Quantitative proteome profiles help reveal efficient xylose utilization mechanisms in solventogenic Clostridium sp. strain BOH3

Abstract

Development of sustainable biobutanol production platforms from lignocellulosic materials is impeded by inefficient five carbon sugar uptake by solventogenic bacteria. The recently isolated Clostridium sp. strain BOH3 is particularly advantaged in this regard as it serves as a model organism which can simultaneously utilize both glucose and xylose for high butanol (>15 g/L) production. Strain BOH3 was, therefore, investigated for its metabolic mechanisms for efficient five carbon sugar uptake using a quantitative proteomics based approach. The proteomics data show that proteins within the CAC1341-1349 operon play a pivotal role for efficient xylose uptake within the cells to produce butanol. Furthermore, up-regulation of key enzymes within the riboflavin synthesis pathway explained that xylose could induce higher riboflavin production capability of the bacteria (e.g., ∼80 mg/L from glucose vs. ∼120 mg/L from xylose). Overall results from the present experimental approach indicated that xylose-fed BOH3 cultures are subjected to high levels of redox stress which coupled with the solvent stress-trigger a sporulation response within the cells earlier than the glucose-fed cultures. The study lays the platform for metabolic engineering strategies in designing organisms for efficient butanol and other value-added chemicals such as riboflavin production. Biotechnol. Bioeng. 2017;114: 1959-1969. © 2017 Wiley Periodicals, Inc.

A Novel Platform for Evaluating the Environmental Impacts on Bacterial Cellulose Production

“…Both dyes intercalate with DNA. Propidium iodide penetrates only dead bacterial cells resulting in red fluorescence while Syto9 stains live bacteria green 12 – 15 .…”

Sporulation in solventogenic and acetogenic clostridia

“…The sporulation is known to be a response to stressful conditions. The primary triggers of sporulation in Bacillus species have been shown to be nutrient starvation and high cell density (Awang et al 1992;Basu et al 2017). In contrast to bacilli, where the cessation of growth occurs due to a lack of nutrients, in Clostridium, an excess of a carbon or nitrogen source led to growth cessation (Dürre 2005; U.…”

“…The substrate may also accelerate sporulation initiation. For instance, xylose-fed cultures of C. acetobutylicum BOH3 sporulated earlier than glucose-fed cultures (Basu et al 2017). In addition to the nature of the carbohydrate, its concentration also affects sporulation.…”

Quantitative proteomic analysis to reveal expression differences for butanol production from glycerol and glucose by Clostridium sp. strain CT7

“…In addition, the phage shock protein (psp) system is a specialized extracytoplasmic stress response one through lowering proton motive force (PMF) within bacteria. Psp system has been reported to be the pivotal component of signal transduction pathway, which helps to maintain the integrity of cytoplasmic membrane and interact with proteins responsible for proton transportation using proton gradient or ATP [33][34][35]. The down-regulation of pspA in glycerol-fed strain 6 Comparison expression profiles of key proteins related with butanol production fed with glycerol and glucose in different time course CT7 was observed at both early and late fermentation stages, indicating that more psp proteins were induced in glucose-fed ones to resist the environmental stress, maintain the integrity of cytoplasmic membrane and restore the desired PMF.…”