Studi condotti negli ultimi anni hanno prodotto nuove evidenze su come i microrganismi degradano alcani (Rojo, 2009). Tuttavia, alcuni aspetti rimangono poco conosciuti. Uno tra questi è come gli alcani permeino le membrane o come siano trasportati nella cellula. Gli enzimi per la degradazione degli alcani a bassa e media catena di atomi di carbonio sono piuttosto ben caratterizzati. Tuttavia sono stati scoperti nuovi enzimi coinvolti nella degradazione di alcani a lunga catena (C20 – C50). Diversi studi riportano indizi sulla presenza di idrossilasi non ancora caratterizzati (Rojo, 2009).
Il presente lavoro di tesi necessita quindi di ulteriori esperimenti per approfondire la conoscenza sul consorzio batterico autoctono e sui nove morfotipi isolati.
A tal proposito sarà opportuno effettuare una ulteriore caratterizzazione dei ceppi batterici isolati, tramite fishing PCR dipendente di geni diversi da alkB coinvolti nel processo di ossidazione degli alcani lineari e/o nel co - metabolismo degli stessi alcani lineari e di altre strutture idrocarburiche, quali gli alcani non lineari ed eventuali frazioni nafteniche e naftaleniche che consentano, grazie all’uso di primer degenerati ricavati in letteratura, di amplificare geni come almA o citocromo P450. Sarà effettuato un eventuale loro clonaggio e progettazione di marker molecolari che, in combinazione con alkB, possano offrire un robusto strumento per il monitoraggio dei morfotipi di interesse per prove di bioaugmentation in matrici reali in trattamento.
Gli step successivi prevedranno una sperimentazione in mesocosmo, necessaria per la simulazione dei processi di biorisanamento attuati per matrici ambientali quali i sedimenti di dragaggio in esame. La sperimentazione in mesocosmo consentente il monitoraggio continuo dei parametri chimico – fisici (pH, temperatura, contenuto idrico) e biologici (carica batterica, processi degradativi) su scala reale.
La sperimentazione in mesocosmo è quindi finalizzata all’allestimento di un impianto di biopila (strategia di trattamento biologico off site che prevede che la matrice da trattare venga posta in cumuli coperti in cui parametri chimico – fisici come aerazione,
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apporto di nutrienti, pH, temperatura e disponibilità di acqua sono mantenuti costanti). Il processo sarà monitorato in termini di diminuzione della contaminazione fino al raggiungimento dei limiti di legge e sarà validato in termini di assessment tossicologico.
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