Effects of growth temperature on the adhesion ofPseudomonas aeruginosa ATCC 27853 to polystyrene

The aim of this work has been to analyse the effects of temperature on polystyrene adhesion ofPseudomonas aeruginosa ATCC 27853. The bacterial adhesion (expressed as percentage of hydrophobicity) has been measured during the cultivation of this strain at different temperature of growth (15, 30 and 47°C). Data obtained showed that an increase in temperature is a factor that increasing the virulence of the strain in terms of adhesion to polystyrene surfaces. This kind of experiments surely brings important information concerning the prevention of nosocomial infection

Biodegradation of Aromatic Compounds

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous persistent environmental contaminants generated by natural combustion processes and human activities. PAHs are considered hazardous because of cytotoxic, mutagenic, and carcinogenic effects. Sixteen individual PAH compounds have been identified as priority pollutants by the United States Environmental Protection Agency (U.S. EPA). All substances originated in to the environment by either biogenic or anthropogenic sources. Anthropogenic compounds describe synthetic compounds, and compound classes as well as elements and naturally occurring chemical entities which are mobilized by man’s activities. In the marine environment, the fate of pollutants is largely determined by biogeochemical process. Some of these chemical changes enhance the toxicity of the pollutants. Other chemical changes cause the degradation or immobilization of pollutants and, as a result, act to purify the waters. Possible fates for PAHs, released into the environment, include volatilization, photo-oxidation, chemical oxidation, bioaccumulation and adsorption on soil particles, leaching, and microbial degradation. Elevated concentrations of polycyclic aromatic hydrocarbons (PAHs) have been found in mangrove sediments due to anthropogenic compounds

Characteristics of dibenzothiophene desulfurization by Rhodococcus erythropolis R1 and its Dsz-negative mutant

Introduction: Biodesulfurization is used as a selective method for lowering the sulfur content of petroleum products. Materials and methods: A sulfur-oxidation bacterial strain named Rhodococcus erythropolis R1 (NCBI GenBank Accession No. GU570564) was used in this study for desulfurization of dibenzothiophene (DBT). Results: The induced culture of strain R1 was able to produce 2-hydroxybiphenyl (2- HBP) from DBT followed 4S pathway without further degrading carbon backbone. This process confirmed by gas chromatography (GC) analysis. The specific activity of DBT desulfurization by R1 was 45 µM (g dry wt)-1 h-1. The addition of Tween 80 as surfactant and glycerol as carbon source determines a 100% rate of DBT-desulfurization during 3 days. The heavy plasmid detected in R1 strain carries dsz genes responsible for biodesulfurization of DBT that was shown by PCR reaction. The mutant strains which had lost this plasmid also had lost desulfurization phenotype. Both mutant and wild strain were sensitive to high concentration of 2-HBP and some antibiotics. Discussion and conclusion: Strain R1 desulfurize DBT through the sulfur-specific degradation pathway or 4S pathway with the selective cleavage of carbon-sulfur (C-S) bonds without reducing the energy content. Addition of surfactant enhanced the desulfurization of DBT by increasing its bioavailability and also could improve the growth and desulfurization rate. The location of desulfurization genes was on a heavy plasmid in strain R1. Based on the results of this study, R. erythropolis R1 could serve as a model system for efficient biodesulfurization of petroleum oil without reducing the energy value

Microbial Bioremediation of Petroleum Hydrocarbon– Contaminated Marine Environments

Petroleum pollution has become a serious environmental problem, which can cause harmful damage to the environment and human health. This pollutant is introduced into the environment from both natural and anthropogenic sources. Various physicochemical and biological treatments were developed for the cleanup of contaminated environments. However, bioremediation is based on the metabolic capabilities of microorganisms, and it is considered as the most basic and reliable way to eliminate contaminants, particularly petroleum and its recalcitrant compounds. It is more effective alternative comparing to classical remediation techniques. A high diversity of potential hydrocarbon degrader’s microorganisms was reported, and bacteria constitute the most abundant group, which has been well studied for hydrocarbon degradation. Several bioremediation approaches through bioaugmentation or/and biostimulation have been successfully applied. The interest on the optimizing of different parameters to achieve successful bioremediation technologies has been increased. In this chapter, we summarize the diversity and the hydrocarbon degradation potential of microorganism involved in the remediation of contaminated environments. We also present an overview of the efficient bioremediation strategies used for the decontamination of polluted marine environments

