Persistence and dispersion of Acinetobacter spp. in the urban water cycle

Dissertação de mestrado em Genética MolecularAs bactérias do género Acinetobacter são ubíquas no solo, esgotos e água. Tendo como objectivo avaliar a persistência e possíveis rotas de dispersão das Acinetobacter spp. no ciclo urbano da água, uma colecção de 254 isolados foram recuperados da água de uma estação de tratamento de águas (ETA) e de 12 torneiras. Numa triagem inicial, os isolados foram identificados preliminarmente usando primers específicos para 16S ARNr de Acinetobacter spp., levando à selecção de 179 isolados. Depois desta triagem, foi usado um esquema de mini-Multilocus Sequencing Typing (MLST) de maneira a conseguir a identificação ao nível da espécie, e quando possível, avaliar padrões de variação intra-específica. Foi determinada a resistência aos antibióticos amoxicilina, ticarcilina, cefalotina, ceftazidime, meropenemo, gentamicina, ciprofloxacina, sulfametoxazol, sulfametoxazol/trimetoprim, tetraciclina, sulfato de colistina e estreptomicina, pelo método de difusão de disco. Os padrões do mini-MLST e os perfis de resistência a antibióticos foram analisados como função do local de isolamento. Visto que não foram observados tipos de sequências (ST) idênticos nos dois ambientes amostrados, concluiu-se que Acinetobacter spp. isolados de torneiras não tinham origem na ETA. Não obstante, foi possível inferir a existência de uma fonte comum de Acinetobacter spp. nas torneiras, visto ter sido observado o mesmo ST em diferentes torneiras, assim como em distintos sistemas de distribuição de água. A respeito da persistência de Acinetobacter spp. nos diferentes locais de amostragem, os isolados com sequências de rpoB ou recA idênticas, que foram observadas nos diferentes períodos, foram distinguidos pelo fenótipo de resistência a antibióticos. Além disso, os dados obtidos sugerem que a densidade de Acinetobacter spp. no ciclo urbano da água pode aumentar durante o período de Verão, diminuindo durante o Inverno, podendo haver uma nova colonização no ano seguinte. Sete isolados pertencentes ao mesmo grupo de ST, apresentavam distintos perfis de resistência a antibióticos, sugerindo que, ou essas resistências foram adquiridas após a colonização do sistemas de águas, ou o método de tipagem tem baixa resolução. Neste aspecto, admite-se que a análise de sequências nucleotídicas de outros genes contribuirá para uma melhor diferenciação de estirpes e portanto, permitirá ultrapassar a referida limitação.Members of the genus Acinetobacter are ubiquitous in soil, sewage and water. Aiming the assessment of the persistence and possible routes of dispersion of Acinetobacter spp. in the urban water cycle, a collection of 254 bacterial isolates were recovered from two different types of water, from a water treatment plant (WTP) and from 12 taps. In the initial screening, isolates were presumptively identified using an Acinetobacter spp. specific 16S rRNA primer, leading to the selection of a set of 179 isolates. After this screening, a mini-MLST approach was used in order to achieve the identification to the species level and, whenever possible, to assess patterns of intra-specific variation. The antibiotic resistance to amoxicillin, ticarcillin, cephalothin, ceftazidime, meropenem gentamicin, ciprofloxacin, sulphamethoxazole, sulphamethoxazole/trimethoprim, tetracycline, colistin-sulphate, and streptomycin was determined using the diffusion disc method. The mini-MLST patterns and the antibiotic resistance profile were analyzed as a function of the isolation site. Given that no identical sequencing type (ST) was observed in both types of sampling site, it was concluded that Acinetobacter spp. isolated from the taps did not have origin in the WTP. Nevertheless, a common source of tap water Acinetobacter spp. was hinted by the observation of the same ST in different taps and water distribution systems (WDS). In respect to Acinetobacter spp. persistence in the different sampling sites, the isolates with identical rpoB or recA nucleotide sequences in the different sampling periods, were distinguished by antibiotics resistance patterns. Moreover, it was suggested that the presence of Acinetobacter spp. in the urban water cycle rises during the summer period and vanishes during winter, with a new colonization in the following year. Seven isolates belonging to the same ST group, could be distinguished on basis of the antibiogram phenotype, suggesting either that those resistance phenotypes were acquired after the water system colonization, or that the typing method had a the poor resolution . The use of additional gene sequences for strain differentiation will contribute to overcome this limitation

blaTEM and vanA as indicator genes of antibiotic resistance contamination in a hospital–urban wastewater treatment plant system

