Microbial Insights, Inc. products

CENSUS qPCR (quantitative polymerase chain reaction) is a DNA based method to accurately quantify specific microorganisms (e.g. Dehalococcoides, Dehalobacter) and functional genes (e.g., vinyl chloride reductase, anaerobic benzene carboxylase) responsible for biodegradation of contaminants.

Detect and quantify bacteria responsible for biodegradation of Chlorinated Methanes. Chlorinated methanes including carbon tetrachloride (CT), chloroform (CF), and dichloromethane (DCM) were widely used as solvents, degreasers, fumigants, and chemical intermediates in industrial processes and now are common groundwater contaminants.  With potential adverse health effects including increased cancer risk, maximum contaminant levels (MCLs) have been esablished for carbon tetrachloride and dichloromethane. In additiona, chlorinated methanes are also common co-contaminants at tetrachlorethene (PCE) and trichloroethene (TCE) impacted sites.  The presence of carbon tetrachloride and chloroform can be especially problematic at PCE/TCE sites due to inhibition of reductive dechlorination of chlorinated ethenes (Bagley et al. 2000; Duhamel et al. 2002)

Under anaerobic conditions, pentachlorophenol (PCP) can serve as an electron acceptor for some Desulfitobacterium and Dehalococcoides species. In each case however, complete reductive dechlorination of PCP to phenol was not observed. Instead, PCP dechlorination by Dehalococcoides resulted in the production of a mixture of dichloro- and monochlorophenols. Likewise, Desulfitobacterium strain PCP-1 dechlorinates PCP to 3-chlorophenol but other Desulfitobacterium species are only capable of ortho-dechlorination. Thus the net production of lesser chlorinated phenol must be considered when evaluating reductive dechlorination as a mechanism for PCP biodegradation. QuantArray®-Chlor includes quantification of all Targets listed in the table below. Alternatively, CENSUS® qPCR can be performed to quantify a select subset such as Dehalococcoides and Desulfitobacterium.

From 1929 to 1978, polychlorinated biphenyls (PCBs) manufactured under the commercial names like Aroclor, Fenclor, Kanechlor and Phenclor were widely used as transformer and hydraulic fluids (Field and Sierra-Alvarez 2008).  Commercial PCB preparations are mixtures composed of 60 to 90 congeners with different degrees and positions of chlorine substituents.   For example, Aroclor 1242, 1248, 1254, and 1260 are PCB mixtures with average chlorine weight percentages of 42, 48, 54, and 60%.  Both the degree of chlorination and the positions of the chlorines (ortho, meta, or para) impact PCB biodegradation.  In general terms, highly chlorinated biphenyls are subject to reductive dechlorination while less heavily chlorinated congeners can be co-metabolized aerobically.  Thus, while considered persistent in part due to their hydrophobicity, PCBs can potentially be mineralized through a sequence of anaerobic-aerobic biodegradation.

Aerobic biodegradation of MTBE and the intermediate TBA has been extensively studied in the laboratory and documented in the field. However, Methylibium petroleiphilum PM1 remains one of the few bacterial cultures isolated to date that utilizes MTBE and TBA as growth supporting substrates. The key steps in aerobic MTBE/TBA biodegradation by strain PM1 is the initial oxidation mediated by a monooxygenase and the continued biodegradation of TBA catalyzed by TBA hydroxylase.

At sites impacted by petroleum products or crude, the aromatic hydrocarbons benzene, toluene, ethylbenzene, xylenes (BTEX) as well as naphthalene and other polycyclic aromatic hydrocarbons (PAHs) are often the contaminants of greatest concern. However, alkanes are typically among the most abundant fractions in crude and petroleum products like gasoline and therefore significant contributors to total petroleum hydrocarbons (TPH) at impacted sites. In addition to an assays targeting the genes encoding enzymes responsible for biodegradation of BTEX, naphthalene, and other PAHs, QuantArray®-Petro includes an assay targeting the functional gene in the pathway for anaerobic biodegradation of alkanes. Alternatively, CENSUS® qPCR can be performed to quantify only the assA gene.

Redox conditions and microbial populations are intrinsically coupled in that availability of electron acceptors influences the microbial community composition and microbial processes in turn impact site geochemistry. The link between site microbiology and geochemistry then plays a governing role in the microbial metabolism and therefore the processes responsible for contaminant biodegradation. In the most general terms, microbial metabolism is an oxidation/reduction reaction where oxidation of one compound (electron donor) is coupled to reduction of another compound (electron acceptor). Depending on the contaminant of concern and the biodegradation process involved, site contaminants can serve as either an electron donor or electron acceptor. Compounds that are already in a reduced state like BTEX and PAHs are more readily oxidized and typically serve as electron donors.

Under anaerobic conditions, chlorinated ethanes are susceptible to reductive dechlorination by several groups of halorespiring bacteria, most notably Dehalobacter and Dehalogenimonas spp., and functional genes for reductive dehalogenases continue to be identified.  Anaerobic biodegradation of 1,1,2-TCA and 1,2-DCA proceeds via dichloroelimination producing vinyl chloride and ethene, respectively.  Dehalobacter spp. have also been isolated that are capable of sequential reductive dechlorination of 1,1,1-TCA through 1,1-DCA to chloroethane. QuantArray®-Chlor includes quantification of all Targets listed in the table below including Dehalobacter, Dehalococcoides, additional halorespiring bacteria, functional genes, and competing microorganisms.  Alternatively, CENSUS® qPCR can be performed to quantify a select subset such as Dehalobacter and Dehalogenimonas.