Microbial removal of nutrients from anaerobic digestate: assessing product-coupled and non-product-coupled approaches.

Although anaerobic digestate contains >90% water, the high nutrient content of digestate makes it economically and technically intractable to treatment by existing wastewater treatment technologies. This study separately assessed the feasibility of nutrient removal from digestate by DSM 905 and a culture of phosphate-accumulating organisms (PAOs). With DSM 905, we investigated concomitant nutrient removal from digestate-supplemented medium and fumaric acid production, as a potentially economical strategy for digestate treatment.

Microbial detoxification of lignocellulosic biomass hydrolysates: Biochemical and molecular aspects, challenges, exploits and future perspectives.

Valorization of lignocellulosic biomass (LB) has the potential to secure sustainable energy production without impacting food insecurity, whist relieving over reliance on finite fossil fuels. Agro-derived lignocellulosic residues such as wheat straw, switchgrass, rice bran, and miscanthus have gained relevance as feedstocks for the production of biofuels and chemicals. However, the microorganisms employed in fermentative conversion of carbohydrates to fuels and chemicals are unable to efficiently utilize the sugars derived from LB due to co-production of lignocellulose-derived microbial inhibitory compounds (LDMICs) during LB pretreatment.

Effects of and Medium Modifications on Acetone-Butanol-Ethanol Production From Switchgrass.

The presence of lignocellulose-derived microbial inhibitory compounds (LDMICs) in lignocellulosic biomass (LB) hydrolysates is a barrier to efficient conversion of LB hydrolysates to fuels and chemicals by fermenting microorganisms. Results from this study provide convincing evidence regarding the effectiveness of metabolically engineered NCIMB 8052 for the fermentation of LB-derived hydrolysates to acetone-butanol-ethanol (ABE). The engineered microbial strain (_SDR) was produced by the integration of an additional copy of a short-chain dehydrogenase/reductase (SDR) gene (3904) into the chromosome of NCIMB 8052 wildtype, where it is controlled by the constitutive thiolase promoter.

Viable strategies for enhancing acetone-butanol-ethanol production from non-detoxified switchgrass hydrolysates.

A process engineering strategy was investigated towards developing a viable scheme for effective conversion of hydrothermolysis pretreated non-detoxified switchgrass hydrolysates (SH) to acetone butanol ethanol (ABE) using a metabolically engineered strain of Clostridium beijerinckii NCIMB 8052, C. beijerinckii_AKR. The engineered strain was modified by homologous integration into the chromosome and constitutive expression of Cbei_3974, which encodes an aldo-keto reductase.

Ribozyme-Mediated Downregulation Uncovers DNA Integrity Scanning Protein A (DisA) as a Solventogenesis Determinant in .

Carbon catabolite repression (CCR) limits microbial utilization of lignocellulose-derived pentoses. To relieve CCR in NCIMB 8052, we sought to downregulate catabolite control protein A (CcpA) using the M1GS ribozyme technology. A CcpA-specific ribozyme was constructed by tethering the catalytic subunit of RNase P (M1 RNA) to a guide sequence (GS) targeting CcpA mRNA (M1GS).

Use of fruit pulp as a substrate for biosurfactant production.

In this study, we explored the possibility of utilizing the succulent pulp of (SM) as feedstock for the synthesis of biosurfactants by spp. The cultures were composed of basic mineral medium amended with SM, SM + glucose, glucose (GLC), and nutrient broth (NB) as carbon sources. Biosurfactant production was determined by surface-active properties such as hemolysis, emulsification index (E), drop collapse, oil-spreading assays, and reduction of surface tension.

Inactivation of the Levansucrase Gene in Paenibacillus polymyxa DSM 365 Diminishes Exopolysaccharide Biosynthesis during 2,3-Butanediol Fermentation.

The formation of exopolysaccharides (EPSs) during 2,3-butanediol (2,3-BD) fermentation by increases medium viscosity, which in turn presents considerable technical and economic challenges to 2,3-BD downstream processing. To eliminate EPS production during 2,3-BD fermentation, we used homologous recombination to disable the EPS biosynthetic pathway in The gene which encodes levansucrase, the major enzyme responsible for EPS biosynthesis in , was successfully disrupted. The levansucrase null mutant produced 2.

Feasibility of using biochar as buffer and mineral nutrients replacement for acetone-butanol-ethanol production from non-detoxified switchgrass hydrolysate.

Biochar can be an inexpensive pH buffer and source of mineral and trace metal nutrients in acetone-butanol-ethanol (ABE) fermentation. This study evaluated the feasibility of replacing expensive 4-morpholineethanesulfonic acid (MES) P2 buffer and mineral nutrients with biochar made from switchgrass (SGBC), forage sorghum (FSBC), redcedar (RCBC) and poultry litter (PLBC) for ABE fermentation. Fermentations using Clostridium beijerinckii ATCC 51743 in glucose and non-detoxified switchgrass hydrolysate media were performed at 35 °C in 250 mL bottles for 72 h.

Chromosomal integration of aldo-keto-reductase and short-chain dehydrogenase/reductase genes in Clostridium beijerinckii NCIMB 8052 enhanced tolerance to lignocellulose-derived microbial inhibitory compounds.

In situ detoxification of lignocellulose-derived microbial inhibitory compounds is an economical strategy for the fermentation of lignocellulose-derived sugars to fuels and chemicals. In this study, we investigated homologous integration and constitutive expression of Cbei_3974 and Cbei_3904, which encode aldo-keto reductase and previously annotated short chain dehydrogenase/reductase, respectively, in Clostridium beijerinckii NCIMB 8052 (Cb), resulting in two strains: Cb_3974 and Cb_3904. Expression of Cbei_3974 led to 2-fold increase in furfural detoxification relative to Cb_3904 and Cb_wild type.

Investigation of relationship between 2,3-butanediol toxicity and production during growth of Paenibacillus polymyxa.

Understanding the capacity of Paenibacillus polymyxa DSM 365 to tolerate increasing concentrations of 2,3-butanediol (2,3-BD) is critical to engineering a 2,3-BD-overproducing strain. Hence, we investigated the response of P. polymyxa to high 2,3-BD concentrations.

Unorthodox methods for enhancing solvent production in solventogenic Clostridium species.

While production of biofuels from renewable resources is currently receiving increased attention globally, concerns on availability and sustainability of cheap substrates for their production are growing as well. Lignocellulose-derived sugars (LDS) remain underutilized and merit consideration as a key feedstock. Among other obstacles such as low yield and low solvent titer, mitigation of stresses stemming from lignocellulose-derived microbial inhibitory compounds (LDMICs) that severely impair cell growth and solvent production is a major area of research interest.