New insights into the biodegradation of thiodiglycol, the hydrolysis product of Yperite (sulfur mustard gas)

Aims: To isolate thiodiglycol (TDG)-degrading bacteria, the mustard gas hydrolysis product, and to characterize the metabolites formed and the enzymes involved in the degradation. Methods and Results: Two strains, identified as Achromobacter xylosoxydans G5 and Paracoccus denitrificans E4, isolated from a petroleum-contaminated soil, utilized TDG as sole carbon and sulfur source. During the degradation of TDG by strain E4 [(2-hydroxyethyl)thio] acetic acid (HETA), thiodiglycolic acid (TDGA) and bis-(2-hydroxyethyl)disulfide (BHEDS) were identified by gas chromatography\u2013mass spectrometry analysis, while HETA and TDGA were identified for strain G5. Two-dimensional isoelectric focussing-gel electrophoresis (2-D IEF/SDS\u2013PAGE) maps of protein extracts of P. denitrificans E4 grown on TDG showed a spot identified as a methanol dehydrogenase. Increased expression of a putative iscS gene, involved in sulfur assimilation, was observed in TDG-grown cells of A. xylosoxydans G5. Conclusions: TDG degradation by P. denitrificans E4 occurred through two pathways: one involved cleavage of the C\u2013S bond of HETA, yielding BHEDS and the other, oxidation of the alcoholic groups of TDG, yielding TDGA. The cleavage of the C\u2013S bond of TDGA gave mercaptoacetic acid, further oxidized to acetate and sulfate. Significance and Impact of the Study: Increased knowledge of TDG-degrading bacteria and the possibility of using them in a tailored-two-stage mustard gas destruction process

QUALI PROBABILITA\u2019 DI SUCCESSO HA LA FITOESTRAZIONE IN UN SUOLO CONTENENTE CENERI DI PIRITE?

Con il processo industriale per la produzione di acido solforico, che ha sfruttato per molti anni lo zolfo ottenuto durante il trattamento a caldo della pirite, si sono prodotte notevoli quantit\ue0 di scorie (ceneri), costituite principalmente da ossido di ferro (III) e contenenti arsenico, rame, zinco, piombo e cadmio. Il lavoro prende in esame un substrato costituito da ceneri di pirite miscelate a un suolo di riporto, che ha ricoperto il materiale depositato per lungo tempo in un\u2019area industriale dismessa e attualmente interessata da un progetto di phytoremediation. Obiettivo di tale tecnica \ue8 la coltivazione di piante tolleranti elevate concentrazioni di inquinanti e in grado di rimuoverli dal substrato. Condizione indispensabile per un buon esito della fitoestrazione \ue8 pertanto lo sviluppo di estesi apparati radicali. Per valutare la fattibilit\ue0 di questa tecnica di biorisanamento, diventa quindi importante conoscere preliminarmente, e ove possibile correggere, eventuali anomalie chimiche e fisiche del suolo, la biodisponibilit\ue0 degli inquinanti, nonch\ue9 il grado di compromissione biologica del suolo, analizzandone le comunit\ue0 batteriche. La caratterizzazione chimica e agronomica del substrato (ceneri e suolo di riporto) ha messo in evidenza l\u2019efficacia della diluizione delle ceneri con il suolo nell\u2019attenuarne le caratteristiche negative (granulometria troppo fine e omogenea, fitotossicit\ue0 elevata), e ha evidenziato l\u2019esigenza di intervenire con una fertilizzazione organica e/o minerale per compensare la scarsit\ue0 di nutrienti. La determinazione del contenuto in arsenico e rame in forma totale, solubile in acqua e labile ha evidenziato un\u2019 elevata quota di tali contaminanti in forme insolubili, probabilmente in conseguenza di processi di adsorbimento sugli ossidi di ferro. E\u2019 stata infine analizzata, mediante tecnica DGGE, la struttura delle popolazioni coltivabili di batteri eterotrofi metalli-tolleranti e non, nonch\ue9 quella degli attinomiceti. Dalle colture di arricchimento in presenza di rame, arsenito e arseniato, nichel e zinco, sono state isolate numerose colonie. Gli isolati sono stati caratterizzati per la loro metallo resistenza ed identificati, mediante sequenziamento del 16S rDNA. Infine \ue8 stata misurata la diversit\ue0 catabolica della comunit\ue0 microbica del suolo al fine di correlare la struttura delle comunit\ue0 alla loro funzione

Valutazione della compromissione biologica di un suolo contenente ceneri di pirite in un progetto di fitorisanamento

Biological health assessment of a pyrite cinder containing soil in a phytoremediation project The applicability of phytoremediation to an industrial area where pyrite cinders from a sulphuric acid production process had been discharged for a long time was investigated . Physical and chemical analysis of pyrite cinders pointed out high levels of Cu and As together with a texture mainly based on silt and fine sand and a deficiency in plant nutrients. Plant growth limiting factors have been identified by means of physical, chemical and biological analysis carried on a mixture (1:1, w/w) of the cinders and the soil covering cinders in the polluted site Plant bioassays (watercress germination, barley root elongation, lettuce dry biomass yield) indicated, together with the high potential toxicity of cinders, a low actual toxicity, and the effectiveness of mixing them with a topsoil covering the polluted area in order to reduce phytotoxicity. Moreover, bioassays showed that manure and compost were able to improve the poor agronomic quality of the mixture. Arsenic and copper in soils can affect soil microbial function and community composition and, therefore, may have effects on soil ecosystem functioning. The microbial properties of the mixture have been investigated by analysing through a polyphasic approach the bacterial community structure and by evaluating its microbial function thorough the Community Level Physiological Profile (CLPP). The number of total and metal tolerant heterotrophs and actinomycetes was determined by the viable plate count method; species diversity of total bacterial community and of culturable fraction was investigated (DGGE). The number of culturable bacteria as well as the biodiversity degree was found to be comparable with that of different heavy metal polluted soils. CLPP showed the capability of the microbial community of degrading various sugars, amino acids and carboxylic acids but few aromatic compounds provided. The most of isolates identified by sequencing 16SrRNA gene and belonging to different genera were metal resistant Qualitative and quantitative composition of the bacterial community, its catabolic versatility together with soil positive response to amendments suggest a potential success in bioremediation technologies