Bacterial community changes with N'-N' dimethylforamide (DMF) additives during polycyclic aromatic hydrocarbons (PAH)...

This study examined the changes in the bacterial community during biodegradation of polycyclic aromatic hydrocarbon (PAH) substrate when N'-N' dimethylformamide (DMF) was added. The microbial populations that biodegrade the PAH substrate were assessed by Fluorescence in-situ hybridization (FISH) and changed from 49.45% Archaea and 49.15% Bacteria to 42.00% Archaea and 51.78% Bacteria when the PAH was supplemented with DMF. Nine microorganisms were classified as Gram-negative alpha-, beta- and gamma-Proteobacteria bacteria during biodegradation of PAH alone by the Biolog system. Incentive eleven microorganisms obtained from the PAH-DMF mixed substrate were found to be beta-, gamma-Proteobacteria bacteria, high G+C Gram-positive bacteria (HGC), low G+C Gram-positive bacteria (LGC) and there was even one Deinococcus-Thermus strain; this indicates greater biodiversity. The numbers in the Pseudomonad group were as high as 10(5)-10(6) CFU ml(-1), suggesting that this group plays an important role in PAH biodegradation. Community-Level Physiological Profiling (CLPP) and physiological characterization were different in the PAH biodegradation process with and without DMF. Utilization of the 95 carbon sources from the Biolog GN2 microtiter plate was greater during PAH biodegradation when PAH is present alone compared to that in the presence of DMF. The range of enzymatic activities during PAH biodegradation was lower in the presence of DMF. These results show that DMF should be used with caution when PAH is a substrate during laboratory or pilot biotreatability studies.