Model of dissolved organic carbon distribution for substrate-sufficient continuous culture

Liu, Yu

doi:10.1002/(sici)1097-0290(19991120)65:4<474::aid-bit12>3.0.co;2-h

Cited by 5 publications

(2 citation statements)

References 23 publications

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“…The higher catabolic activity implies that the more organic carbon should go to carbon dioxide. In fact, it has been demonstrated that growth yield is a function of the ratio between carbon channeled into carbon dioxide by catabolism and that converted to biomass through anabolism in suspended culture (Liu 1999). Therefore, the observed variations in growth yield and specific INT‐dehydrogenase activity in Fig.…”

Section: Discussionmentioning

confidence: 99%

Metabolic response of biofilm to shear stress in fixed-film culture

2001

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Aims: In a bio®lm reactor, detachment force resulting from hydraulic shear is a major factor that determines the formation and structure of steady state bio®lm. The metabolic response of bio®lm to change in shear stress was therefore investigated. Methods and Results: A conventional annular reactor made of PVC was used, in which shearing over the rotating disc surface was strictly de®ned. Results from the steady state aerobic bio®lm reactor showed that the bio®lm structure (density and thickness) and metabolic behaviour (growth yield and dehydrogenase activity) were closely related to the shear stress exerted on the bio®lm. Smooth, dense and stable bio®lm formed at relatively high shear stress. Higher dehydrogenase activity and lower growth yield were obtained when the shear stress was raised. Growth yield was inversely correlated with the catabolic activity of bio®lm. The reduced growth yield, together with the enhanced catabolic activity, suggests that a dissociation of catabolism from anabolism would occur at high shear stress. Conclusions: Bio®lms may respond to shear stress by regulating metabolic pathways associated with the substrate¯ux¯owing between catabolism and anabolism. A biological phenomenon, besides a simple physical effect, is underlying the observed relation between the shear stress and resulting bio®lm structure. Signi®cance and Impact of the Study: A hypothesis is proposed that the shear-induced energy spilling would be associated with a stimulated proton translocation across the cell membrane, which favours formation of a stronger bio®lm. This research may provide a basis for experimental data on bio®lm obtained at different shear stresses to be interpreted in relation to energy.

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Section: Discussionmentioning

confidence: 99%

Metabolic response of biofilm to shear stress in fixed-film culture

2001

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“…Liu (1999) studied the dissolved organic carbon (DOC) fluxes flowing between catabolism and anabolism in substrate‐sufficient continuous culture and found that the majority of the DOC consumed was channelled into CO 2 at high residual substrate concentration. Using the data of Brooke et al .…”

Section: Discussionmentioning

confidence: 99%

A kinetic model for energy spilling-associated product formation in substrate-sufficient continuous culture

Liu

Tay

2000

J Appl Microbiol

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It has been demonstrated that excess substrate can cause uncoupling between anabolism and catabolism, which leads to energy spilling. However, the Luedeking-Piret equation for product formation does not account for the energy spillingassociated product formation due to substrate excess. Based on the growth yield and energy uncoupling models proposed earlier, a kinetic model describing energy spilling-associated product formation in relation to residual substrate concentration was developed for substrate-suf®cient continuous culture and was further veri®ed with literature data. The parameters in the proposed model are well de®ned and have their own physical meanings. From this model, the speci®c productivity of unit energy spilling-associated substrate consumption, and the maximum product yield coef®cient, can be determined. Results show that the majority of energy spilling-associated substrate consumption was converted to carbon dioxide and less than 6% was¯uxed into the metabolites, while it was found that the maximum product yield coef®cients varied markedly under different nutrient limitations. The results from this research can be used to develop the optimized bioprocess for maximizing valuable product formation.

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