Project description:The anaerobic plant biomass delignification was questioned till recently despite being a key process for plant cell wall degradation in anaerobic biotopes where plant debris accumulate, the carbon mineralization being the limiting step of the Carbon cycle. Besides no actors were identified till now and no data were available on this processus performed by anaerobic cellulolytic bacteria or even on its existence Using RNAseq, we here report the idenfication of secreted (including cellulosomal) enzymes, especially SGNH hydrolase family members known to be esterases but never described to act on lignin. We also propose based on our genetic, biochemical and bioinformatic approaches, a new role for the SGNHs in the remodeling of lignin to favor the access to polysaccharides by plant polysaccharides degrading proteins, function that could be useful for the design of biotechnological applications.
Project description:Caldicellulosiruptor bescii is an anaerobic hyper thermophile that can utilize a wide range of substrates. However, inhibitors released from biomass can result in unfavorable growth conditions and limit bioconversion to products. Medium as well as intracellular pH are conditions critical for growth and prone to change in effect of fermentation end or by products such as, CO2, organic acids etc. Growth pH for C. bescii as currently reported is a narrow range of 6.8-7.3. In this study, we examined the physiological and systems level responses of C. bescii to growth at acidic pH. Samples collected from bottles, controlled batch, fed-batch and chemostat systems were subjected to growth, product and integrated omics profiling. It was discovered that in batch reactors, lowering pH from 7.2 to 6.0 at the mid-log phase, led to a significant increase in growth and product yields. Time course transcriptomics data collected from these batch reactors was analyzed to try and get a better understanding of the underlying mechanisms for improved growth.
Project description:The rumen harbors a complex mixture of archaea, bacteria, protozoa and fungi that efficiently breakdown plant biomass and its complex dietary carbohydrates into soluble sugars that can be fermented and subsequently converted into metabolites and nutrients utilized by the host animal. While rumen bacteria populations have been well documented, only a fraction of the rumen eukarya are taxonomically and functionally characterized, despite the recognition that they contribute to the cellulolytic phenotype of the rumen fauna. To investigate how anaerobic fungi actively engage in digestion of recalcitrant fiber that is resistant to the initial stages of rumination, we resolved genome-centric metaproteome and metatranscriptome datasets generated from switchgrass samples incubated in nylon bags within the rumen of cannulated dairy cows for 48 hours.
Project description:Producing the fuels and chemicals from renewable plant biomass has been thought as a feasible way for global sustainable development. However, the economical efficiency of biorefinery remains challenges. Here a cellulolytic thermophilic fungus, Myceliophthora thermophila, was constructed into a platform through metabolic engineering, which can efficiently convert lignocellulose to important bulk chemicals for polymers, four carbon 1, 4-diacids (malic and succinic acid), directly from lignocellulose without any extra enzymes addition or complicated pretreatment, with titer of over 200 g/L on cellulose and 110 g/L on plant biomass (corncob) during fed-batch fermentation. Our study represents a milestone of consolidated bioprocessing technology (CBP) and offers a new promising system for cost-effectively production of biomass-based chemicals and potentially fuels.
Project description:In this study we examined an anaerobic digester reactor fed with cellulose in order to identify cellulose degrading microorganisms using a culture independent approach. A metagenome was linked to the newly synthesized proteins involved by cellulose, by investigation of labelled proteins (Protein-SIP). The study aims at identifying microorganisms involved in the degradation of plant-based biomass.