peptones and gamma-resorcylic-acid

This study evaluated the kinetics of simultaneous biodegradation of peptone mixture and 2,6-dihydroxybenzoic acid (2,6-DHBA) by an acclimated dual microbial culture under aerobic conditions. A laboratory-scale sequencing batch reactor was sustained at steady-state with peptone mixture feeding. During the study period, peptone mixture feeding was continuously supplemented with 2,6-DHBA. Related experimental data were derived from three sets of parallel batch reactors, the first fed with the peptone mixture, the second with 2,6-DHBA and the third one with the two substrates, after acclimation of microbial culture and simultaneous biodegradation of both organics. A mechanistic model was developed for this purpose including the necessary model components and process kinetics for the model calibration of relevant experimental data. Model evaluation provided all biodegradation characteristics and kinetics for both peptone mixture and 2,6-DHBA. It also supported the development of a dual microbial community through acclimation, with the selective growth of a second group of microorganisms specifically capable of metabolizing 2,6-DHBA as an organic carbon source.

Topics: Acclimatization; Bacteria; Biodegradation, Environmental; Biological Oxygen Demand Analysis; Biomass; Bioreactors; Calibration; Computer Simulation; Hydroxybenzoates; Kinetics; Models, Biological; Oxygen; Peptones; Polyhydroxyalkanoates

This study investigated the fate of 2,6-dihydroxybenzoic acid in a mixed microbial culture acclimated to peptone under aerobic conditions. A laboratory-scale sequencing batch reactor receiving a pulse feeding of peptone at the start of each daily cycle was used for this purpose. Experimental evaluations interpreted changes induced by continuous benzoic acid additions on the oxygen uptake rate profiles associated with peptone biodegradation. At first exposure, 2,6-dihydroxybenzoic acid reduced the activity of the mixed culture and impaired peptone biodegradation. Around one-third of peptone removed could be utilized for microbial metabolism. With continuous feeding the mixture culture became acclimated and simultaneously removed peptone and 2,6-dihydroxybenzoic acid. After 30 days, oxygen uptake rate tests performed separately on peptone, 2,6-dihydroxybenzoic acid and the substrate mixture supported the existence of a dual biomass restructured with the selective growth of another group of microorganisms capable of utilizing 2,6-dihydroxybenzoic acid as an organic carbon source.

Topics: Bacteria, Aerobic; Benzoic Acid; Biodegradation, Environmental; Bioreactors; Chromatography, Gas; Hydroxybenzoates; Oxygen Consumption; Peptones; Sewage; Spectrophotometry, Ultraviolet; Time Factors

The study evaluated the response of an enriched microbial culture on 2,6-dihydroxybenxoic acid (2,6-DHBA) and peptone mixture at low sludge age (theta(X)) under aerobic conditions. It emphasized the effect of culture history by comparing the response of the microbial culture sustained at identical conditions but at two different theta(X) of 2 and 10 days. The fate and impact of continuous 2,6-DHBA addition were evaluated by means of changes induced on the oxygen uptake rate profiles. The acute impact of 2,6-DHBA drastically changed with the culture history. It only inhibited the utilization of the readily biodegradable COD fraction but maintained the overall stoichiometry of substrate removal at a theta(X) of 2 days, while blocking microbial activity with only partial substrate utilization when the theta(X) was 10 days. After four days of continuous 2,6-DHBA feeding, the microbial culture was acclimated providing simultaneous removal for peptone and 2,6-DHBA. The acclimation period was apparently a function of the theta(X) and it was shorter than 10 days. Evaluation of the oxygen uptake rate profiles indicated that acclimation resulted in the development of a dual microbial community with the selective growth of another group of biomass equipped with the enzymatic tools for utilizing 2,6-DHBA as an organic carbon source.

Topics: Aerobiosis; Biodegradation, Environmental; Hydroxybenzoates; Peptones; Sewage; Time Factors

This study evaluated the kinetics of 2,6-dihydroxybenozic acid and peptone biodegradation at low sludge age by acclimated culture under aerobic conditions. A laboratory-scale sequencing batch reactor was set and fed with peptone mixture. The system was operated at steady-state at a sludge age of 2 days. In order to assess biodegradation kinetics of 2,6-dihydroxybenozic acid and its impact on peptone utilization, a mixture of 2,6-dihydroxybenzoic acid and peptone was fed to mixed culture. After a period of four days, the system became acclimated to simultaneously remove both 2,6-dihydroxybenzoic acid and peptone mixture. A mechanistic model was developed involving model components and kinetic parameters for both substrates. This model was calibrated with related experimental data such as oxygen uptake rate and COD. Biodegradation characteristics and kinetics of peptone and 2,6-dihydroxybenzoic acid was estimated. The evaluation of calibrated model indicated that a group of microorganisms adjusted their enzymatic tools for the utilization of 2,6-dihydroxybenzoic acid resulting in dual microbial community development at low sludge age.

Topics: Acclimatization; Aerobiosis; Biodegradation, Environmental; Hydroxybenzoates; Kinetics; Microbiological Techniques; Oxygen; Peptones; Sewage