Preparation of biodegradable polyesters/high‐amylose‐starch composites by reactive blending and their characterization

Two different biodegradable polyesters [polycaprolactone (PCL) and poly(3‐hydroxybutyrate‐co‐valerate) (PHBV)] were blended with a maize starch that had high amylose content through the use different reactive approaches. The compatibilization of both systems was obtained. PCL/starch composites were obtained by the addition of a third reactive component that was able to act as a coupling agent, and the reactive interface of PHBV/starch composites was improved during blending with an organic peroxide. Thermal, morphological, and mechanical characterization showed that the compatibilized composite materials had better final proprieties than neat materials or composites prepared without compatibilization. Finally, the degradation of all prepared materials by a compost simulation test was investigated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1432–1442, 2002     

Origin of fatty acids in the body: endogenous synthesis versus dietary intakes

Fats, as fatty acids (FA), together with carbohydrates, represent a major substrate group for energy production. In contrast to carbohydrates FA are less efficiently used for energy and more easily stored in tissues. A major issue, still not completely solved, concerns the origin of FA in the organism. The two theoretical alternatives are a) endogenous de novo lipogenesis from carbohydrates, and b) supply through the diet. Various pieces of evidence indicate that the first option, while well‐documented in simple biological systems, plays a minimal role in vivo. The exogenous origin therefore represents the preferred, major route of FA supply to the body. This is also supported by the observation that only the enzymes involved in the production of long‐chain polyunsaturated FA from their precursors, and not those involved in the synthesis of the FA that are abundant in the diet, are operating in vivo. Finally, as a consequence of the load of fats in our diets, competition for esterification, and reciprocal replacements, of the unsaturated FA and FA classes, that are most abundantly provided by the diet, take place in plasma lipids.     

Effects of Cigarette Smoke on Cell Viability,Linoleic Acid Metabolism and Cholesterol Synthesis,in THP−1 Cells

Cigarette smoke (CS) contains thousands of substances, mainly free radicals that have as a target the polyunsaturated fatty acids (PUFA). Long chain PUFA are produced through elongation and desaturation reactions from their precursors; the desaturation reactions are catalyzed by different enzymes: the conversion of 18:2n-6 (linoleic acid, LA) to 18:3n-6 by Delta6 desaturase, while that of 20:3n-6 to 20:4n-6 by Delta5 desaturase. The aim of this work is to evaluate the effect of serum exposed to cigarette smoke (SE-FBS) on (1) cell viability and proliferation, (2) [1-(14)C] LA conversion and desaturase activities in THP-1 cells, a monocytic cell line. In THP-1, CS inhibits cell proliferation dose-dependently, by producing a modification in the cell cycle with a reduced number of cells in synthesis and mitosis phases at higher concentrations. CS also decreases [1-(14)C] LA conversion to its derivatives in a concentration-dependent manner, inhibiting the activities of Delta6 and mainly Delta5 desaturase. In addition, CS does not modify the incorporation of LA into various lipid classes but it reduces cholesterol synthesis from radiolabelled acetate, and increases free fatty acid, TG and CE levels. In conclusion, CS affects lipid metabolism, inhibiting LA conversion and desaturase activities. CS also shifts the "de novo" lipid synthesis from free cholesterol to TG and CE, where LA is preferentially esterified.     

Cultured phototrophic biofilms for phosphorus removal in wastewater treatment

Culture experiments with phototrophic biofilms taken from the sedimentation tank of the wastewater treatment plant at the Fiumicino Airport in Rome, Italy were carried out in a prototype continuous flow incubator. Biofilms grown at varying photosynthetic photon flux density (PPFD), temperature and flow velocity were sampled at three developmental stages to quantify biofilm dry weight, chlorophyll a concentration and total cellular phosphorus content. While no coherent significant effects by flow and temperature were evidenced, maximum biofilm dry weight and phosphorous concentration significantly increased across all featured PPFDs. Maximum chlorophyll a concentration was saturated above 60 μmol m⁻² s⁻¹. A highly significant association between organic biomass and phosphorous content was observed for most light conditions, including a larger proportional increase of phosphorus concentration with respect to chlorophyll a at high PPFD. Up to 112 mg P m⁻² d⁻¹ maximal phosphorous removal rates were achieved. Elemental analysis by energy filtering transmission electron microscopy showed subcellular localization of phosphorus, confirming the accumulation in phototrophic microorganisms in biofilms grown in high light conditions.     

