Filomena Sannino

Dephenolisation of olive mill waste-waters by olive husk

Olive mill waste-waters (OMWW) are a by-product of olive-oil production and a major environmental problem in the Mediterranean area. The use of a polyphenol-oxidase from olive husk is proposed for the enzymatic removal of low-molecular phenolics in OMWW. For comparison purposes, a purified microbial polyphenol-oxidase (Trametes versicolor laccase) was also employed. Though both enzymatic systems show relevant activity towards phenol polymerization, olive husk is much more appealing in view of possible applications because of its availability and extremely low cost, associated with excellent enzymatic activity and specificity.

Microbial Conversion of Olive Oil Mill Wastewaters into Lipids Suitable for Biodiesel Production

Lipomyces starkey were able to survive and proliferate in the presence of olive oil mill wastewaters (OMW), a medium difficult to process by biological treatments, due to the antimicrobial activities of their phenolic components. The microorganisms were grown in the presence of undiluted OMW, without external organic supplements, producing a significant reduction of both the total organic carbon (TOC) and the total phenols content. The OMW treated by L. starkey showed a significant increase of the germination index. The preliminary dilution of OMW enhanced the reduction of polluting components of OMW, leading to a complete TOC removal, as well as to lower levels of residual phenols. The activities of extracellular lipases and esterases significantly increased in the course of the OMW fermentation. A significant increase in lipid yield was observed in L. starkey in the course of the OMW treatment, particularly enhanced when the feedstock was preliminarily diluted. The fatty acid distribution showed a prevalence of oleic acid, demonstrating the potential of L. starkeyi as a source of lipids to be used as a feedstock for the synthesis of II generation biodiesel.

Anti-biofilm activity of the Antarctic marine bacterium Pseudoalteromonas haloplanktis TAC125.

Considering the increasing impact of bacterial biofilms on human health, industrial and food-processing activities, the interest in the development of new approaches for the prevention and treatment of adhesion and biofilm formation capabilities has increased. A viable approach should target adhesive properties without affecting bacterial vitality in order to avoid the rapid appearance of escape mutants. It is known that marine bacteria belonging to the genus Pseudoalteromonas produce compounds of biotechnological interest, including anti-biofilm molecules. Pseudoalteromonas haloplanktis TAC125 is the first Antarctic Gram-negative strain whose genome was sequenced. In this work the anti-biofilm activity of P. haloplanktis supernatant was examined on different staphylococci. Results obtained demonstrated that supernatant of P. haloplanktis, grown in static condition, inhibits biofilm of Staphylococcus epidermidis. In order to define the chemical nature of the biofilm-inhibiting compound, the supernatant was subject to various treatments. Data reported demonstrated that the biologically active component is sensible to treatment with sodium periodate suggesting its saccharidic nature.

A Unique Capsular Polysaccharide Structure from the Psychrophilic Marine Bacterium Colwellia psychrerythraea 34H That Mimics Antifreeze (Glyco)proteins

The low temperatures of polar regions and high-altitude environments, especially icy habitats, present challenges for many microorganisms. Their ability to live under subfreezing conditions implies the production of compounds conferring cryotolerance. Colwellia psychrerythraea 34H, a γ-proteobacterium isolated from subzero Arctic marine sediments, provides a model for the study of life in cold environments. We report here the identification and detailed molecular primary and secondary structures of capsular polysaccharide from C. psychrerythraea 34H cells. The polymer was isolated in the water layer when cells were extracted by phenol/water and characterized by one- and two-dimensional NMR spectroscopy together with chemical analysis. Molecular mechanics and dynamics calculations were also performed. The polysaccharide consists of a tetrasaccharidic repeating unit containing two amino sugars and two uronic acids bearing threonine as substituent. The structural features of this unique polysaccharide resemble those present in antifreeze proteins and glycoproteins. These results suggest a possible correlation between the capsule structure and the ability of C. psychrerythraea to colonize subfreezing marine environments.

Methylobacterium populi VP2: Plant Growth-Promoting Bacterium Isolated from a Highly Polluted Environment for Polycyclic Aromatic Hydrocarbon (PAH) Biodegradation

The use of microorganisms to accelerate the natural detoxification processes of toxic substances in the soil represents an alternative ecofriendly and low-cost method of environmental remediation compared to harmful incineration and chemical treatments. Fourteen strains able to grow on minimal selective medium with a complex mixture of different classes of xenobiotic compounds as the sole carbon source were isolated from the soil of the ex-industrial site ACNA (Aziende Chimiche Nazionali Associate) in Cengio (Savona, Italy). The best putative degrading isolate, Methylobacterium populi VP2, was identified using a polyphasic approach on the basis of its phenotypic, biochemical, and molecular characterisation. Moreover, this strain also showed multiple plant growth promotion activities: it was able to produce indole-3-acetic acid (IAA) and siderophores, solubilise phosphate, and produce a biofilm in the presence of phenanthrene and alleviate phenanthrene stress in tomato seeds. This is the first report on the simultaneous occurrence of the PAH-degrading ability by Methylobacterium populi and its multiple plant growth-promoting activities. Therefore, the selected indigenous strain, which is naturally present in highly contaminated soils, is good candidate for plant growth promotion and is capable of biodegrading xenobiotic organic compounds to remediate contaminated soil alone and/or soil associated with plants.

