have been found in the rhizosphere region of soil implying the relevance of this bacterium as a nitrogen fixer. this bacterium has been isolated from oil-contaminated soil and marine water/sediment samples. while most pseudomonas strains that have been isolated from marine environments are eventually transferred to another genus after classification, p. stutzeri is one of the few strains that has not. this strain meets the requirements of being able to tolerate nacl and it is found in water columns in the pacific ocean and sediments in the mediterranean. these marine strains have many ecological roles including naphthalene degradation, sulfur oxidation, and most importantly denitrification and diazotrophy (nitrogen fixation). there is also evidence of p. stutzeri in wastewater treatment plants. zobell, an10, nf13, mt-1, and hta208 are the most significant strains isolated from marine environments and have been found in places such as water columns in the pacific-ocean, polluted mediterranean marine sediments, galapagos rifts near hydrothermal vent at depths of 2500 meters, and mariana trench samples at 11 000 meters. several other p. stutzeri strains have even been found in other locations such as manure, pond water, straw and humus samples. relevance health several strains of pseudomonas stutzeri have been found to behave as opportunistic pathogens in humans. it was not until 1973, however, that p. stutzeri's ability to cause infection started to become a topic of discussion within scientific literature. the first known infection was observed in combination with a permanent tibial fracture that required surgery. since that initial infection, p. stutzeri has been able to cause infections within individuals that have a variety of illnesses, including: endocarditis, infections of the bone, eye, skin or urinary tract, meningitis, pneumonia, arthritis, and several others. some patients even have health conditions as serious as tumors, infected joint cavities and collapsed lungs. within those infected, p. stutzeri strains have been isolated from the blood, feces, cerebral spinal fluid, ears, eyes, and organ systems (such as respiratory and urinary). when strains of this bacterium are discovered within infected patients they are often accompanied by other pathogenic microbes. while p. stutzeri has caused numerous infections since it has been discovered, it has caused few deaths, giving it a much lower virulence rating in relation to other pseudomonas species, such as pseudomonas aeruginosa. despite its lack of major virulence, however, this bacterium still poses a threat to human health because it contains a variety of antibiotic resistance mechanisms. in fact, p. stutzeri has so many resistance mechanisms that antibiotic-resistant p. stutzeri strains have been discovered and isolated for almost every antibiotic family except fluoroquinolones. some of the more-studied resistance mechanisms include: utilization of beta-lactamases, which are able to cleave penicillins, cephalosporins, and other antibiotic classes, and ability to vary lipopolysaccharide and outer membrane protein components. in order to gain resistance to fluoroquinolones, mutations in the gyra (gyrase gene) and parc(topoisomerase iv gene) are often needed, mutations which are not as common. only one strain of p. stutzeri, strain 13, has been found to have mutations that allow it to be resistant to fluoroquinolones. the reason p. stutzeri strains are less of a concern for major antibiotic resistance as compared to other pseudomonas strains, like p. aeruginosa, is likely due to the fact the strains are less common in clinical settings and thus less frequently exposed to antibiotics. environmental some strains of p. stutzeri are capable of associating with pollutants and toxic metals, such as biocides and oil derivatives, in such a way that allows the bacterium to promote the degradation of these substances. other strains of this bacterium have metabolic capabilities, such as metal cycling, that allow for the preservation of essential metals, such as copper and iron, and the degradation of toxic metals, such as uranium and lead. one specific strain of p. stutzeri, strain rch2, is currently being studied as a potential tool for the bioremediation of soil and water supplies since it has shown an ability to reduce hexavalent chromium concentrations in areas where this pollutant is high. several other p. stutzeri strains, such as strain a15, have demonstrated an ability to reduce atmospheric nitrogen so they are being explored as agents to help increase plant growth. these strains are specifically being studied for use in rice plants because they have been shown to naturally infect and inhabit the roots of these plants. by living within the roots, p. stutzeri is able to supply the plants directly with the reduced nitrogen compounds they produce. microbiological several different strains of p. stutzeri have been found to be competent for natural genetic transformation. the frequency of transformation between individuals of the same p. stutzeri strain is typically high. between individuals of different strains, or between p. stutzeri strains and other pseudomonas species, however, the frequency of transformation is usually greatly reduced. the complete genome sequence of a highly transformable p. stutzeri strain, strain 28a24, has been determined and is available for observation.