Soluble microbial products (SMP) in anaerobic chemostats

Abstract

The production of soluble microbial products (SMP) in anaerobic systems was evaluated using chemostat reactors. Results from steady-state and tracer experiments with (14)C-glucose and (14)C-acetate showed that significant amounts of SMP were produced during the acidogenesis of glucose, but that SMP did not accumulate during methanogenesis from acetate. In addition, at a retention time of 40 days, SMP comprised almost all of the effluent COD from the glucose-fed chemostat. For shorter retention times, as low as 10 days, the SMP concentration remained almost constant, but its significance in the effluent COD was reduced due to the accumulation of intermediate volatile fatty acids. The results from a (14)C-tracer experiment in the glucose-fed chemostat were used to evaluate the importance of including SMP formation and degradation in kinetic modeling of the methanogenic chemostats. Three models were evaluated: a model without SMP production, a model with SMP production but no degradation, and a model with SMP production and degradation, The results of this kinetic analysis indicate that the model that includes SMP production and degradation was the only one able to adequately represent the fate of (14)C in the tracer experiment. The kinetic parameters were successfully used to predict steady-state concentrations of SMP and to characterize the formation and degradation characteristics of the SMP.

Flux and performance improvement in a submerged anaerobic membrane bioreactor (SAMBR) using powdered activated carbon (PAC)

“…Samples were analysed in duplicate for COD, glucose, VFAs and SMP. SMP concentration was determined by difference [11].…”

Effects of Bacterial Community Members on the Proteome of the Ammonia-Oxidizing Bacterium Nitrosomonas sp. Strain Is79

“…In the transcriptome of Nitrosomonas europaea, increases in transcript abundance for electron transport proteins (NADH dehydrogenase complex, ATP synthase complex, and several cytochromes, including cytochrome c 552 ) were identified as possible positive effects of co-cultivation with the NOB Nitrobacter winogradskyi (29). In addition, AOB provide organic carbon in the form of soluble microbial products to co-cultured heterotrophic bacteria (26,27,32). The positive growth response of AOB to the presence of heterotrophic bacteria could be due to a variety of compounds that may be secreted by the heterotrophic bacteria, such as organic compounds (33)(34)(35)(36), acyl-homoserine lactones (37,38), or siderophores (28).…”

Anaerobic Hydrogen Production from Sucrose Using an Acid‐Enriched Sewage Sludge Microflora

“…Acetic (HAc), propionic (HPr), and butyric (HBu) acids were the acid products produced with HBu as the major product. Ethanol was reported to be the major SMP during the anaerobic degradation of saccharide [21]. The VFA and SMP fractions in the effluent were generally found in the following order of HBu (51±75 %) > HAc (13±33 %) > HPr (6± 13 %) > ethanol (3±6 %).…”

“…VFAs are the intermediate products from the anaerobic digestion of complex organic compounds. These two groups of materials constitute the major component of the effluent from an anaerobic treatment system [21].…”