Toxic concentrations of metronidazole to Microcystis protocystis

Abstract

Antimicrobials are among the most commonly used drugs and have become a class of contaminants with great environmental importance. Metronidazole is an antimicrobial used for the therapeutic management of several human diseases. The toxicity of antimicrobials on aquatic species may affect sensitive microorganisms and reduce metabolic processes. Cyanobacteria is a group of organisms that are of great ecological importance in aquatic environments. Studies indicate that cyanobacteria are very sensitive to some antimicrobials. Therefore, it is necessary to evaluate the effects of metronidazole contamination on phytoplankton. The aim of this study was to investigate the effects of metronidazole on the growth of the cyanobacterium Microcystis protocystis and to evaluate the stability of this antimicrobial agent in the culture medium over a period of 96 hours. M. protocystis was resistant to growth inhibition by metronidazole. The EC50 of this antimicrobial for M. protocystis was 117.3 mg L -1 . Under the growth inhibition test conditions, neither a significant change in the MNZ concentration nor the presence of drug metabolites or degradation products was observed. These results indicate low cellular uptake of the antimicrobial agent and its persistence in the culture medium.Keywords: antimicrobials, toxicity, metronidazole, cyanobacterium, Microcystis protocystis. Concentrações tóxicas de metronidazol para Microcystis protocystis ResumoAntimicrobianos estão entre os fármacos mais usados e tem se tornado uma classe emergente de contaminantes com grande importância ambiental. A toxicidade dos antimicrobianos sobre as espécies aquáticas podem afetar microrganismos sensíveis e reduzir seus processos metabólicos. O Metronidazol é um antimicrobiano usado para o manejo terapêutico de várias doenças humanas. Cyanobacteria é um grupo de organismos de grande importância ecológica no ambiente aquático. O estudo visou investigar os efeitos do metronidazol-MNZ sobre o crescimento da cianobactéria Microcystis protocystis e avaliar a persistência do antimicrobiano no meio de cultivo durante 96h. A M. protocystis mostrou-se resistente à inibição de crescimento pelo MNZ. A EC 50% do MNZ para a espécie foi 117,3 mg L -1 . Nas condições do teste de inibição de crescimento não foi observada variação significativa da concentração de MNZ nem a presença de metabólitos ou produtos de degradação do fármaco, indicando baixa captação celular do antimicrobiano e sua persistência no meio de cultivo.Palavras chave: antimicrobiano, toxicidade, metronidazol, cianobactéria, Microcystis protocystis.

Rare occurrence of nine Microcystis species (Chroococcales, Cyanobacteria) in a single lake (Lake Dojran, fYR Macedonia)

“…Till now, this species was reported as a true element of plankton in karst environments of the Yucatán peninsula, Mexico (López-Adrián & Barrientos-Medina, 2007;Tavera et al, 2013) which are rich in tropical species of cyanobacteria. This species was also reported on several localities in Brazil: in São Paulo State (Sant'Anna et al, 2004), in the Cordeiro, Camalau and Acauã Reservoirs (Vasconcelos et al, 2013) and in Minas Gerais State (Magalhães et al, 2014). It was also found in the neo-tropical, eutrophic reservoir Riogrande II in Colombia (Palacio et al, 2015), but still, up to our knowledge, it was never reported for Europe.…”

Effect of PHRs and PCPs on Microalgal Growth, Metabolism and Microalgae-Based Bioremediation Processes: A Review

“…For Desmodesmus / Scenedesmus strains, metronidazole (within 7.8–125 μg/L) caused 50% inhibition of photosynthetic activity in Desmodesmus subspicatus culture [83], but in another study, at 705 mg/L, caused 50% inhibition to Scenedesmus vacuolatus [50]. For the cyanobacterium Microcystis protocystis , high resistance (50% inhibition at 117 mg/L) to metronidazole was reported [124].…”

Synthesis of the mesostructured polymer-silica composite and silicon dioxide through polymer swelling in silica precursor

“…Unfortunately, beyond high efficiency and high solubility in water, this drug is characterized by low biodegradability, high toxicity and the high ability to bioaccumulate in water. In addition, it was found that this substance is mutagenic and carcinogenic (Ocampo-Perez et al 2013;Magalhães et al 2014). Therefore, it is not surprising that many efforts are directed to remove the contamination of metronidazole from the aqueous environment.…”