Fermentation of oxidized hexose derivatives by Clostridium acetobutylicum

Abstract

Background: Clostridium acetobutylicum fermentations are promising for production of commodity chemicals from heterogeneous biomass due to the wide range of substrates the organism can metabolize. Much work has been done to elucidate the pathways for utilization of aldoses, but little is known about metabolism of more oxidized substrates. Two oxidized hexose derivatives, gluconate and galacturonate, are present in low cost feedstocks, and their metabolism will contribute to overall metabolic output of these substrates.

Real‐time metabolite monitoring of glucose‐fed Clostridium acetobutylicum fermentations using Raman assisted metabolomics

“…Metabolite analysis were performed as previously described using an Agilent 1200 equipped with a refractive index detector and an Aminex HPX‐87H cation exchange column (300 × 7.8 mM i.d. × 9 μm; Bio‐Rad) . That is 100‐μl samples were injected into the HPLC system and eluted isocratically with a mobile phase of 3.25 mM H 2 SO 4 at 0.6 ml/min and 30 °C.…”

“…× 9 μm; Bio-Rad). [5,40] That is 100-μl samples were injected into the HPLC system and eluted isocratically with a mobile phase of 3.25 mM H 2 SO 4 at 0.6 ml/min and 30°C. Data from Raman spectral scans were paired with analyzed HPLC data using corresponding time points (T0 through T73).…”

“…In batch culture, C. acetobutylicum initially produces acids (notably acetic and butyric) during the acidogenic growth phase. When organic acids accumulate and external pH drops down to ~4.0, the acids, along with additional carbohydrates, are converted to solvents during a second growth phase, called solventogenesis . Product distribution and yield are dependent on numerous factors including substrate, specific metabolic pathways, and the redox state of the cells .…”

“…When organic acids accumulate and external pH drops down to ~4.0, the acids, along with additional carbohydrates, are converted to solvents during a second growth phase, called solventogenesis . Product distribution and yield are dependent on numerous factors including substrate, specific metabolic pathways, and the redox state of the cells . Butanol is the most desirable end product because it can be used directly in existing fuel infrastructure with little or no modifications .…”

Structural analysis ofClostridium acetobutylicumATCC 824 glycoside hydrolase from CAZy family GH105

“…The PGA backbone is a major component of pectin (Prade et al, 1999), and thus induction of CA_C0359 on this substrate suggests that the protein might target a PGA-derived substrate. C. acetobutylicum is capable of subsisting on galacturonic acid monomers and therefore may not have a strict requirement to process polysaccharides intracellularly (Servinsky et al, 2014). In this instance, CA_C0359 would serve a redundant role to increase the speed of PGA metabolism.…”