The genus Gluconobacter is industrially important due to the ability to accomplish unusual and almost complete oxidation reactions (bioconversions) and to contaminate high sugar content products. Following preliminary evidence that some strains of Gluconobacter were resistant to cadmium, and realizing that cadmium resistance among gram-negative organisms is often encoded by an operon which also encodes cobalt and zinc resistance via an efflux mechanism, 10 strains of Gluconobacter were tested for heavy-metal resistance. Three of the 10 representative strains appeared to be resistant to cadmium chloride, and two were also resistant to cobalt- and zinc chloride. These strains, as well as two cadmium-sensitive strains were analyzed using PCR and sequencing to establish gene homology with Ralstonia eutropha, the most frequently studied Gram-negative bacterium exhibiting cadmium resistance. Amplification of two genes from the czc operon, known to encode cadmium, cobalt and zinc resistance in Ralstonia, was attempted in the three resistant and two sensitive strains of Gluconobacter. The gene, czcA, thought to encode the main pump protein of the efflux mechanism, was found in all Gluconobacter strains tested. However, amplification of a regulatory gene czcD, thought to sense the extracellular metal ion concentration, was not possible in the Gluconobacter strains tested. The PCR products were sequenced and analyzed for homology to the czc operon in Ralstonia. From the data gathered, it appears as though some strains of Gluconobacter contain at least a portion of the czc operon , encoding cadmium, cobalt and zinc resistance in Ralstonia eutropha. / Master of Science

Made available in DSpace on 2014-12-17T14:20:09Z (GMT). No. of bitstreams: 1 JessicaSM_DISSERT.pdf: 4464945 bytes, checksum: 1436f4eaf0ddca5a64460da0b3822df7 (MD5) Previous issue date: 2013-03-15 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Our research intends to comprehend the configuration of the resistance (Foucault) as the stylization of life in the contemporary world, taking Heavy Metal as the specific object of study. We believe that Heavy Metal is an ethopoietical device which admits practices of freedom withstanding the reified moral habits since the beginning of the socialization. This is reflected, mainly, in the creation of new individual and communal ways to stylize the life. We also suggest an expansion of Foucault s concept of resistance, considering the idea of consumer society described by Zygmunt Bauman. Our hypothesis understands that the contact with the underground of Heavy Metal provides new ethical manners (Foucault), where the individual take the Heavy Metal as a way of life. At this point, the consumption becomes a key-word since the participation in the underground of Heavy Metal is a way of consumption out of the rules of marketing a practice of freedom, a way of particular existence , being different in both mode and duration / Nossa pesquisa visa compreender a configura??o da resist?ncia (Foucault) enquanto estiliza??o da vida na contemporaneidade, tendo o Heavy Metal enquanto objeto de estudo espec?fico. Acreditamos que o Metal se configure em um dispositivo ethopoi?tico possibilitador de pr?ticas de liberdade frente aos h?bitos morais reificados desde os prim?rdios da socializa??o do sujeito. Isso se reflete, principalmente, na cria??o de novas maneiras de estilizar a vida que s?o individuais e grupais, ao mesmo tempo. Sugerimos tamb?m uma amplia??o do pensamento sobre o tema da resist?ncia, em Foucault, tendo em vista a sociedade de consumo descrita por Zygmunt Bauman. Nossa hip?tese ? a de que o contato com o mundo underground do Heavy Metal ? o possibilitador de novas formas ?ticas (Foucault), onde h? a ades?o e o comprometimento do sujeito com o Heavy Metal enquanto um modo de vida. A partir da?, o consumo se torna uma palavra chave, na medida em que, participar do underground do Heavy Metal - enquanto uma pr?tica de liberdade, um modo de exist?ncia particular constitui tamb?m uma forma de consumo que foge ?s regras gerais do mercado, sendo um consumo diferenciado tanto na forma quanto na sua dura??o

