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Hyperhomocysteinemia is a well established risk factor for atherothrombotic disease, and the request for homocysteine determinations and the number of laboratories that need to perform this assay to assess individual risk profile is increasing. Different methods to evaluate homocysteine plasma levels are at present available. In the present study three methods, an in-house high-pressure liquid chromatographic (HPLC) method (considered as reference method) and two commercial immunoassays, an enzyme-linked immunoassay (EIA) and an automated fluorescence polarization immunoassay (FPIA), were used to measure homocysteine plasma levels in 100 samples. The median of homocysteine plasma levels obtained by HPLC was 9.0 micromol/L (range 4.2-23.0); the median of values obtained by EIA and FPIA were 10.6 micromol/L (range 3.3-21.5) and 9.6 micromol/L (4.8-20.2), respectively. The FPIA method showed the lowest within-run and between-run coefficients of variation (3.6% and 4.1%, respectively). There was a significant correlation between EIA and HPLC (r=0.81; p0.0001), and between FPIA and HPLC (r=0.85; p0.0001). The Bland-Altman analysis showed that FPIA agreed best with HPLC; EIA displayed a relatively wide scatter of difference data points. The present results indicate that the technological characteristics of the FPIA assay make this method suitable for the determination of Hcy in clinical laboratories.

In this paper comparative genome and phenotype microarray analyses of Rhodococcus sp. BCP1 and Rhodococcus opacus R7 were performed. Rhodococcus sp. BCP1 was selected for its ability to grow on short-chain n-alkanes and R. opacus R7 was isolated for its ability to grow on naphthalene and on o-xylene. Results of genome comparison, includ- ing BCP1, R7, along with other Rhodococcus reference strains, showed that at least 30% of the genome of each strain presented unique sequences and only 50% of the predicted proteome was shared. To associate genomic features with metabolic capabilities of BCP1 and R7 strains, hundreds of different growth conditions were tested through Phenotype Microarray, by using Biolog plates and plates manually prepared with additional xenobiotic compounds. Around one-third of the surveyed carbon sources was utilized by both strains although R7 generally showed higher metabolic activity values compared to BCP1. More- over, R7 showed broader range of nitrogen and sulphur sources. Phenotype Microarray data were combined with genomic analysis to genetically support the metabolic features of the two strains. The genome analysis allowed to identify some gene clusters involved in the metabolism of the main tested xenobiotic compounds. Results show that R7 contains multi- ple genes for the degradation of a large set of aromatic and PAHs compounds, while a lower variability in terms of genes predicted to be involved in aromatic degradation was found in BCP1. This genetic feature can be related to the strong genetic pressure exerted by the two different environment from which the two strains were isolated. According to this, in the BCP1 genome the smo gene cluster involved in the short-chain n-alkanes degradation, is included in one of the unique regions and it is not conserved in the Rhodo- coccus strains compared in this work. Data obtained underline the great potential of these two Rhodococcus spp. strains for biodegradation and environmental decontamination processes.

Rhodococcus sp. strain BCP1 (DSM 44980) co-metabolizes chlorinated compounds and mineralizes a broad range of alkanes being highly tolerant to these toxic chemicals. Here, we present the high-quality draft genome sequence of strain BCP1 consisting of 6,231,823 bp, with a G+C content of 70.4%, 5,902 protein-coding genes, and 58 RNAs genes. Rhodococcus genus comprises Gram-positive, non-sporulating, aerobic bacteria that are widely distributed in the environment (1). Rhodococcus sp. strain BCP1 (formerly: Rhodococcus aetherovorans strain BCP1, DSM 44980) was selected from an aerobic butane-utilizing consortium as the prevailing isolate able to co-metabolize chloroform, vinyl chloride and trichloroethylene (2, 3). As BCP1 also catabolizes a wide range of aliphatic, alicyclic and carboxylated alkanes, it represents a strain of considerable environmental and industrial interest (4). The genome sequencing of Rhodococcus sp. BCP1 was performed using 454 sequencing technology (Roche GS FLX Titanium). The total number of sequence reads were 668,686 from one shotgun library and 353,744 from one paired-end library (8-kb inserts). All the reads were assembled using Newbler 2.6 into 123 contigs with an N50 length of 237,787 bp and an average genome coverage of 65x. Based on paired-end directional information, the contigs were further ordered into 3 scaffolds, giving a total genome size of 6.2 Mb with a G+C content of 70.4%.

