Degradation and mineralization of high-molecular-weight polycyclic aromatic hydrocarbons by defined fungal-bacterial cocultures
Boonchan, S and Britz, ML and Stanley, GA, Degradation and mineralization of high-molecular-weight polycyclic aromatic hydrocarbons by defined fungal-bacterial cocultures, Applied and Environmental Microbiology, 66, (3) pp. 1007-1019. ISSN 0099-2240 (2000) [Refereed Article]
This study investigated the biodegradation of high-molecular-weight polycyclic aromatic hydrocarbons (PAHs) in liquid media and soil by bacteria (Stenotrophomonas maltophilia VUN 10,010 and bacterial consortium VUN 10,009) and a fungus (Penicillium janthinellum VUO 10,201) that were isolated from separate creosote- and manufactured-gas plant-contaminated soils. The bacteria could use pyrene as their sole carbon and energy source in a basal salts medium (BSM) and mineralized significant amounts of benzo[a]pyrene cometabolically when pyrene was also present in BSM. P. janthinellum VUO 10,201 could not utilize any high-molecular-weight PAH as sole carbon and energy source but could partially degrade these if cultured in a nutrient broth. Although small amounts of chrysene, benz[a]anthracene, benzo[a]pyrene, and dibenz[a,h]anthracene were degraded by axenic cultures of these isolates in BSM containing a single PAH, such conditions did not support significant microbial growth or PAIl mineralization. However, significant degradation of, and microbial growth on, pyrene, chrysene, benz[a] anthracene, benzo[a] pyrene, and dibenz[a,h] anthracene, each as a single PAIl in BSM, occurred when P. janthinellum VUO 10,201 and either bacterial consortium VUN 10,009 or S. maltophilia VUN 10,010 were combined in the one culture, i.e., fungal- bacterial cocultures: 25% of the benzo[a]pyrene was mineralized to CO2 by these cocultures over 49 days, accompanied by transient accumulation and disappearance of intermediates detected by high-pressure liquid chromatography. Inoculation of fungal-bacterial cocultures into PAH- contaminated soil resulted in significantly improved degradation of high- molecular-weight PAHs, benzo [a] pyrene mineralization (53% of added [14C] benzo [a] pyrene was recovered as 14CO2 in 100 days), and reduction in the mutagenicity of organic soil extracts, compared with the indigenous microbes and soil amended with only axenic inocula.