Master of Science / Department of Diagnostic Medicine/Pathobiology / Tiruvoor G. Nagaraja / Sanjeevkumar Narayanan / Antimicrobials are included in finishing cattle diets for growth promotion, feed efficiency, and protection against liver abscesses. The inclusion of in-feed antimicrobials at or below therapeutic concentrations may provide a selective pressure for antimicrobial resistant microorganisms. Additionally, heavy metals such as copper and zinc may be included in cattle diets because of growth-promoting effects. Heavy metal resistance genes are on transferable plasmids that also contain antimicrobial resistance genes. The objectives of this research were to 1) determine the prevalence of food-borne pathogens, Salmonella and E. coli O157, in cattle fed diets with or without monensin and tylosin and 0 or 25% wet corn distiller's grains (WDGS), 2) determine the prevalence of food-borne pathogens in cattle fed elevated concentrations of copper and zinc 3) evaluate the effect of antimicrobials on antimicrobial susceptibility of food-borne pathogens and commensal fecal bacteria, and 4) determine a possible association between in-feed antimicrobials and the concentration of antimicrobial resistance genes in the feces of cattle. Inclusion of 25% WDGS was associated with a higher prevalence of E. coli O157 on one of two sample collection days; however, there was no association between the use of monensin and tylosin, or copper and zinc on the prevalence of food-borne pathogens. Including monensin and tylosin in cattle diets was associated with an increased resistance of enterococci to macrolides, but was not related to concentration of the common macrolide resistance gene, ermB. In cattle fed diets with copper and/or zinc, no differences were observed in antimicrobial susceptibility or the concentration of antimicrobial resistance genes. In conclusion, results indicate that including growth-promoting antimicrobials in cattle diets at below therapeutic concentrations only limitedly impacted antimicrobial susceptibility and concentration of fecal antimicrobial resistance genes; however, this research encompassed only a select number of microorganisms. The positive association between WDGS and E. coli O157 prevalence in cattle has important implications for food safety, and warrants further investigation.

The rising number of antibiotic resistant bacteria (ARB) may introduce to the post antibiotic era because they cause a loss of the therapeutic potential of antibiotics. For many years the important role of the natural environment as reservoir and dissemination pathway for ARB and responsible genes has been largely overlooked. However, especially aquatic ecosystems provide optimal conditions for the antibiotic resistance (AR) evolution: first, aquatic ecosystems are frequently affected by anthropogenic activities that cause multiple pollutions for example with heavy metals, that potentially cause co-selection of antibiotic- and heavy metal resistance. Second, aquatic ecosystems feature a dissemination pathway between human populations and natural environments via the urban water cycle. Water cycles between human associated environments (e.g. house holds and clinics) via waste water through waste water treatment plants into natural ecosystems (e.g. water bodies) and back as drinking water after purification. Third, ecosystem internal biotic interactions such as competition between bacteria and predation by the natural consumers seem to impact AR evolution sustainably. The present doctoral thesis focuses on the impact of abiotic and biotic factors on the proliferation of AR and responsible genes in natural aquatic environments, with special emphasis on (i) heavy metal driven co-selection of antibiotic and heavy metal resistance and (ii) on the impact of competition and predation on the evolution of AR. In order to quantify the risk of heavy metal driven co-selection for AR spread, I provide a first risk assessment based on literature values of environmental heavy metal loadings and related AR. Additionally, I developed a limit value named minimum co-selective concentration (MCC), which is the lowest concentration of a heavy metal that can potentially cause coselection in nature. It turned out that Cu, Zn, Ni, Hg, and Cd are suspected to be the main co-selecting heavy metals in the aquatic environment. I further investigated heavy metal driven co-selection of AR in a river ecosystem, the Western Bug River (Ukraine). I found indications for co-selection of resistance to five antibiotics (ciprofloxacin, gentamicin, amikacin, tobramycin, and cefepime) and two metals (Ni and Cd) caused by Ni- and Cd-levels. Both metals exceed their MCC for water samples and Cd additionally in sediments. As a second focal point the present work emphasis on ecological interactions effecting AR evolution. Currently three possible effects of ecological interactions on AR spread are discussed. First, environmental antibiotic levels are rather low, however they might favour ARB due to a competitive advantage. The reason is that even sublethal antibiotic levels reduce the growth of sensitive bacteria while resistant cells remain unaffected by the antibiotic action. Second, predation by protozoa is believed to impact conjugation between prey bacteria (and thus the transfer of DNA and potential resistance genes) by keeping bacteria in a growing stage that favours conjugation. Third, in order to escape predation by protozoa, bacteria evolved grazing defence mechanisms such as the formation of inedible biofilms, which can feedback on the evolution of AR. With an ordinary differential equation model, I tested the effect of low antibiotic levels and losses (e.g. due to predation) on the proliferation of ARB in a modelled planktonic system. In case that the model contains the mechanism that conjugation frequencies are highest during exponential growth, I found that (i) (grazing) losses enhance conjugation frequencies between bacteria and that (ii) medium levels of antibiotics and (grazing) losses favour resistant cells in the competition to sensitive bacteria. Biofilms are thought to be \'hot spots\' for conjugation but some plasmids have lower conjugation frequencies in biofilms compared to planktonic systems. As a first step, in order to discover predation effects on plasmid spread in plankton - biofilm systems I investigated grazing resistance of bacteria in grazing experiments. Both plankton and biofilm phenotypes were consumed, when exposed to their specialized grazer (either plankton-feeder or biofilmfeeder), whereas the other phenotype remained grazing-resistant and thus became the dominant prey type. Both predators together effectively control planktonic and biofilm prey. With regards to the spread of AR-genes via conjugation, I speculate that the feeding preference of the present predator can affect the invasion success of resistance plasmids in planktonic - biofilm systems. For dynamic systems, I assume that dynamics of predator and prey traits (plankton vs. biofilm-feeder and biofilm vs. planktonic prey) will lead to dynamics of conjugation frequencies in planktonic or biofilm bacteria. I assume that conjugation events are more frequent in the dominant prey type (plankton or biofilm). However, other factors such as pili-type of the plasmid (short and rigid pili, prefers conjugation in biofilms or long and flexible pili, prefers conjugation in plankton) might additionally influence plasmid invasion success in plankton - biofilm morphotypes.