Staphylococcus aureus is the major causative agent of skin and soft tissue infections, whose prevention and treatment have become more difficult due to the emergence of antibiotic-resistant strains. In this regard, the development of an effective treatment represents a challenge that can be overcome by delivering new antibiofilm agents with appropriate nanocarriers. In this study, a biosurfactant (BS) isolated from Lactobacillus gasseri BC9 and subsequently loaded in liposomes (LP), was evaluated for its ability to prevent the development and to eradicate the biofilm of different methicillin resistant S. aureus (MRSA) strains. BS from L. gasseri BC9 was not cytotoxic and was able to prevent formation and to eradicate the biofilm of different MRSA strains. BS loaded liposomes (BS-LP) presented a mean diameter (lower than 200 nm) suitable for topical administration and a low polydispersity index (lower than 0.2) that were maintained over time for up 28 days. Notably, BS-LP showed higher ability than free BS to inhibit S. aureus biofilm formation and eradication. BS-LP were loaded in lyophilized matrices able to quickly dissolve (dissolution time lower than 5 s) upon contact with exudate, thus allowing vesicle reconstitution. In conclusion, in this work, we demonstrated the antibiofilm activity of Lactobacillus-derived BS and BS-LP against clinically relevant MRSA strains. Furthermore, the affordable production of lyophilized matrices containing BS-LP for local prevention of cutaneous infections was established.

The outbreak of SARS-CoV-2 pandemic highlighted the worldwide lack of surgical masks and personal protective equipment, which represent the main defense available against respiratory diseases as COVID-19. At the time, masks shortage was dramatic in Italy, the first European country seriously hit by the pandemic: aiming to address the emergency and to support the Italian industrial reconversion to the production of surgical masks, a multidisciplinary team of the University of Bologna organized a laboratory to test surgical masks according to European regulations. The group, driven by the expertise of chemical engineers, microbiologists, and occupational physicians, set-up the test lines to perform all the functional tests required. The laboratory started its activity on late March 2020, and as of the end of December of the same year 435 surgical mask prototypes were tested, with only 42 masks compliant to the European standard. From the analysis of the materials used, as well as of the production methods, it was found that a compliant surgical mask is most likely composed of three layers, a central meltblown filtration layer and two external spunbond comfort layers. An increase in the material thickness (grammage), or in the number of layers, does not improve the filtration efficiency, but leads to poor breathability, indicating that filtration depends not only on pure size exclusion, but other mechanisms are taking place (driven by electrostatic charge). The study critically reviewed the European standard procedures, identifying the weak aspects; among the others, the control of aerosol droplet size during the bacterial filtration test results to be crucial, since it can change the classification of a mask when its performance lies near to the limiting values of 95 or 98%.

A full-arch rehabilitation of the edentulous upper jaw without grafting procedures exploits the residual alveolar or the basal bone, with the necessity of long implants placed with a particular orientation. The precision in planning and placing the fixtures is fundamental to avoid clinical problems and to allow an acceptable connection with the prosthesis. The computer-aided implantology resulted in more accuracy than the traditional one, with a high standard of correspondence between the virtual project and the real outcome. This paper reports about the two different digital protocols, static and dynamic, as support to implant-borne prosthetic rehabilitation of edentulous maxillae. Two pterygoid and two/four anterior standard implants were seated in both cases by two different operators, without flap raising, and immediately loaded. This approach avoided the posterior cantilever by-passing the maxillary sinus and was adequately planned and realized without any surgical or prosthetic error. The two digital flow-charts were described step by step, underlining each other’s advantages and drawbacks compared to a free-hand approach.

In an aquifer-aquitard system in the subsoil of the city of Ferrara (Emilia-Romagna region, northern Italy) highly contaminated with chlorinated aliphatic toxic organics such as trichloroethylene (TCE) and tetrachloroethylene (PCE), a strong microbial-dependent dechlorination activity takes place during migration of contaminants through shallow organic-rich layers with peat intercalations. The in situ microbial degradation of chlorinated ethenes, formerly inferredby the utilization of contaminant concentration profiles and Compound-Specific Isotope Analysis (CSIA), was here assessed using Illumina sequencing of V4 hypervariable region of 16S rRNA gene and by clone library analysis of dehalogenase metabolic genes. Taxon-specific investigation of the microbial communities catalyzing the chlorination process revealed the presence of not only dehalogenating genera such as Dehalococcoides and Dehalobacter but also of numerous other groups of non-dehalogenating bacteria and archaea thriving on diverse metabolisms such as hydrolysis and fermentation of complex organic matter, acidogenesis, acetogenesis, and methanogenesis, which can indirectly support the reductive dechlorination process. Besides, the diversity of genes encoding some reductive dehalogenases was also analyzed. Geochemical and 16S rRNA and RDH gene analyses, as a whole, provided insights into the microbial community complexity and the distribution of potential dechlorinators. Based on the data obtained, a possible network of metabolic interactions has been hypothesized to obtain an effective reductive dechlorination process.