Characterization and distribution of petroleum hydrocarbons and heavy metals in groundwater from three Italian tank farms

The present paper highlights the utility of petroleum chemical fingerprinting in investigating known or suspected tank farm releases. A detailed characterization of groundwater was carried out in three tank farms located in north, central and south Italy. Eighteen parent polycyclic aromatic hydrocarbons (naphthalene through coronene), n-alkanes (n-C(10) through n-C(36)), isoprenoids pristane and phytane, vanadium, nickel and lead were determined. Distribution profiles and diagnostic ratios of specific fuel constituents were studied in order to identify contamination sources. Data analysis shows that in the study sites multiple pollutant sources affecting the tank farms and the surrounding industrial areas are present. Both high concentrations of contaminants coming from fuel releases and noticeable concentrations of biogenic compounds were found. A detailed data analysis suggests the origin and the level of pollution of the three sites. The results demonstrate that threshold concentration approach is not always sufficient and it is necessary to carry out studies of contaminant distribution and their diagnostic ratios in order to perform a successful forensic investigation.     

Hybrid composite based on poly(vinyl alcohol) and fillers from renewable resources

Hybrid composite laminates consisting of polyvinyl alcohol (PVA) as continuous phase (33% by weight) and lignocellulosic fillers, derived from sugarcane bagasse, apple and orange waste (22% by weight) were molded in a carver press in the presence of water and glycerol such as platicizers agents. Corn starch was introduced as a biodegradation promoter and gluing component of the natural filler and synthetic polymeric matrix in the composite (22% by weight). The prepared laminates were characterized for their mechanical properties and degradative behavior in simulated soil burial experiments. The fibers type and content in composite impacted mechanical properties. Materials based on PVA and starch with apple wastes and sugarcane bagasse fillers were much harder (Young's Modulus respectively, 57, 171 MPa) than materials prepared with orange wastes (17 Mpa). Respirometric test revealed that soil microbes preferentially used natural polymers and low molecular weight additive as a carbon source compared to biodegradable synthetic polymer. The presence of PVA in formulations had no negative effect on the degradation of lignocellulosic fibers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Hydroxylated polychlorinated biphenyl detection based on a genetically engineered bioluminescent whole-cell sensing system

The metabolites of polychlorinated biphenyls (PCBs), such as hydroxylated PCBs (OH-PCBs), have been identified as environmental contaminants. Various studies have shown that some OH-PCBs can potentially contribute to health problems. Detection of these compounds in environmental and biological samples could provide useful information about their levels and lead to a better understanding of their apparent toxicity. To that end, we have developed a whole-cell sensing system for the detection of OH-PCBs by taking advantage of the recognition of a group of related compounds, i.e., hydroxylated biphenyls, by the product of the hbpR gene in the hbp operon from Pseudomonas azelaica strain HBP1. By fusing the luxAB genes, encoding the reporter protein bacterial luciferase, to the hbp regulator-promoter sequence, a whole-cell sensing system was developed. Here, we describe the optimization and application of this whole-cell sensing system for the detection of a model compound, 2-hydroxy-3',4'-dichlorobiphenyl. A detection limit of 1 x 10(-8) M was achieved using this system. The detection of a broad range of individual OH-PCBs as well as an OH-PCB mixture was investigated. The system can detect OH-PCBs in whole serum samples in a trace amount, which is comparable to the detection of these analytes in medium alone. We envision that the method developed can potentially be employed as a rapid and sensitive way to monitor OH-PCBs for toxicological study in the laboratory, as well as a useful tool to evaluate the presence of bioavailable OH-PCBs in natural environments.     

