Hexavalent chromium (Cr(VI)) is found together with a variety of aromatic compounds in a number of contaminated sites, including groundwater aquifers, lake and river sediments, and soils. Cr(VI) and its organic copollutants often originate from industrial sources such as leather tanning, photographic-film making, wood preservation, car manufacturing, petroleum refining, and agricultural activity ([http://www.ncbi.nlm.nih.gov/pubmed/11337838|Nkhalambayausi-Chirwa and Wang, 2001]). A common pathway for Cr(VI) reduction to the less toxic Cr(III) is done through the unstable Cr(V) intermediate ([http://www.ncbi.nlm.nih.gov/pubmed/11348688|Cervantes et al, 2001]). This reduction is carried out by many different chromium resistant microorganisms. A less common Cr(VI) reduction involves simultaneous Cr(VI) reduction and phenol degradation, which was observed in a fixed-film bioreactor consisting of a coculture of Pseudomonas putida DMP-1 and Escherichia coli ATCC 33456 ([http://www.ncbi.nlm.nih.gov/pubmed/11337838|Nkhalambayausi-Chirwa and Wang, 2001]). E. coli reduces Cr(VI) under both aerobic and anaerobic conditions ([http://www.ncbi.nlm.nih.gov/pubmed/8285683|Shen and Wang, 1993]), while P. putida is an obligate aerobe capable of degrading phenol (Wang Y. T. and Qu M. Substrate interactions during biodegradation of phenols by a Pseudomonas sp. Proceeding of the 65th Annual Water Environment Federation Conference and Technical Exposition (Alexandria, VA) (1992) 63.). Nkhalambayausi-Chirwa and Wang (2001) believe the spatial and physiological heterogeneity introduced within microbial communities by the formation of biofilms may enhance Cr(VI) reduction by E. coli within the quasi-anaerobic interior of the biofilm while supporting maximum growth of P. putida along the more aerobic surface layers.