Pleurotus ostreatusdual biofilms with bacteria are known to be involved in rock phosphate solubilization, endophytic colonization, and even in nitrogen fixation. Despite these relevant implications, no information is currently available on the architecture ofP. ostreatus-based dual biofilms. In addition to this, there is a limited amount of information regarding the estimation of the temporal changes in the relative abundances of the partners in such binary systems. To address these issues, a dual biofilm model system with this fungus was prepared by usingPseudomonas alcaliphila34 as the bacterial partner due to its very fast biofilm-forming ability. The application of the bacterial inoculum to already settled fungal biofilm on a polystyrene surface coated with hydroxyapatite was the most efficient approach to the production of the mixed system the ultrastructure of which was investigated by a multi-microscopy approach. Transmission electron microscopy analysis showed that the adhesion of bacterial cells onto the mycelial cell wall appeared to be mediated by the presence of an abundant layer of extracellular matrix (ECM). Scanning electron microscopy analysis showed that ECM filaments of bacterial origin formed initially a reticular structure that assumed a tabular semblance after 72 h, thus overshadowing the underlying mycelial network. Across the thickness of the mixed biofilms, the presence of an extensive network of channels with large aggregates of viable bacteria located on the edges of their lumina was found by confocal laser scanning microscopy; on the outermost biofilm layer, a significant fraction of dead bacterial cells was evident. Albeit with tangible differences, similar results regarding the estimation of the temporal shifts in the relative abundances of the two partners were obtained by two independent methods, the former relying on qPCR targeting of 16S and 18S rRNA genes and the latter on ester-linked fatty acid methyl esters analysis.

This paper presents a route for the treatment of MSWI fly (FA) and bottom ashes (BA) using microorganisms to critically assess whether bioleaching is within reach of effective industrial application. The leaching of metals from BA and FA was investigated in a controlled laboratory environment using a culture isolated from a natural system where the dominant strains are acidophilic bacteria, mainly Acidothiobacillus thiooxidans and Acidothiobacillus ferrooxidans. The community of microorganisms (mostly acidophilic, S- and Fe-oxidizing bacteria) was collected directly from overflows and ponds at the sediment–water interface of a natural system near a post-mining site. Pre-cultivation was done in 250 mL flasks followed by the adaptation to the different substrates (both FA and BA). The effect of different material pre-treatment and elemental sulphur concentrations were evaluated for both BA and FA, at a starting pH of 4. The bioleaching of BA and FA substrates experienced good yields of metal extraction with an optimum duration of two weeks. The results showed that more than 90% Zn, Cu, and 10% Pb are removed from FA; while 100% Cu, 80% Zn and 20% Pb are removed from BA samples. Batch experiments with regenerating ion-exchange resins did not perform well for metal recovery, but could serve as a valuable decontamination step. The techniques used here with FA and BA can be used for urban mining purposes (e.g. ashes and other meal-rich anthropogenic wastes), but also low-grade ores in the mining industry, contributing to resource recovery or decontamination agendas.

Naphthenic acids (NAs) are an important group of toxic organic compounds naturally occurring in hydrocarbon deposits. This work shows that Rhodococcus aetherivorans BCP1 cells not only utilize a mixture of eight different NAs (8XNAs) for growth but they are also capable of marked degradation of two model NAs, cyclohexanecarboxylic acid (CHCA) and cyclopentanecarboxylic acid (CPCA) when supplied at concentrations from 50 to 500 mgL−1 . The growth curves of BCP1 on 8XNAs, CHCA, and CPCA showed an initial lag phase not present in growth on glucose, which presumably was related to the toxic effects of NAs on the cell membrane permeability. BCP1 cell adaptation responses that allowed survival on NAs included changes in cell morphology, production of intracellular bodies and changes in fatty acid composition. Transmission electron microscopy (TEM) analysis of BCP1 cells grown on CHCA or CPCA showed a slight reduction in the cell size, the production of EPS-like material and intracellular electrontransparent and electron-dense inclusion bodies. The electron-transparent inclusions increased in the amount and size in NA-grown BCP1 cells under nitrogen limiting conditions and contained storage lipids as suggested by cell staining with the lipophilic Nile Blue A dye. Lipidomic analyses revealed significant changes with increases of methyl-branched (MBFA) and polyunsaturated fatty acids (PUFA) examining the fatty acid composition of NAs-growing BCP1 cells. PUFA biosynthesis is not usual in bacteria and, together with MBFA, can influence structural and functional processes with resulting effects on cell vitality. Finally, through the use of RT (Reverse Transcription)- qPCR, a gene cluster (chcpca) was found to be transcriptionally induced during the growth on CHCA and CPCA. Based on the expression and bioinformatics results, the predicted products of the chcpca gene cluster are proposed to be involved in aerobic NA degradation in R. aetherivorans BCP1. This study provides first insights into the genetic and metabolic mechanisms allowing a Rhodococcus strain to aerobically degrade NAs.&nbsp