Four indicator genes were monitored by quantitative PCR in hospital effluent (HE) and in the raw and treated wastewater of the municipal wastewater treatment plant receiving the hospital discharge. The indicator genes were the class 1 integrase gene intI1, to assess the capacity of bacteria to be involved in horizontal gene transfer processes; blaTEM, one of the most widespread antibiotic resistance genes in the environment, associated with Enterobacteriaceae; vanA, an antibiotic resistance gene uncommon in the environment and frequent in clinical isolates; and marA, part of a locus related to the stress response in Enterobacteriaceae. Variation in the abundance of these genes was analysed as a function of the type of water, and possible correlations with cultivable bacteria, antimicrobial residue concentrations, and bacterial community composition and structure were analysed. HE was confirmed as an important source of blaTEM and vanA genes, and wastewater treatment showed a limited capacity to remove these resistance genes. The genes blaTEM and vanA presented the strongest correlations with culturable bacteria, antimicrobial residues and some bacterial populations, representing interesting candidates as indicator genes to monitor resistance in environmental samples. The intI1 gene was the most abundant in all samples, demonstrating that wastewater bacterial populations hold a high potential for gene acquisitioninfo:eu-repo/semantics/acceptedVersio

Bacterial community and antibiotic resistance dynamics in a full-scale wastewater treatment plant with UV disinfection

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Diversity and antibiotic resistance of Acinetobacter spp. in water from the source to the tap

Acinetobacterspp. are ubiquitous bacteria in the environment.Acinetobacterspp. isolated from a municipal drinking water treatment plant and from connected tap waterwere identified to the species level on the basis ofrpoB genepartial sequence analysis. Intraspecies variation wasassessed based on the analysis of partial sequences of house-keeping genes (rpoB,gyrB, andrecA). Antibiotic resistancewas characterized using the disk diffusion method and iso-lates were classified as wild or non-wild type (non-WT),according to the observed phenotype. The strains ofAcinetobacterspp. were related to 11 different validly pub-lished species, although three groups of isolates, presentinglowrpoB sequence similarities with previously describedspecies, may represent new species. Most of the isolateswere related to the speciesA. johnsoniiandA. lwoffii.These two groups, as well as others related to the speciesA. parvusandA. tjernbergiae, were detected in the watertreatment plant and in tap water. Other strains, related to thespeciesA. pittiiandA. beijerinckii, were isolated only fromtap water. Most of the isolates (80 %) demonstrated wild type (WT) to all of the 12 antibiotics tested. Non-WT fortetracycline, meropenem, and ceftazidime, among others,were observed in water treatment plant or in tap watersamples. Although, in general, this study suggests a lowprevalence of acquired antibiotic resistance in waterAcinetobacterspp., the potential of some species to acquireand disseminate resistance via drinking water is suggested.info:eu-repo/semantics/publishedVersio

Bacterial lineages putatively associated with the dissemination of antibiotic resistance genes in a full-scale urban wastewater treatment plant

Urban wastewater treatment plants (UWTPs) are reservoirs of antibiotic resistance. Wastewater treatment changes the bacterial community and inevitably impacts the fate of antibiotic resistant bacteria and antibiotic resistance genes (ARGs). Some bacterial groups are major carriers of ARGs and hence, their elimination during wastewater treatment may contribute to increasing resistance removal efficiency. This study, conducted at a full-scale UWTP, evaluated variations in the bacterial community and ARGs loads and explored possible associations among them. With that aim, the bacterial community composition (16S rRNA gene Illumina sequencing) and ARGs abundance (real-time PCR) were characterized in samples of raw wastewater (RWW), secondary effluent (sTWW), after UV disinfection (tTWW), and after a period of 3 days storage to monitoring possible bacterial regrowth (tTWW-RE). Culturable enterobacteria were also enumerated. Secondary treatment was associated with the most dramatic bacterial community variations and coincided with reductions of ~2 log-units in the ARGs abundance. In contrast, no significant changes in the bacterial community composition and ARGs abundance were observed after UV disinfection of sTWW. Nevertheless, after UV treatment, viability losses were indicated ~2 log-units reductions of culturable enterobacteria. The analysed ARGs (qnrS, blaCTX-M, blaOXA-A, blaTEM, blaSHV, sul1, sul2, and intI1) were strongly correlated with taxa more abundant in RWW than in the other types of water, and which associated with humans and animals, such as members of the families Campylobacteraceae, Comamonadaceae, Aeromonadaceae, Moraxellaceae and Bacteroidaceae. Further knowledge of the dynamics of the bacterial community during wastewater treatment and its relationship with ARGs variations may contribute with information useful for wastewater treatment optimization, aiming at a more effective resistance control.info:eu-repo/semantics/acceptedVersio

Valorization of Wastes for Biodiesel Production: The Brazilian Case

This chapter intends to bring an overview about the Brazilian researches and their contributions to the production of biodiesel from wastes. Currently, the main obstacles to spread the use of biodiesel are its high cost of production and the competition between biodiesel and food industries. So, the use of wastes plays an important role in reducing the biodiesel costs and reusing the materials that have no other applications, as deodorization residues, neutralization soap sticks, and animal fats, among others. Then, we present a review about Brazilian studies involving waste oils and fatty–acid-rich raw materials that helped the advancement in this field of knowledge during the last few years