Construction of spores for portable bacterial whole-cell biosensing systems

Whole-cell sensing systems based on living genetically engineered bacteria are known to have high sensitivity, selectivity, and rapid response times. Although these systems have found applications in biomedical and environmental analyses, their limited shelf life and transportability still restrict their use for on-site monitoring of analytes. To that end, we have developed a new method for the long-term preservation, storage, and transport of whole-cell biosensing systems that is based on bacterial spores, a dormant form of life. Specifically, we have employed spore-forming bacteria such as Bacillus subtilis and Bacillus megaterium for development of luminescent sensing systems for two model analytes, namely, arsenic and zinc. These sensing cells were converted to spores, which can then be "revived" (germinated) at a later time to generate viable and metabolically active cells. Herein, we demonstrate that these spore-based sensing systems retained their analytical performance, in terms of detection limit, dynamic range, and reproducibility, after storage at room temperature for at least 6 and 8 months, respectively, as well as after three cycles where the cells alternated between being dormant or active, i.e., sporulation-germination cycles. The ability to cycle the sensing cells between active and dormant states prolongs the cell's lifetimes and increases their robustness and ruggedness, thus making them more amenable for field applications. In addition, the small size of spores allows for their easy transport and incorporation in miniaturized portable devices. Finally, we envision that this novel strategy could expand the use of whole-cell biosensors for on-site sensing not only in mild environments but also in harsh environments and locations where there is no easy access to a laboratory, e.g., in developing countries.     

Prevalence and Mean Intensity of Anisakidae Parasite in Seafood Caught in the Mediterranean Sea Focusing on Fish Species at Risk of Being Raw-consumed. A Meta Analysis and Systematic Review

Objective: To assess the prevalence and mean intensity of anisakids in seafood caught in the Mediterranean Sea, focusing on fish species at risk of being raw-consumed. Design: Systematic review and meta-analysis of studies published from 1960–2012. Study selection: Main criteria for the inclusion of studies were as follows: Findings of anisakid larvae, in both muscles and viscera; fish species for human consumption caught in the Mediterranean Sea; prevalence and mean intensity data for each species; and sample size equal to or more than 40 fishes. Results: Twelve studies were identified. Among these, four studies considered the following three fish species that are often consumed raw or preserved lightly, or not cooked thoroughly: anchovy, pilchard, and Atlantic mackerel. Data synthesis: All pooled analyses were based on the random-effect model. Anisakids prevalence in fish muscle was 0.64% (P < 0.0001), in viscera it was 1.34% (P < 0.0001), and overall prevalence was 0.95% (P < 0.0001). Mean intensity in muscle was 2.31 (P = 0.0083), in viscera it was 1.55 (P = 0.0174), and overall it was 1.81 (P < 0.0005). Heterogeneity indices (I²) were significantly high with the exception of viscera mean intensity. Conclusions: Anchovy, pilchard, and Atlantic mackerel have a low prevalence and mean intensity of anisakidae larvae in both viscera and muscles. Mean Intensity was also low.     

Microbial oxidation of naphthalene to cis-1,2-dihydroxy-1,2-dihydronaphthalene in a membrane bioreactor

A microbial dihydroxylation process for the production of cis-1,2-dihydroxy-1,2-dihydronaphthalene from naphthalene is reported. The oxidation reaction was initially studied in a stirred tank reactor using resting cells of a Pseudomonas fluorescens mutant, grown on glucose as carbon source and acetyl salicylate as inducer of the naphthalene dioxygenase enzymatic system. In these conditions the productivity of the system was limited by the efficiency of the oxygenation and by a reversible product inhibition phenomenon. In order to overcome the inhibitory effect of the 1,2-dihydrodiol accumulation, the biotransformations were carried out in a stirred reactor equipped with a membrane ultrafiltration device. In this way, the cells and the insoluble naphthalene were retained and recycled into the vessel, while the soluble diol was continuously removed through the membrane permeate. The diol was recovered by selective adsorption on a column packed with an adsorbent resin, allowing the rapid and direct recycle of the reaction medium back to the enzymatic reactor. This system afforded a final yield three-fold higher than that of the batch process, exhibiting a bioconversion rate of 1·3 g h⁻¹ dm⁻³ for more than 16 h of continuous working.