In a healthy host, a balance exists between members of the microbiota, such that potential pathogenic and non-pathogenic organisms can be found in apparent harmony. During infection, this balance can become disturbed, leading to often dramatic changes in the composition of the microbiota. For most bacterial infections, nonspecific antibiotics are used, killing the non- pathogenic members of the microbiota as well as the pathogens and leading to a substantial delay in the restoration of a healthy microbiota. Lactobacillus species dominate the vaginal niche of healthy reproductive age women and are involved in the homeostasis maintenance by preventing the overgrowth of urogenital pathogens. Lactobacilli play key protective roles through different mechanisms such as production of various antimicrobial compounds, co-aggregation, competitive exclusion, immunomodulation and release of biosurfactants (BS). Aim of the study was to investigate the ability of vaginal lactobacilli to produce Biosurfactants (BS), as well as to characterize BS in terms of anti-adhesive and anti-biofilm activities against some representative vaginal pathogens. Production of BS was evaluated by the oil displacement test, which is an indirect, sensitive and simple method for the measurement of molecules’ surface activity. Several lactobacilli strains produced significant amount of biosurfactants: BS produced by L. gasseri BC9 showed the best surface tension at both the highest (10 mg/ml) and the lowest (1.3 mg/ml) concentration. Anti- adhesive and anti-biofilm activities of BS produced by L. gasseri BC9 was evaluated against strains of Staphylococcus aureus and Escherichia coli, respectively. In conclusion, BS isolated from L. gasseri BC9 strain showed antibacterial properties against S. aureus. BS from BC9 strain also displayed anti-adhesive and anti-biofilm abilities mainly against S. aureus. Together, these capabilities may open up possibilities for BS as an alternative therapeutic approach for the prevention and/or treatment of Gram positive hospital-acquired infections.

In the present study, the response of Rhodococcus aetherivorans BCP1 and Rhodococcus opacus R7 to various stress conditions and several antimicrobials was examined by PM in relation with genetic determinants, as revealed by annotation analysis of the two genomes. Comparison between metabolic activities and genetic features of BCP1 and R7 provided new insight into the environmental persistence of these two members of the genus Rhodococcus. (C) 2016 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

The reactions between [Fe 6 C(CO) 16 ] 2− and CuCl, in refluxing THF, yield [Fe 5 C(CO) 14 (CuCl)] 2− ( 1 ), [Fe 4 C(CO) 12 (CuCl) 2 ] 2− ( 2 ), or [{Fe 4 Cu 2 C(CO) 12 (μ-Cl)} 2 ] 2− ( 3 ), depending on the Fe 6 /CuCl ratio. The chloro ligands of these clusters can be displaced either spontaneously, or by metal-assisted substitution, to give the bromo derivative [Fe 5 C(CO) 14 (CuBr)] 2− ( 4 ) or the solvento complexes [Fe 5 C(CO) 14 (CuTHF)] − ( 5 ) and [Fe 4 C(CO) 12 (CuNCMe) 2 ] ( 6 ). The latter can be also obtained directly, by metal substitution from [Fe 6 C(CO) 16 ] 2− and [Cu(NCMe) 4 ]BF 4 , or by polyhedral expansion from [Fe 4 C(CO) 12 ] 2− . All the clusters are octahedral, with the copper atoms in a pseudo-linear geometry, where one of the coordination positions is occupied by the interstitial carbide. The two copper atoms in the Fe 4 Cu 2 clusters are always in cis geometry and, in the dimer [{Fe 4 Cu 2 C(CO) 12 (μ-Cl)} 2 ] 2− , they are joined through chlorides. The role of the different metal centres in determining the redox activity of the heteronuclear Fe–Cu clusters 1 , 2 , 3 , has been studied by electrochemical methods. In the bridged dimer 3 , the two Fe 4 Cu 2 C cluster units resulted electronically not communicating.