Innovative, ecofriendly biosorbent-biodegrading biofilms for bioremediation of oil- contaminated water

Immobilization of microorganisms capable of degrading specific contaminants significantly promotes bioremediation processes. In this study, innovative and ecofriendly biosorbent-biodegrading biofilms have been developed in order to remediate oil-contaminated water. This was achieved by immobilizing hydrocarbon-degrading gammaproteobacteria and actinobacteria on biodegradable oil-adsorbing carriers, based on polylactic acid and polycaprolactone electrospun membranes. High capacities for adhesion and proliferation of bacterial cells were observed by scanning electron microscopy. The bioremediation efficiency of the systems, tested on crude oil and quantified by gas chromatography, showed that immobilization increased hydrocarbon biodegradation by up to 23 % compared with free living bacteria. The resulting biosorbent biodegrading biofilms simultaneously adsorbed 100 % of spilled oil and biodegraded more than 66 % over 10 days, with limited environmental dispersion of cells. Biofilm-mediated bioremediation, using eco-friendly supports, is a low-cost, low-impact, versatile tool for bioremediation of aquatic systems

Assessing the Impact of Hg-Contaminated Sediments Washing through Sentinel Species: A Mesocosm Approach

This study combines a traditional chemical characterization with a simultaneous biological evaluation through histological, immunohistochemical, and enzymatic observations to assess the efficiency and sustainability of soil washing on Hg-contaminated sediment in terms of the bioavailability of the contaminant before and after the treatment, as well as the potential drawbacks of the treatment that are not revealed by a simple chemical characterization of treated sediments on its own. Different extracting agents, that is, ethylenedinitrilotetraacetic acid (EDTA), ethylenediaminedisuccinic acid (EDDS), sodium thiosulfate, potassium iodide (KI), and iodine (I2), have been compared in this work to evaluate their efficiency in the removal of Hg from contaminated sediments. Speciation analysis was applied to assess the mobility of Hg from different fractions of aged sediments. Biological evaluation was carried out through the use of large mesocosms and Mytilus galloprovincialis as biological sentinels. Results from bench scale tests have shown Hg removal of up to 93% by means of the multi-step KI/I2 washing process of the sediment. Results from histological, immunohistochemical, and enzymatic analysis have shown significant differences in the degree of alteration of biological tissues and their functional integrity between organisms in contact with contaminated and restored sediments. The reduction in 5-HT3R immunopositivity in the mesocosm with treated sediments suggests a tendency for mussels to recover a healthy condition. This result was also confirmed by the measurement of the enzymatic activity of AChE in mussel gills, which was significantly reduced in organisms from the mesocosm with polluted sediments compared with those from the one with restored sediments. The proposed approach could help stakeholders all over the world select, at an early stage, the most efficient cleaning action from a more holistic perspective, including not only pollutant concentration and economic reduction but also a direct assessment of the ultimate impact of the selected process on the biological system

Impact of using yeast derivatives on the development of atypical aging in wines

Yeast derivatives (YDs) are commercial products obtained from yeast colonies grown in bioreactors then inactivated and dried. They are employed in winemaking to supply nitrogen (N), enhance yeast growth and remove unwanted compounds. Since glucose is the primary carbon and energy source for yeast growth, agricultural byproducts are commonly used in their production. Atypical aging (ATA) is a wine aroma defect arising from the oxidation of indole-3-acetic acid (IAA) to 2-aminoacetophenone (AAP). It entails the appearance of unpleasant odours as well as the rapid loss of varietal aromas. As IAA is one of the main plant hormones and YDs are often manufactured using material of plant origin, it can be assumed that AAP precursors are contained in those commercial formulations. If this is the case, the use of YDs could potentially increase the risk of obtaining ATA-tainted wines. To explore this hypothesis, 28 YDs were screened for the presence of AAP-related compounds, as well as their amino acidic content. Since several ATA precursors were detected, fermentation experiments were carried out in which different amounts of YD were added to different grape musts. Interestingly, depending on the nature of the commercial formulation, AAP development was observed to be either enhanced or diminished. More specifically, as well as concentration of AAP and precursors, the presence of cell walls within the YDs seemed to have an influence on the development of this defect. Furthermore, as diammonium phosphate (DAP) is also used to provide grape must with N, the effect of supplementing must with DAP was investigated. The addition of increasing doses of DAP did not significantly affect the accumulation of AAP. These results are very promising for both winemakers and YD producers, and they highlight the need for further research on the use of YDs in oenolog