Effects of media composition on substrate removal by pure and mixed bacterial cultures.
Continuous culture experiments with identical experimental designs were run with a mixed microbial community of activated sludge origin and an axenic bacterial culture derived from it. Each culture received 2-chlorophenol (2-CP) at a concentration of 160 mg/L as COD and L-lysine at a concentration of 65 mg/L as COD. A factorial experimental design was employed with dilution rate and media composition as the two controlled variables. Three dilution rates were studied: 0.015, 0.0325, and 0.05 h-1. Media composition was changed by adding four biogenic compounds (butyric acid, thymine, glutamic acid and lactose) in equal COD proportions at total concentrations of 0, 34, 225, and 1462 mg/L as COD. The measured variables were the effluent concentrations of 2-CP as measured by the 4-aminoantipyrene test and lysine as measured by the o-diacetylbenzene procedure. The results suggest that community structure and substrate composition play important roles in the response of a microbial community to mixed substrates. The addition of more biogenic substrates to the axenic culture had a deleterious effect on the removal of both lysine and 2-CP, although the effect was much larger on lysine removal. In contrast, additional substrates had a positive effect on the removal of 2-CP by the mixed community and much less of a negative effect on the removal of lysine. The dilution rate at which the cultures were growing had relatively little impact on the responses to the additional substrates.
Grady
C P
CP
L.G. Rich Environmental Research Laboratory, Clemson University, SC 29634-0919.
Cordone
L
L
Cusack
L
L
D001419:Bacteria / Q000378:metabolism*; D001673:Biodegradation, Environmental; D001709:Biotechnology / Q000379:methods*; D002733:Chlorophenols / Q000378:metabolism*; D003470:Culture Media; D007700:Kinetics; D008239:Lysine / Q000378:metabolism*; D008954:Models, Biological
D002733:Chlorophenols; D003470:Culture Media; D008239:Lysine; C030683:2-chlorophenol