Polychlorinated biphenyls (PCBs) are ubiquitous persistent organic pollutants that can be co-metabolically biotransformed by biphenyl-utilizing bacteria. In this study, terminal-restriction fragment length polymorphism (T-RFLP) was applied to the substrate specificity-determining region of the 2,3-biphenyl dioxygenase encoding genes of a microbial community found in a PCB-polluted soil. Notably, both the total biphenyl/PCB-utilizing community and its members actively expressing the 2,3-biphenyl dioxygenase gene were analyzed. T-RFLP fingerprinting along with gene library construction allowed us not only to detect biphenyl dioxygenases related to the well characterized catabolic patterns of Pseudomonas pseudoalcaligenes KF707 and Burkholderia xenovorans LB400, but also to reveal novel environmental enzyme classes displaying amino acid substitutions that may be related to broader specificity and improved catalytic properties. Furthermore, space and time of sampling along with bioavailability conditions of different PCBs were considered possible sources of profile variability.

none 7 si Rhodococcus sp. strain BCP1 was initially isolated for its ability to grow on gaseous n-alkanes, which act as inducers for the co-metabolic degradation of low-chlorinated compounds. Here, both molecular and metabolic features of BCP1 cells grown on gaseous and short-chain n-alkanes (up to n-heptane) were examined in detail. We show that propane metabolism generated terminal and sub-terminal oxidation products such as 1- and 2-propanol, whereas 1-butanol was the only terminal oxidation product detected from n-butane metabolism. Two gene clusters, prmABCD and smoABCD—coding for Soluble Di-Iron Monooxgenases (SDIMOs) involved in gaseous n-alkanes oxidation—were detected in the BCP1 genome. By means of Reverse Transcriptase-quantitative PCR (RT-qPCR) analysis, a set of substrates inducing the expression of the sdimo genes in BCP1 were assessed as well as their transcriptional repression in the presence of sugars, organic acids, or during the cell growth on rich medium (Luria–Bertani broth). The transcriptional start sites of both the sdimo gene clusters were identified by means of primer extension experiments. Finally, proteomic studies revealed changes in the protein pattern induced by growth on gaseous- (n-butane) and/or liquid (n-hexane) short-chain n-alkanes as compared to growth on succinate. Among the differently expressed protein spots, two chaperonins and an isocytrate lyase were identified along with oxidoreductases involved in oxidation reactions downstream of the initial monooxygenase reaction step. Martina Cappelletti;Alessandro Presentato;Giorgio Milazzo;Raymond J. Turner;Stefano Fedi;Dario Frascari;Davide Zannoni Martina Cappelletti;Alessandro Presentato;Giorgio Milazzo;Raymond J. Turner;Stefano Fedi;Dario Frascari;Davide Zannoni

Tellurite (TeO3(2-)) is the most toxic and soluble oxyanion among tellurium (Te) compounds. The effects of the metalloid anion on the oxidative stress response of the obligate aerobe Pseudomonas pseudoalcaligenes KF707 were investigated. Cells treated with sub-lethal concentrations of TeO3(2-) showed neither adaptation to it nor cross-protection against oxidants such as 1,1'-4,4'-bipyridinium dichloride (paraquat, PQ2+), diazenedicarboxylic acid bis-N,N-dimethylamide (diamide), tert-butyl hydroperoxide (tBH) and hydrogen peroxide (H2O2). Notably, TeO3(2-) exerted a synergic effect on the toxicity of these latter oxidants. Tellurite was shown to decrease the cellular content of reduced thiols (RSH) with a consequent increase in the production of reactive oxygen species (ROS) and stimulation of the superoxide dismutase (SOD) activity. However, since the time course of ROS production by TeO3(2) (t1/2 > 30 min) was much slower than that with PQ2+ and/or diamide (t1/2

The anionic cluster [Pt(19)(CO)(22)](4-) (1), of pentagonal symmetry, reacts with CO and AuPPh(3)(+) fragments. Upon increasing the Au:Pt(19) molar ratio, different species are sequentially formed, but only the last two members of the series could be characterized by X-ray diffraction, namely, [Pt(19)(CO)(24)(μ(4)-AuPPh(3))(3)](-) (2) and [Pt(19)(CO)(24){μ(4)-Au(2)(PPh(3))(2)}(2)] (3). The metallic framework of the starting cluster is completely modified after the addition of CO and AuL(+), and both products display the same platinum core of trigonal symmetry, with closely packed metal atoms. The three AuL(+) units cap three different square faces in 2, whereas four AuL(+) fragments are grouped in two independent bimetallic units in the neutral cluster 3. Electrochemical and spectroelectrochemical studies on 2 showed that its redox ability is comparable with that of the homometallic 1.

