28 research outputs found
Reduction of vanadate to vanadyl by a strain of Saccharomyces cerevisiae
No full textThree strains of Saccharomyces cerevisiae, SC-1, DBVPG 6173 and DBVPG 6037, were studied for vanadate resistance in complex Sabouraud medium since they did not thrive in different minimal media (yeast nitrogen base with and without amino acids). The strain SC-1 was resistant up to 16 mM of vanadate, whereas the strains DBVPG 6173 and DBVPG 6037 were inhibited by 8 mM and 4 mM vanadate, respectively. The vanadate resistance in strain SC-1 was constitutive and due to the reduction of this oxyanion to vanadyl, which was detected by EPR spectroscopy and visible spectroscopy. The transformation of vanadate to vanadyl took place during the exponential growth phase; 10 mM of vanadate was reduced to vanadyl outside the cells since the oxyanion was not detected in the cell biomass and only a negligible concentration of vanadyl (25 nmoles mg(-1) cells dry weight) was found in the biomass. The other two vanadate-sensitive yeast strains only accumulated vanadate and did not reduce the oxyanion to vanadyl
Naphthalene and byphenyl oxidation by two Pseudomonas strains isolated from Venice lagoon sediment.
No full textA sediment sample from Venice Lagoon was found to be contaminated with 475 mgKg1 polycyclic aromatic hydrocarbons (PAHs). Naphthalene was the principal pollutant at 26% of total PAHs. Two strains of Pseudomonas SN1 and SB1 were isolated from sediment amended with 2% naphthalene. 16S rRNA gene sequence analysis indicated that the two strains have about 99% nucleotide identity with strains of the genus Pseudomonas, and are very close to Pseudomonas stutzeri. Their metabolic profiles showed significant nutritional differences, the most significant of which was that SN1 grows in marine mineral medium spiked with naphthalene and SB1 grows with biphenyl as sole carbon and energy sources. Pseudomonas sp. SN1 had a doubling time of 3.1 h with 2% naphthalene and SB1 had a doubling time of 19.5 h with 2% biphenyl. Strain SN1 oxidised naphthalene at 564732 mgO2 l1 d1 and SB1 oxidised biphenyl at 426725 mgO2 l1 d1 in respirometry reaction vessels under controlled conditions. Screening of the two strains for dioxygenase genes involved in the first step of the two hydrocarbon degradation pathways, by polymerase chain reaction, showed naphthalene dioxygenase in SN1 and biphenyl dioxygenase in SB1. The strains each have a different catechol 2,3-dioxygenase responsible for cleavage of the aromatic ring
Production of methyl mercury by sulphate-reducing bacteria in sediments from the Orbetello lagoon in presence of high macroalgal loads
No full textMethylmercury is a potent neurotoxin affecting shallow-water ecosystems. Mercury polluted sediment samples were collected at six different sites in the Orbetello Lagoon (central Italy) characterized by high levels of silt, iron, manganese hydroxides, and organic matter originated the latter originated from the decomposition of macroalgae. Porous water pointed out the presence of sulphates, methylmercury, and sulphides. Slurries arranged in anaerobic conditions from sediment aliquots from the six sites, with the addition of ionic mercury, highlighted the production of methylmercury. Sulphate reducing bacteria (SRB) were quantified in lagoon sediments; furthermore, sediments cultured under anaerobic conditions showed SRBs active in mercury methylation. Anaerobic cultures of SRB, amended with ionic mercury, produced methylmercury during the growth of bacterial cells. The percentage of aerobic mercury resistant bacteria was pointed out at each sampling site, evidencing the presence of bioavailable mercury. Several aerobic mercury resistant bacteria were isolated and their level of resistance to inorganic and organic forms of mercury was evaluated. These isolates may be potentially used for eventual bioremediation processes. Mercury methylation by SRB in the Orbetello Lagoon sediments was described for the first time, focusing the attention on the need for possible bioremediation processes by using autochthonous mercury resistant bacteria. Moreover, the influence of algal biomass on mercury methylation was highlighted for the first time in this lagoon ecosystem. The importance of removing algal biomass, as it represents a source of organic matter favouring the process of mercury methylation, was strongly pointed out in this stud
Envelope glycosilation determined in microscopy sections by lectines in Acinetobacter venetianus induced by diesel fuel.