Formation and characterization of OH-Al-humate- montmorillonite complexes

Abstract We studied the formation of OH–Al–humate–montmorillonite complexes as affected by the nature of the humic acid and the sequence of addition of montmorillonite, humic acid and hydrolytic species of Al. Complexes were prepared at pH 7.0 by different addition sequences of montmorillonite, 3 or 6 mmol Al and 5, 10 or 20 mg of humic acid per g of clay. d-spacings of samples ranged from 14.50 to 19.00 A vs. 11.70 A of montmorillonite. Interlayering of humic acids was promoted when preformed OH–Al–humate complexes were added to montmorillonite and partially impeded when the complexes were synthesized by neutralizing Al ions in the presence of montmorillonite. Humic acids were not interlayered in the absence of OH–Al-species, indicating that the hydrolytic products of Al play a vital role in the formation of organo–mineral complexes in natural environment.

Sorption Capacity of Mesoporous Metal Oxides for the Removal of MCPA from Polluted Waters

A study was performed to assess the sorption capacity of the phenoxy acid herbicide, MCPA, on two mesoporous oxides, Al(2)O(3) and Fe(2)O(3,) by using a batch equilibrium method. Effects of pH, contact time, initial concentration and sorbent dosage on the sorption of the herbicide were investigated. The collected data evidenced the greater sorption efficiency of Al(2)O(3) with respect to Fe(2)O(3). These results can be explained by considering the specific mesoporous structure of Al(2)O(3) together with the greater value of surface area. MCPA is assumed to be bound to Al(2)O(3) and Fe(2)O(3) by a combination of ionic and ion-dipole bonding. Both oxides present as sorbents for a fast and highly efficient removal of MCPA from contaminated waters. For the first time the possible use of mesoporous metal oxides to remove MCPA from contaminated wastewaters identifies these sorbents as suitable filters for the decontamination of point sources.

Cyclic process of simazine removal from waters by adsorption on zeolite H-Y and its regeneration by thermal treatment

Removal of the agrochemical simazine from polluted waters through adsorption by zeolite Y in its protonic form was studied. The investigated parameters were: pH, time, initial simazine concentration and solid/liquid ratio. An iterative process of simazine removal from waters is proposed, featuring: (i) final agrochemical concentration well below 0.05 mg/dm(3), the maximum concentration allowed by Italian laws in wastewaters; (ii) regeneration of the adsorbent by a few minutes thermal treatment in air at about 500°C, which results in the combustion of simazine without damage of the adsorbent; (iii) destruction of the agrochemical compound by combustion.

Remediation of Waters Contaminated with MCPA by the Yeasts Lipomyces starkeyi Entrapped in a Sol-Gel Zirconia Matrix

A single-stage sol-gel route was set to entrap yeast cells of Lipomyces starkeyi in a zirconia (ZrO(2)) matrix, and the remediation ability of the resulting catalyst toward a phenoxy acid herbicide, 4-chloro-2-methylphenoxyacetic acid (MCPA), was studied. It was found that the experimental procedure allowed a high dispersion of the microorganisms into the zirconia gel matrix; the ZrO(2) matrix exhibited a significant sorption capacity of the herbicide, and the entrapped cells showed a degradative activity toward MCPA. The combination of these effects leads to a nearly total removal efficiency (>97%) of the herbicide at 30 °C within 1 h incubation time from a solution containing a very high concentration of MCPA (200 mg L(-1)). On the basis of the experimental evidence, a removal mechanism was proposed involving in the first step the sorption of the herbicide molecules on the ZrO(2) matrix, followed by the microbial degradation operated by the entrapped yeasts, the metabolic activity of which appear enhanced under the microenvironmental conditions established within the zirconia matrix. Repeated batch tests of sorption/degradation of entrapped Lipomyces showed that the removal efficiency retained almost the same value of 97.3% after 3 batch tests, with only a subsequent slight decrease, probably due to the progressive saturation of the zirconia matrix.

Remediation of highly contaminated soils from an industrial site by employing a combined treatment with exogeneous humic substances and oxidative biomimetic catalysis

Remediation of two polluted soils from a northern Italian industrial site heavily contaminated with organic contaminants was attempted here by subjecting soils first to addition with an exogenous humic acid (HA), and, then, to an oxidation reaction catalyzed by a water-soluble iron-porphyrin (FeP). An expected decrease of detectable organic pollutants (>50%) was already observed when soils were treated only with the H2O2 oxidant. This reduction was substantially enhanced when oxidation was catalyzed by iron-porphyrin (FeP+H2O2) and the largest effect was observed for the most highly polluted soil. Even more significant was the decrease in detectable pollutants (70-90%) when soils were first amended with HA and then subjected to the FeP+H2O2 treatment. This reduction in extractable pollutants after the combined HA+FeP+H2O2 treatment was due to formation of covalent CC and COC bonds between soil contaminants and amended humic molecules. Moreover, the concomitant detection of condensation products in soil extracts following FeP addition confirmed the occurrence of free-radical coupling reactions catalyzed by FeP. These findings indicate that a combined technique based on the action of both humic matter and a metal-porhyrin catalyst, may become useful to quantitatively reduce the toxicity of heavily contaminated soils and prevent the environmental transport of pollutants.