Metabolic uncoupling of Shewanella oneidensis MR‐1, under the influence of excess substrate and 3, 3′, 4′, 5‐tetrachlorosalicylanilide (TCS)

Abstract

ABSTRACT:The dissociation between catabolism and anabolism is generally termed as metabolic uncoupling. Experimentally, metabolic uncoupling is characterized by a reduction in the observed biomass yield. This condition can be brought about by: (a) excess substrate (as measured by S 0 /X 0 ), and (b) addition of chemical uncouplers such as 3, 3 0 , 4 0 , 5-Tetrachlorosalicylanilide (TCS). An empirical model is proposed to quantify the uncoupling effects of both excess substrate and uncoupler addition on the microbial cultures. Metabolic uncoupling of Shewanella oneidensis MR-1, under the influence of excess pyruvate and TCS, has been modeled using the proposed expression. The degree of uncoupling was measured as a fractional reduction in theoretical maximum observed yield. Excess substrate was observed to successively reduce biomass yield as substrate concentration was increased. In the presence of TCS, conflicting trends were obtained for number yield and protein yield. This could, in part, be attributed to the observed increase in cellular protein content upon addition of TCS. Excess substrate conditions dominated uncoupling, as compared to uncoupler addition. However, these two approaches were found to have additive effects and could, in conjunction, be employed to control biomass growth during microbial processes such as subsurface bioremediation and activated sludge treatment.

Distribution variation of a metabolic uncoupler, 2,6-dichlorophenol (2,6-DCP) in long-term sludge culture and their effects on sludge reduction and biological inhibition

“…The idea of metabolic uncoupling reduction is to dissociate the energy coupling between catabolism and anabolism, thereby a part of energy extracted from substrates is wasted through futile cycles, which leads to less production of bacterial cell mass (Rho et al, 2007). Increased attention has focused on the feasibility of using chemical uncouplers, such as chlorinated, nitrated phenols and TCS, to reduce excess sludge production from the wastewater biological treatment process (Aragon et al, 2009;Chen et al, 2006;Liu, 2000;Low et al, 2000;Saini and Wood, 2008;Yang et al, 2003). The effectiveness of para-nitrophenol (pNP) on reducing biomass production was investigated in a bench-scale activated sludge process (Low et al, 2000).…”

An Empirical Strategy for Characterizing Bacterial Proteomes across Species in the Absence of Genomic Sequences

“…Multiple genome sequences for Shewanellae were selected for proof of concept, not only because of the large number of publicly available genome sequences, but also because of the potential environmental importance of these organisms [17], [18], [19], [20], [21]. We also included sequences from two bacteria that are relatively distant from Shewanellae , i.e., Deinococcus radiodurans R1 and Salmonella enterica subsp.…”

Substrate consumption and excess sludge reduction of activated sludge in the presence of uncouplers: a modeling approach

“…Liu et al (1999) proposed a kinetic model incorporating energy spilling for substrate removal in a substratesufficient batch culture of activated sludge. Recently, Saini and Wood (2008) developed an empirical model to quantify the uncoupling effects of both excess substrate and uncoupler dose on the microbial cultures. The substrate was consumed with pure culture as three parts, including growth, maintenance, and energy spilling in that study.…”