Petroleum products are complex mixtures of literally hundreds of aliphatic, aromatic, cyclic and heterocyclic compounds.  Moreover, even a single class of contaminants such as benzene, toluene, ethylbenzene, and xylenes (BTEX) biodegradation can proceed by a multitude of pathways under both aerobic and anaerobic conditions.  The Petroleum QuantArray has been designed to address both of these issues by providing the simultaneous quantification of the specific functional genes responsible for aerobic and anaerobic biodegradation of BTEX, PAHs and a variety of short and long chain alkanes.

As an example, consider just benzene and toluene.  Aerobic biodegradation of benzene and toluene can follow four distinct pathways initiated by ring hydroxylating monooxygenases (RMO- RDEG/PHE) that attack at the ortho, meta and para positions, or by a toluene/benzene dioxygenase (TOD) which incorporates both atoms of oxygen into the aromatic ring as shown below.  Toluene is also susceptible to a fifth aerobic pathway – monooxygenase attach at the methyl group (TOL).  Under anaerobic conditions, biodegradation of toluene and other alkyl substituted aromatics is mediated by benzylsuccinate synthase (bssA) which catalyzes the addition of fumarate onto the methyl group.  Anaerobic biodegradation of unsubstituted aromatic compounds like benzene and naphthalene however is initiated by carboxylase enzymes (abcA and ancA).