No description available.

No description available.

Anthropogenic activities generate waste products that pollute the environment with bacteria and heavy metals. This research assessed pollution of the Kahwa River, Bukavu Town, DRC with cadmium and lead (HMs) and bacterial enteropathogens. A survey of businesses, households and healthcare facilities showed general use of the river to remove effluent and waste. Indicator organisms were cultured at over 200 cfu/100 ml showing faecal contamination of the river water. Antibiotic resistance was shown by enteropathogenic Vibrio cholerae and Salmonella typhi to ampicillin and cotrimoxazole with some sensitivity shown to ciprofloxacin. River water contained HMs at around 40 times the World Health Organisation limit for drinking water. The bacteria, particularly from river sediment, tolerated HMs up to a concentration of 1.5 mg/ml. The presence in the Kahwa River of antibiotic-resistant pathogens showing tolerance to HMs has serious public health implications / Environmental Management / M.Sc. (Environmental management)

Anthropogenic activities generate waste products that pollute the environment with bacteria and heavy metals. This research assessed pollution of the Kahwa River, Bukavu Town, DRC with cadmium and lead (HMs) and bacterial enteropathogens. A survey of businesses, households and healthcare facilities showed general use of the river to remove effluent and waste. Indicator organisms were cultured at over 200 cfu/100 ml showing faecal contamination of the river water. Antibiotic resistance was shown by enteropathogenic Vibrio cholerae and Salmonella typhi to ampicillin and cotrimoxazole with some sensitivity shown to ciprofloxacin. River water contained HMs at around 40 times the World Health Organisation limit for drinking water. The bacteria, particularly from river sediment, tolerated HMs up to a concentration of 1.5 mg/ml. The presence in the Kahwa River of antibiotic-resistant pathogens showing tolerance to HMs has serious public health implications / Environmental Management / M.Sc. (Environmental management)

