Mutual Impacts and Interactions of Antibiotic Resistance Genes, Microcystin Synthetase Genes, Graphene Oxide, and Microcystis Aeruginosa in Synthetic Wastewater

The physiological impacts and interactions of ARGs abundance, microcystin synthetase genes expression, GO, and M. aeruginosa in synthetic wastewater were investigated. The results demonstrated that the absolute abundance of sul1, sul2, tetW, and tetM in synthetic wastewater dramatically increased to 365.2%, 427.1%, 375.2%, and 231.7%, respectively, when the GO concentration was 0.01 mg/L. Even more interesting is that the sum gene copy numbers of mcyA-J also increased to 243.2%. The appearance of GO made the significant correlation exist between ARGs abundance and mcyA-J expression. Furthermore, M. aeruginosa displayed better photosynthetic performance and more MCs production at 0.01 mg/L GO. There were 65 pairs of positive correlations between the intracellular differential metabolites of M. aeruginosa and the abundance of sul1, sul2, tetM, and tetW with various GO concentrations. The GO will impact the metabolites and metabolic pathway in M. aeruginosa. The metabolic changes impacted the ARGs, microcystin synthetase genes, and physiological characters in algal cells. Furthermore, there were complex correlations among sul1, sul2, tetM, tetW, mcyA-J, MCs, photosynthetic performance parameters, and ROS. The different concentration of GO will aggravate the hazards of M. aeruginosa by promoting the expression of mcyA-J, producing more MCs, simultaneously, it may cause the spread of ARGs.

Molecular detection of hepatotoxic cyanobacteria in inland water bodies of the Marmara Region, Turkey

<p>Blooms of cyanobacteria are an increasingly frequent phenomenon in freshwater ecosystems worldwide as a result of eutrophication. Many species can produce hepatotoxins that cause severe health hazards to humans. The aim of this study was to identify the bloom forming cyanobacteria species by molecular methods and to amplify genes responsible for hepatotoxin biosynthesis from the environmental samples and isolated strains of cyanobacteria from Küçükçekmece Lagoon, Sapanca, İznik, Manyas and Taşkısı Lakes. A total of 10 bloom samples and 11 isolated strains were examined and <em>Microcystis</em> spp., <em>Planktothrix</em> spp., <em>Nodularia</em> <em>spumigena</em>, <em>Anabaenopsis</em> <em>elenkinii</em>, <em>Sphaerospermopsis</em> <em>aphanizomenoides</em>, <em>Cylindrospermopsis</em> <em>raciborskii</em> were identified. Hepatotoxin genes were detected in 60% of the bloom samples and 45% of the strains. Two Microcystis strains were obtained from Küçükçekmece Lagoon. While the strain assigned to <em>Microcystis</em> <em>flosaquae</em> was non-toxic, <em>Microcystis</em> <em>aeruginosa</em> strain produced microcystin. According to PCR results, the <em>M. aeruginosa</em> and <em>Planktothrix</em> <em>agardhii</em> bloom samples of Küçükçekmece Lagoon contained the microcystin synthetase gene E (mcyE) indicative of microcystin production, however, no microcystin was detected by HPLC. The mcyE gene was also found in <em>Microcystis</em> <em>wesenbergii</em> isolated from Taşkısı Lake, and in all <em>Planktothrix</em> <em>rubescens</em> bloom samples from Sapanca Lake. To our knowledge, this is the first detailed study for identifiying different toxic cyanobacteria species and their hepatotoxin production from several waterbodies in Turkey using molecular methods.</p>