Questo lavoro descrive la produzione di idrogeno per digestione anaerobica di siero di latte, glucosio e melasso utilizzando 4 ceppi Thermotoga termofili. Tutte i 4 ceppi di Thermotoga testati (T. neapolitana, T. maritima, T. naphtophila, T. petrophila) sono stati in grado di produrre H2 dal siero di latte, glucosio e melasso, sia in prove con biomassa sospese che adesa. Con tutti i tre substrati, le migliori prestazioni sono state ottenute con T. neapolitana. Sono state condotte alcuni test per selezionare il supporto ottimale per le condizioni con biomassa adesa. Sono stati testati 4 tipi di supporti, 3 in vetro sinterizzato e uno in materiale ceramico; il supporto scelto è stato Biomax.

Pseudomonas pseudoalcaligenes KF707 is a soil polychlorinated biphenyl (PCB) degrader, able to grow both planktonically and as a biofilm in the presence of various toxic metals and metalloids. Here we report the genome sequence (5,957,359 bp) of P. pseudoalcaligenes KF707, which provides insights into metabolic degradation pathways, flagellar motility, and chemotaxis.

Trattasi del primo report sulla annotazione del genoma del batterio Pseudomonas pseudoalcaligenes KF707. I dati sono stati sottoposti a pubblicazione on-line e saranno presto messi a disposizione di tutti i ricercatori interessati alla mappa genenica di questo microrganismo

A histidine-kinase cheA gene in Pseudomonas pseudoalcaligenes KF707 plays a central role in the regulation of metabolic responses as well as in chemotaxis. Non-chemotactic mutants harboring insertions into the cheA gene were screened for their ability to form biofilms in the Calgary biofilm device. Notably, ≥95% decrease in the number of cells attached to the polystyrene surface was observed in cheA mutants compared to the KF707 wild-type biofilm phenotype. The ability to form mature biofilms was restored to wild-type levels, providing functional copies of the KF707 cheA gene to the mutants. In addition, phenotype micro-arrays and proteomic analyses revealed that several basic metabolic activities and a few periplasmic binding proteins of cheA mutant cells differed compared to those of wild-type cells. These results are interpreted as evidence of a strong integration between chemotactic and metabolic pathways in the process of biofilm development by P. pseudoalcaligenes KF707.

Sustainable hydrogen production is a topic of great interest since hydrogen is considered a clean, high-energy content and a low emission fuel. According to this, biological hydrogen production, especially from organic residues, is an attractive process, combining clean energy generation with waste material recycling[1]. Since hydrogen fermentative production at high temperature benefits of general and thermodynamics advantages, hyperthermophilic Thermotoga species are considered ideal organisms for H2 production[2]. The aim of this study is to investigate the feasibility of a cost-effective process of biological H2 production from food industry wastes under thermophilic conditions. The H2-producing performances of 4 Thermotoga strains (Th. neapolitana, Th. petrophila, Th. naphtophila, Th. maritima) were compared at 77 °C by means of tests conducted in 120-mL batch bioreactors containing 40 mL of a nutrient-rich growth medium (ATCC 1977)[3] supplemented with glucose, molasses or whey as main carbon sources. For all the substrates tested, Th. neapolitana resulted the best-performing strain, with a H2 specific production rate of 0.50-0.68 mmol gdry weight-1 h-1 at a 10 g L-1 initial substrate concentration. The H2-producing capacities of the 4 strains were also evaluated under biofilm-growth conditions by using a porous ceramic support utilized in the field of biofiltration as biomass carrier. Also under attached-growth conditions, Th. neapolitana resulted the best strain for all the 3 substrates tested, with a H2 specific production rate of 0.09-0.18 mmol gdry weight-1 h-1. Further tests were aimed at optimizing the growth medium composition. As a result, a significantly more simple – and thus more economical – medium was obtained that allowed the development of a more cost-effective process, even though the resulting H2 production rates were lower than those obtained by growing Thermotoga on the rich medium ATCC 1977. Finally, the preliminary results of a kinetic study of H2 production by attached cells of Th. neapolitana with glucose, molasses and whey indicated a substrate inhibition effect above 20 g L-1 for glucose and whey, but not for molasses.