The goal of this project was to develop novel bacterial biomarkers for use in an industrial context. These biomarkers would be used to determine aluminium industry activity impact on a local ecosystem. Sediment bacterial communities of the Saguenay River are subjected to industrial effluent produced by industry in Jonquière, QC. In-situ responses of these communities to effluent exposure were measured and evaluated as potential biomarker candidates for exposure to past and present effluent discharge. Bacterial community structure and composition between control and affected sites were investigated. Differences observed between the communities were used as indicators of a response to industrial activity through exposure to effluent by-products. Diversity indices were not significantly different between sites with increased effluent exposure. However, differences were observed with the inclusion of algae and cyanobacteria. UniFrac analyses indicated that a control (NNB) and an affected site (Site 2) were more similar to one another with regard to community structure than either was to a medially affected site (Site 5) (Figure 2.4). We did not observe a signature of the microbial community structure that could be predicted with effluent exposure. Microbial community function in relation to bacterial mercury resistance (HgR) was also evaluated as a specific response to the mercury component present in sediments. Novel PCR primers and amplification conditions were developed to amplify merP, merT and merA genes belonging to the mer-operon which confers HgR (Table 5.6). To our knowledge, the roles of merP and merT have not been explored as possible tools to confirm the presence of the operon. HgR gene abundance in sediment microbial communities was significantly correlated (p < 0.05) to total mercury levels (Figure 3.4) but gene expression was not measurable. We could not solely attribute the release of Hg0 from sediments in bioreactor experiments to a biogenic origin. However, there was a 1000 fold difference in measured Hg0 release between control and affected sites suggesting that processes of natural remediation may be taking place at contaminated sites (Figure 3.7). Abundance measurements of HgR related genes represent a strong response target to the mercury immobilized in sediments. Biomarkers built on this response can be used by industry to measure long term effects of industrially derived mercury on local ecosystems. The abundance of mer-operon genes in affected sites indicates the presence of a thriving bacterial community harbouring HgR potential. These communities have the capacity to naturally remediate the sites they occupy. This remediation could be further investigated. Additional studies will be required to develop biomarkers that are more responsive to contemporary industrial activity such as those based on the integrative oxidative stress response.

The goal of this project was to develop novel bacterial biomarkers for use in an industrial context. These biomarkers would be used to determine aluminium industry activity impact on a local ecosystem. Sediment bacterial communities of the Saguenay River are subjected to industrial effluent produced by industry in Jonquière, QC. In-situ responses of these communities to effluent exposure were measured and evaluated as potential biomarker candidates for exposure to past and present effluent discharge. Bacterial community structure and composition between control and affected sites were investigated. Differences observed between the communities were used as indicators of a response to industrial activity through exposure to effluent by-products. Diversity indices were not significantly different between sites with increased effluent exposure. However, differences were observed with the inclusion of algae and cyanobacteria. UniFrac analyses indicated that a control (NNB) and an affected site (Site 2) were more similar to one another with regard to community structure than either was to a medially affected site (Site 5) (Figure 2.4). We did not observe a signature of the microbial community structure that could be predicted with effluent exposure. Microbial community function in relation to bacterial mercury resistance (HgR) was also evaluated as a specific response to the mercury component present in sediments. Novel PCR primers and amplification conditions were developed to amplify merP, merT and merA genes belonging to the mer-operon which confers HgR (Table 5.6). To our knowledge, the roles of merP and merT have not been explored as possible tools to confirm the presence of the operon. HgR gene abundance in sediment microbial communities was significantly correlated (p < 0.05) to total mercury levels (Figure 3.4) but gene expression was not measurable. We could not solely attribute the release of Hg0 from sediments in bioreactor experiments to a biogenic origin. However, there was a 1000 fold difference in measured Hg0 release between control and affected sites suggesting that processes of natural remediation may be taking place at contaminated sites (Figure 3.7). Abundance measurements of HgR related genes represent a strong response target to the mercury immobilized in sediments. Biomarkers built on this response can be used by industry to measure long term effects of industrially derived mercury on local ecosystems. The abundance of mer-operon genes in affected sites indicates the presence of a thriving bacterial community harbouring HgR potential. These communities have the capacity to naturally remediate the sites they occupy. This remediation could be further investigated. Additional studies will be required to develop biomarkers that are more responsive to contemporary industrial activity such as those based on the integrative oxidative stress response.