The biodegradation of valeric, butyric, propionic and acetic acids in anoxic, subsurface, soil environments

The biodegradation potential of two subsurface soils was characterized by monitoring the biodegradation of short-chain fatty acids in anaerobic soil microcosms. Valerate, butyrate, propionate, and acetate concentrations were monitored independently using separate microcosms. The effect of sulfate on the microbial communities was also investigated.

One soil, from Newport News, Virginia, consisted of a sandy loam collected beneath a low lying, grassy field. The microcosms containing the soil were characterized by: a neutral pH, the utilization of sulfate with concomitant precipitation of iron sulfide , an increase in the degradation rate as a result of sulfate addition, and a production of bicarbonate directly related to acid mineralization.

Another soil, from Blacksburg, Virginia, consisted of a silty-clay collected beneath a wooded hilltop. Microcosms containing the soil were characterized by : a pH between 4 and 5, little sulfate utilization with no visible iron sulfide precipitation, an increase in degradation rates upon the addition of sulfate, and little or no accumulation of bicarbonate.

These results indicate that short-chain fatty acids are readily degraded in subsurface anaerobic soil systems and that these rates are dependent on the availability of electron acceptors and the diversity of the indigenous population.