Abstract
The microbial biodegradation of simulated graywater, containing 21.5 mg of linear alkylbenzene sulfonate liter-1, was investigated with a continuous-flow bioreactor with 100% biomass recycle. Low concentrations of organic matter in the ultrafiltration eluate were achieved by hydraulic residence times as short as 1.6 h and for periods of up to 74 days at a hydraulic residence time of 6 h. Upon a shift from the chemostat to the biomass recycle mode, the increase in biomass with time approximated a linear rather than an exponential function. Biomass densities as high as 6.8 g of cell protein liter-1 were reached; this was 50-fold higher than the steady-state biomass level in chemostats fed the same medium. We assessed physiological changes in the microbial community after a switch from the chemostat to the biomass recycle mode. Over 150 h, there was a two- to fourfold decrease in the respiratory potential of the microbes. After this decrease, respiratory potentials were relatively constant up to 74 days of operation. A decline in reactivity was also indicated by increasing lag periods before growth in response to organic nutrient inputs and by a decrease in the proportion of cells able to reduce tetrazolium dye. However, the bioreactor system was still capable of rapidly metabolizing inputs of organic matter, because of the very high biomass concentrations. It appears that < 10% of the organic carbon inputs accumulate as biomass.
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- Chesbro W., Evans T., Eifert R. Very slow growth of Escherichia coli. J Bacteriol. 1979 Aug;139(2):625–638. doi: 10.1128/jb.139.2.625-638.1979. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cook G. M., Janssen P. H., Morgan H. W. Uncoupler-Resistant Glucose Uptake by the Thermophilic Glycolytic Anaerobe Thermoanaerobacter thermosulfuricus (Clostridium thermohydrosulfuricum). Appl Environ Microbiol. 1993 Sep;59(9):2984–2990. doi: 10.1128/aem.59.9.2984-2990.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Harder W., Dijkhuizen L. Physiological responses to nutrient limitation. Annu Rev Microbiol. 1983;37:1–23. doi: 10.1146/annurev.mi.37.100183.000245. [DOI] [PubMed] [Google Scholar]
- Jiménez L., Breen A., Thomas N., Federle T. W., Sayler G. S. Mineralization of linear alkylbenzene sulfonate by a four-member aerobic bacterial consortium. Appl Environ Microbiol. 1991 May;57(5):1566–1569. doi: 10.1128/aem.57.5.1566-1569.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
- LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
- McFeters G. A., Yu F. P., Pyle B. H., Stewart P. S. Physiological assessment of bacteria using fluorochromes. J Microbiol Methods. 1995 Jan;21(1):1–13. doi: 10.1016/0167-7012(94)00027-5. [DOI] [PubMed] [Google Scholar]
- Muller R. H., Babel W. Measurement of Growth at Very Low Rates ((mu) >= 0), an Approach To Study the Energy Requirement for the Survival of Alcaligenes eutrophus JMP 134. Appl Environ Microbiol. 1996 Jan;62(1):147–151. doi: 10.1128/aem.62.1.147-151.1996. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rodriguez G. G., Phipps D., Ishiguro K., Ridgway H. F. Use of a fluorescent redox probe for direct visualization of actively respiring bacteria. Appl Environ Microbiol. 1992 Jun;58(6):1801–1808. doi: 10.1128/aem.58.6.1801-1808.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sigoillot J. C., Nguyen M. H. Complete oxidation of linear alkylbenzene sulfonate by bacterial communities selected from coastal seawater. Appl Environ Microbiol. 1992 Apr;58(4):1308–1312. doi: 10.1128/aem.58.4.1308-1312.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
- van Verseveld H. W., Chesbro W. R., Braster M., Stouthamer A. H. Eubacteria have 3 growth modes keyed to nutrient flow. Consequences for the concept of maintenance and maximal growth yield. Arch Microbiol. 1984 Feb;137(2):176–184. doi: 10.1007/BF00414463. [DOI] [PubMed] [Google Scholar]