No full textArsenic-resistant Pseudomonas spp. and Bacillus sp. bacterial strains reducing As(V) to As(III), isolated from Alps soils, Italy
No full textFive arsenic-resistant bacterial strains (designated
MP1400, MP1400a, MP1400d, APSLA3, and BPSLA3)
were isolated from soils collected at the Alps region (Italy),
which showed no contamination by arsenic. Phylogenetic
analysis of the 16S rRNA gene sequences assigned them to the
genera Pseudomonas and Bacillus. Bacillus sp. strain 1400d
and Pseudomonas spp. strains APSLA3 and MP1400 showed
higher tolerance to As(III), as indicated by minimum inhibitory
concentrations of 10 mmol/L. Pseudomonas sp. strain MP1400
exhibited higher tolerance to As(V) (minimum inhibitory
concentration of 135 mmol/L). The isolated arsenic-resistant
strains were able to reduce As(V) to As(III), especially
Pseudomonas sp. strain MP1400 reducing 2 mmol/L of As
(V) to As(III) within 24 h. The results suggest that the
isolated bacterial strains play a role in the arsenic biogeochemical
cycle of arsenic-poor soils in the Alps mount area
Environmental quality assessment of the marine reserves of the Tuscan Archipelago, Central Tyrrhenian Sea (Italy)
No full textThere has been a worldwide increase in the number of Marine Protected Areas and marine reserves over the last decade. In these areas, the protection measures adopted are related to specific management goals; nevertheless, actual knowledge of the effectiveness of the restrictions is far from exhaustive. This article aims to contribute to knowledge of the environmental quality of the marine reserves in the Tuscan Archipelago (Mediterranean central area) which is composed of seven islands at different levels of protection. A monitoring programme spanning multiple years was performed on water and sediment samples to finalise a definition of the trophic levels and the response of microbiological indicators (total heterotrophic bacteria, Actynomyces, hydrocarbon-degrading bacteria) to persistent organic pollutants (polychlorinated biphenyls, 1,1-bis-(4-chlorophenyl)-2,2-dichloroethene, hexachlorobenzene and polybrominated diphenyl ethers) was assessed. The results showed that these reserves were generally of good quality. A clear fingerprint produced by human activities along the coast and significant differences relating to the level of protection were observed. There exists the need to also consider basin dynamics when planning the protection management strategies adopted for marine reserves
Sea Level Rise Impacts in Coastal Areas and Possible Mitigation Engineering Approaches
No full textCoastal areas are subjected to both natural and man-made actions, leading to a deterioration of coastal structures. Climate change has had a heavy impact on these areas in recent years. An important consequence of these actions is sea level rise. This phenomenon is the most important cause of coastal erosion, a serious problem with ecological, economic, and human health consequences. The countermeasures to contrast this phenomenon and the degradation of the entire coastal system, are represented by engineering interventions. These basically consist of approaches for adaptation to sea level rise, namely protection, retreat, and accommodation. Variations and site adaptation of these actions can involve procedures of no intervention; advancement; protection; retreat; accommodation; and ecosystem-based adaptation. While these procedures have provided coastal benefits and protection, in the long run, they may cause further coastal disruption and further aggravate the situation. Such interventions, therefore, require an accurate assessment of the advantages and disadvantages. However, it is certainly necessary to proceed with actions aimed at mitigating climate change, respecting the rules in a sustainable way
Antibiotic-Resistant Bacteria in Aquaculture and Climate Change: A Challenge for Health in the Mediterranean Area
No full textAquaculture is the productive activity that will play a crucial role in the challenges of the millennium, such as the need for proteins that support humans and the respect for the environment. Aquaculture is an important economic activity in the Mediterranean basin. A great impact is presented, however, by aquaculture practices as they involve the use of antibiotics for treatment and prophylaxis. As a consequence of the use of antibiotics in aquaculture, antibiotic resistance is induced in the surrounding bacteria in the column water, sediment, and fish-associated bacterial strains. Through horizontal gene transfer, bacteria can diffuse antibiotic-resistance genes and mobile resistance genes further spreading genetic determinants. Once triggered, antibiotic resistance easily spreads among aquatic microbial communities and, from there, can reach human pathogenic bacteria, making vain the use of antibiotics for human health. Climate change claims a significant role in this context, as rising temperatures can affect cell physiology in bacteria in the same way as antibiotics, causing antibiotic resistance to begin with. The Mediterranean Sea represents a ‘hot spot’ in terms of climate change and aspects of antibiotic resistance in aquaculture in this area can be significantly amplified, thus increasing threats to human health. Practices must be adopted to counteract negative impacts on human health, with a reduction in the use of antibiotics as a pivotal point. In the meantime, it is necessary to act against climate change by reducing anthropogenic impacts, for example by reducing CO2 emissions into the atmosphere. The One Health type approach, which involves the intervention of different skills, such as veterinary, ecology, and medicine in compliance with the principles of sustainability, is necessary and strongly recommended to face these important challenges for human and animal health, and for environmental safety in the Mediterranean area
Growth of rhodosporidium toruloides strain DBVPG 6662 on dibenzothiophene crystals and orimulsion
No full textMicrobial Reduction of Hexavalent Chromium as a Mechanism of Detoxification and Possible Bioremediation Applications
No full text