Microbiological quality of treated water by solar-driven oxidation processes

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Diversity and antibiotic resistance of Acinetobacter spp. in water from the source to the tap

Abstract Acinetobacter spp. are ubiquitous bacteria in the environment. Acinetobacter spp. isolated from a municipal drinking water treatment plant and from connected tap water were identified to the species level on the basis of rpoB gene partial sequence analysis. Intraspecies variation was assessed based on the analysis of partial sequences of housekeeping genes (rpoB, gyrB, and recA). Antibiotic resistance was characterized using the disk diffusion method and isolates were classified as wild or non-wild type (non-WT), according to the observed phenotype. The strains of Acinetobacter spp. were related to 11 different validly published species, although three groups of isolates, presenting low rpoB sequence similarities with previously described species, may represent new species. Most of the isolates were related to the species A. johnsonii and A. lwoffii. These two groups, as well as others related to the species A. parvus and A. tjernbergiae, were detected in the water treatment plant and in tap water. Other strains, related to the species A. pittii and A. beijerinckii, were isolated only from tap water. Most of the isolates (80 %) demonstrated wild type (WT) to all of the 12 antibiotics tested. Non-WT for tetracycline, meropenem, and ceftazidime, among others, were observed in water treatment plant or in tap water samples. Although, in general, this study suggests a low prevalence of acquired antibiotic resistance in water Acinetobacter spp., the potential of some species to acquire and disseminate resistance via drinking water is suggested

Zeolites: A Theoretical and Practical Approach with Uses in (Bio)Chemical Processes

This review provides a state-of-the-art summary of distributed zeolite technology, as well as identifying strategies to further promote the absorption of these materials in various areas of study. Zeolites are materials that can be synthesized or found in natural rock deposits a with a basic composition consisting in Al, Si, and O. Zeolite’s consideration as a future material is due to many facile synthesis methods to obtain different structures with variations in pore size, surface area, pore volume and physical properties. These methods are developed using the control of relevant synthesis parameters that influences structure formation, such as crystallization temperature, time of aging and/or crystallization, stoichiometric relationships between components of synthesis gel, pH of the medium, and in some cases the type of structure-directing agent. Each method will lead to geometric changes in the framework formation, making possible the formation of typical chemical bonds that are the fingerprint of any zeolitic structure (O-Si-O and Al-O-Si), forming typical acid sites that give specificity in zeolite and allows it to act as a nanoreactor. The specificity is a characteristic that in some cases depends on selectivity, a fundamental property derived of the porosity, mostly in processes that occur inside the zeolite. In processes outside the structure, the surface area is the main factor influencing this property. Moreover, there are many natural sources with adequate chemical composition to be used as precursors. Some of these sources are waste, minimizing the deposition of potential hazardous materials that can be recalcitrant pollutants depending on the environment. Besides its uses as a catalyst, zeolite serves as a support for many bioprocesses; therefore, this review aims to explain relevant aspects in chemical nature, physical properties, main methods of synthesis, main precursors used for synthesis, and relevant applications of zeolites in chemical catalysis and biological processes

The influence of the autochthonous wastewater microbiota and gene host on the fate of invasive antibiotic resistance genes

The aim of this study was to assess the fate of invasive antibiotic resistance genes (ARG) discharged in wastewater. With this objective, antibiotic resistant bacteria (ARB) known to harbor specific ARG were inoculated in wastewater (hospital effluent, or municipal raw and treated wastewater) and in ultra-pure sterile water microcosms. Two sets of wastewater ARB isolates were used - set 1, Enterococcus faecalis, Acinetobacter johnsonii, Klebsiella pneumoniae and set 2, Enterococcus faecium, Acinetobacter johnsonii, Escherichia coli. Non-inoculated controls were run in parallel. Samples were collected at the beginning and at the end (15 days) of the incubation period and the abundance of the genes 16S rRNA, intI1, blaTEM and vanA and the bacterial community composition were analyzed. In general, the genes blaTEM and vanA had lower persistence in wastewater and in ultra-pure water than the genes 16S rRNA or the class 1 integron integrase intI1. This effect was more pronounced in wastewater than in ultra-pure water, evidencing the importance of the autochthonous microbiota on the elimination of invasive ARG. Wastewater autochthonous bacterial groups most correlated with variations of the genes intI1, blaTEM and vanA were members of the classes Gammaproteobacteria, Bacilli or Bacteroidia. For blaTEM, but not for vanA, the species of the ARB host was important to determine its fate. These are novel findings on the ecology of ARB in wastewater environments.info:eu-repo/semantics/publishedVersio