Caracterização de enterobactérias aderidas a partículas de plástico em galerias pluviais na orla de Fortaleza-Ceará

Abstract

Coastal cities face disorderly population growth with the lack of basic sanitation as one of the major environmental and public health problems. The discharge of sewage is one of the most common types of oceanic pollution and storm drains are specific vectors of this contamination in coastal cities. Due to inadequate disposal, it is estimated that 80% of plastic waste in the terrestrial environment ends up in the ocean. In the environment, these plastic wastes are degraded and become microplastics (PMs). It is known that in aquatic environments these particles are quickly colonized by microorganisms that form biofilms on their surfaces. This makes MPs hosts and dispersers of potentially pathogenic microorganisms. Thus, this work aimed to study the presence of enteric bacteria adhered to microplastics present in water and sand at the outlet of storm sewers, on the edge of Fortaleza/Ceará. The collections were carried out in three storm sewers: on Av. Rui Barbosa (P1), Av. Desembargador Moreira (P2) and Riacho Maceió storm sewers (P3). Samples of water and wet sand were collected at the outlets of these storm sewers. Five liters of water was filtered at each point to separate MPs particles. One water sample was collected separately for colimetry analysis. In the sand samples, the separation of the microplastic was done by density difference using sea water. The plastic microparticles separated from the samples were subjected to agitation in solution (Tween 80 1% + Sodium Pyrophosphate 1%) to disaggregate the bacterial cells. The washing was inoculated on MacConkey Agar selective medium and the grown colonies were isolated for identification through the IMVIC test and antibiogram. After processing, the MPs were washed and dried for further identification. Most Probable Number (MPN) of Escherichia coli bacteria in 100mL of water was 1,600 at the three sampled points. Sixty strains grown in selective medium, with Gram-negative morphology, were isolated. Fifty-six remained viable for biochemical tests. The bacteria have been identified as members of the Enterobacteriaceae family and belonging to the genera: Citrobacter, Yersinieae, Pseudomonas, Pantoea., Enterobacter, Hafnia, Klebsiella, Escherichia e Citrobacter. Enteric bacteria isolates showed resistance to nalidixic acid, ceftazidime, nitrofurantoin and amoxicillin + clavulanic acid. In the identification of microplastic particles, synthetic fibers, plastic fragments and a pellet were verified. The presence of enterobacteria aggregated to plastic microfragments dispersed in the coastal environment by the drainage of stormsewers and their role in the transport and protection of potential pathogens and resistance genes through water bodies to the marine environment was evidenced. Future studies on enteric bacterial dispersion and antimicrobial resistance should consider the ecological influence and consequences on coastal and marine ecosystems.