This work represents the first step of a wider study aimed at evaluating the feasibility of a cost-effective process of biological H2 production from food industry wastes under thermophilic conditions. The H2-producing performances of 4 Thermotoga strains (Th. neapolitana, Th. petrophila, Th. naphtophila, Th. maritima) were compared at 77 °C by means of tests conducted in 120-mL batch bioreactors containing 40 mL of a nutrient-rich growth medium (ATCC 1977; Van Ooteghem et al., Biotechnol. Lett., 2004, 26:1223) additioned with glucose, molasses or whey as carbon source. For all the substrate tested, Th. neapolitana resulted the best-performing strain, with a 0.50-0.68 mmol gdry weight-1 h-1 H2 specific production rate at a 10 g L-1 initial substrate concentration. To compare the H2-producing capacities of the 4 strains also under attached-growth conditions, preliminary tests were conducted with Th. neapolitana, with the goal to select the best biomass carrier among 4 porous materials utilized in the field of biofiltration. The best results were obtained with a porous ceramic product characterized by a 9 m2 g-1 interfacial area. Also under attached-growth conditions, Th. neapolitana resulted the best strain for all the 3 substrates tested, with a 0.09-0.18 mmol gdry weight-1 h-1 H2 specific production rate. Further tests aimed at optimizing the growth medium composition allowed the attainment of H2 production rates slightly lower than the above-reported values, with a significantly more simple – and thus more economical – medium composition. The preliminary results of a kinetic study of H2 production by attached cells of Th. neapolitana with glucose, molasses and whey indicate a substrate inhibition effect above 20 g L-1 for glucose and whey, but not for molasses. Finally, the process scale-up to an innovative 19-L attached-cell agitated reactor is in progress.

The reaction between [Fe2Ir2(CO)12]2− and diphenylacetylene in refluxing CH3CN yields the substituted cluster [Fe2Ir2(CO)10(PhC2Ph)]2− (1). In the crystals, the four metal atoms define a butterfly arrangement whose Ir–Ir hinge is parallel to the acetylenic C2 unit. The neutral triangular cluster [FeIr2(CO)9(PhC2Ph)] (2) is obtained by the treatment of 1 with acids at room temperature; in this 48 valence electrons species, the C–C and the Ir–Ir bonds are also parallel, in the μ 3 – η ∥ 2 coordination mode. The cluster [Fe2Rh(CO)10]− reacts with diphenylacetylene in refluxing THF yielding [Fe2Rh(CO)8(PhC2Ph)]− (3). In this 46 C.V.E.’s cluster, the C2 unit is perpendicular to the Fe–Fe edge, exemplifying the μ 3 – η ⊥ 2 bonding mode. According to 13C NMR spectra, the structure of the three clusters is maintained in solution. Electrochemical investigations show that the one-electron oxidation of [Fe2Ir2(CO)10(L)]2− (L = 2CO, PhC2Ph) as well as the one-electron reduction of [Fe2Rh(CO)8(PhC2Ph)]− only generates the respective short lived products.

The susceptibility to various biocides was examined in planktonic cells and biofilms of the obligate aerobe, PCBs degrader, Pseudomonas pseudoalcaligenes KF707. The toxicity of two antibiotics, amikacin and rifampicin, three metalloid oxyanions (AsO2 −, SeO3 2−, TeO3 2−) and three metal cations (Cd2+, Ni2+, Al3+) was tested at two stages of the biofilm-development (4 and 24 h) and compared to planktonic cells susceptibility. Mature biofilms formed in rich (LB, Luria–Bertani) medium were thicker (23 μm) than biofilms grown in minimal (SA saccarose-arginine) medium (13 μm). Early grown (4 h) SA-biofilms, which consisted of a few sparse/attached cells, were 50–100 times more resistant to antibiotics than planktonic cells. Conversely, minor changes in tolerance to metal(loid)s were seen in both SA- and LB-grown biofilms. In contrast to planktonic cells, no reduction of TeO3 2− to elemental Te(0) or SeO3 2− to elemental Se(0) was seen in KF707 biofilms. The data indicate that: (a) metal tolerance in KF707 biofilms, under the growth and exposure conditions described here, is different than antibiotic tolerance; (b) KF707 planktonic cells and biofilms, are almost equally susceptible to killing by metal cations and oxyanions, and (c) biofilm-tolerance to TeO3 2− and SeO3 2− is not linked to metalloid reduction; this means that KF707 planktonic cells and biofilms differ in their physiology and strategy to counteract metalloid toxicity.

