants. These biomolecules may also contribute to the persistence of harmful algal blooms (HABs) and their impact on cultured species. EPS may also exert a positive influence on aquaculture activity by enhancing the settling of aquaculturally valuable larvae and treating wastes in bioflocculation processes. EPS display properties that may have biotechnological applications in the aquaculture industry as antiviral agents and immunostimulants and as a novel source of antifouling bioproducts.

Water contamination is a phenomenon of global concern resulting from human activities. Coliform bacteria reduce water quality and negatively affect public health. The pollution of surface and groundwater by coliform bacteria, including Escherichia coli , originate, in general, from point sources of pollution derived from human settlements, such as those located in Module I-1, Irrigation District 035, La Antigua, Veracruz, Mexico. The objective of this study was to assess the level of contamination of surface and groundwater by coliform bacteria and E. coli , as well as to identify point sources of water contamination by these bacteria in the sugarcane agroecosystem of Irrigation Module I-1, La Antigua. Sampling sites included deep wells, irrigation canals and natural streams near point sources of pollution. The determination of total coliform bacteria and E . coli were made in accordance with Mexican Standard NMX-AA-042-1987. Total coliform results revealed differences between groundwater (198.6 MPN/100 mL) and surface water concentrations (52,419.2 MPN/100 mL) (p < 0.05), and between irrigation water (76,501.1 MPN/100 mL) and concentrations in natural streams (28,337.3 MPN/100 mL). The highest concentration of E. coli was found in groundwater and surface water samples from the municipality of La Antigua. The primary sources of contamination are the discharges from drains and septic tanks. Total coliform values exceeded permissible limits established by NOM-127-SSA1-1994 that regulates the permissible water quality limits for human use and consumption. The presence of E. coli represents a significant public health risk.

El Paraquat es un herbicida utilizado en la actividad agropecuaria para controlar hierbas, su modo de acción es por medio de contacto y no selectivo. Debido a su alta solubilidad en agua y baja volatilidad representa un riesgo potencial para organismos acuáticos, principalmente los que son cultivados con aguas superficiales que reciben impacto de la actividad agrícola. La tilapia Oreochromis niloticusy el langostino Macrobrachium olfersiison organismos de importancia comercial para la industria acuícola del estado de Veracruz, México.El objetivo de este estudio fue determinar la Concentración Letal Media (CL50) del herbicida Dasurquat® (ingrediente activo Paraquat) a través de un bioensayo de toxicidad aguda (96 horas). Se utilizaron como especímenes de prueba a juveniles de tilapia O. niloticus(peso promedio = 10 mg, longitud total= 8,75 mm) y otro el ensayo fue con poslarvas de langostino M. olfersii(peso promedio = 5 mg, longitud total= 5,72 mm). Se emplearon cinco concentraciones (5, 10, 20, 40 y 80 µl L-1para el bioensayo con juveniles de tilapia; para el bioensayo con poslarvas de langostino las concentraciones fueron 0,1, 0,2, 0,5, 0,7 y 1 µl L-1). El diseño experimental consideró un control negativo, con dos repeticiones y dos réplicas por cada tratamiento. El análisis de datos se realizó con el método Probit para determinar la CL50a 96 horas, se obtuvo un valor para juveniles de O. niloticusde 17,49 µl L-1con intervalo de confianza (95 %) con límite inferior de 13,75 µl L-1y límite superior 22,25 µl L-1, para las larvas de M. olfersiise obtuvo un valor de 0,31 µl L-1con intervalo de confianza (95 %) con límite inferior de 0,26 µl L-1y límite superior 0,35 µl L-1. El análisis de varianza demostró que no existió diferencia estadística significativa (p > 0.05) entre las réplicas de los tratamientos. Se concluye que es necesario continuar con estudios para evaluar su toxicidad en organismos acuáticos debido al amplio uso de este herbicida en la actividad agropecuaria, y determinar su riesgo para otras actividades productivas además de la acuicola.