The focus of this microcosm study was to monitor the performances of 17 butane-utilizing microcosms during a long-term (100-250 days) aerobic cometabolic depletion of chloroform (CF). The depletion of the contaminant began after a lag-time variable between 0 and 23 days. All microcosms quickly reached a pseudo steady-state condition, in terms of biomass concentration (with an average of 9.3 x 106 CFU ml(-1)), chloroform depletion rate (5 micromol l(-1) d(-1)) and butane utilization rate (730 micromol l(-1) d(-1)). After about 100 days of CF depletion, a sudden 5- to 7-fold increase of the chloroform rate was observed in two microcosms, where the highest amount of contaminant had been depleted. In one of these high-performing microcosms, an experiment of chloroform depletion in the absence of butane resulted in the depletion of a surprisingly high amount of contaminant (765 micromolCF kg(-1) dry soil in 2 months) and in a marked selection of a single bacterial strain. Bioaugmentation assays conducted with the biomass selected in this microcosm and with a pure culture of the selected strain immediately resulted in very high chloroform depletion rates. Preliminary results of a study conducted with resting cells of the selected strain indicated that it can degrade chloroform concentrations up to 119 microM (14.2 mg l(-1)) without any sign of substrate toxicity, and that it is able to transform vinyl chloride and 1,1,2-trichloroethane.

In this microcosm study we have monitored the performances of 12 butane-utilizing consortia during a long-term aerobic cometabolic degradation of chloroform (CF). After approximately 100 days of continuous CF depletion, a sudden improvement of the biodegradative performances (7-fold increase of chloroform degradation rate) was observed in two microcosms in which the highest amount of depleted CF (> 70 mg / kg of dry soil) was observed. Two bacterial strains, isolated from the CF-degrading microcosms, were identified as belonging to the genera Rhodococcus and Stenotrophomonas, respectively. A strain, named F, was further characterized to establish the involvement of the butane-monooxygenase in CF degradation.

The effect of several operational conditions on the adaptation of indigenous biomasses was investigated in a microcosms study of chloroform (CF) cometabolic degradation with butane. The objective was to minimize the duration of the adaptation phase and the amount of growth substrate to provide in field applications. The adaptation to butane and CF was monitored at 5 concentrations of butane (1.50, 1.00, 0.50, 0.25 and 0.10 mg/L), at 3 concentrations of CF (1, 5 and 10 mg/L), at 4 temporal sequences of exposition to butane (continuous, 5 h/d, 7 h/d, 24 h every other day) and at 3 temperatures (15, 25 and 30°C). The results indicate that the most favorable condition for the adaptation of indigenous biomasses consists in the continuous exposition to a very low concentration of growth substrate (0.1 mg/L). In all the tests the degradation of CF started within 48 days. The microbiological characterization of the consortia indicated that the prolonged degradation of CF led to the selection of 3 specific butane-utilizing strains.

This study shows that the oxyanion tellurite TeO32- can be used as a tool to detect and quantify the release in soil microcosms of Pseudomonas pseudoalcaligenes KF707, a strain spontaneously resistant to tellurite with a minimal inhibitory concentration (MIC) of 150 μg ml-1. KF707 cells which carry the genes for degradation of a wide range of polychlorinated biphenyl congeners (PCBs) were used for inoculation of laboratory microcosms prepared with two different PCB-contaminated soils (Ci/s and Di/s) in the presence or absence of biphenyl as carbon source. In all microcosms supplemented with biphenyl, significant survival of strain KF707 was noted over a time period of 35 days; conversely, in microcosms containing Ci/s soil without biphenyl addition a rapid decrease in KF707 inoculated cells was observed. By comparing the number of inoculated KF707 cells with the number of indigenous bacteria growing on biphenyl (IBGB) of both Ci/s and Di/s microcosms, it could be concluded that the KF707/IBGB ratio is a relevant parameter in determining the fate of the added strain. The efficacy of potassium tellurite as a selective marker to monitor strain KF707 in laboratory microcosms was confirmed by ARDRA analyses of the 16S rDNA, while the isolated indigenous bacteria growing on biphenyl were identified as members of three different species of the genus Pseudomonas. We also report that in microcosms inoculated with KF707 cells in the absence of biphenyl, only low chlorinated biphenyls were degraded. © 2002 Éditions scientifiques et médicales Elsevier SAS. All rights reserved.