An economical biorefinery process for propionic acid production from glycerol and potato juice using high cell density fermentation.

An economically sustainable process was developed for propionic acid production by fermentation of glycerol using Propionibacterium acidipropionici and potato juice, a by-product of starch processing, as a nitrogen/vitamin source. The fermentation was done as high-cell-density sequential batches with cell recycle. Propionic acid production and glycerol consumption rates were dependent on initial biomass concentration, and reached a maximum of 1.42 and 2.30gL(-1)h(-1), respectively, from 50gL(-1) glycerol at initial cell density of 23.7g(CDW)L(-1). Halving the concentration of nitrogen/vitamin source resulted in reduction of acetic and succinic acids yields by ∼39% each. At glycerol concentrations of 85 and 120gL(-1), respectively, 43.8 and 50.8gL(-1) propionic acid were obtained at a rate of 0.88 and 0.29gL(-1)h(-1) and yield of 84 and 78mol%. Succinic acid was 13g% of propionic acid and could represent a potential co-product covering the cost of nitrogen/vitamin source

Biotransformation of glycerol to 3-hydroxypropionaldehyde: Improved production by in situ complexation with bisulfite in a fed-batch mode and separation on anion exchanger.

3-Hydroxypropionaldehyde (3HPA) is an important C3 chemical that can be produced from renewable glycerol by resting whole cells of Lactobacillus reuteri. However the process efficiency is limited due to substrate inhibition, product-mediated loss of enzyme activity and cell viability, and also formation of by-products. Complex formation of 3HPA with sodium bisulfite and subsequent binding to Amberlite IRA-400 was investigated as a means of in situ product recovery and for overcoming inhibition. The adsorption capacity and -isotherm of the resin were evaluated using the Langmuir model. The resin exhibited maximum capacity of 2.92mmol complex/g when equilibrated with 45mL solution containing an equilibrium mixture of 2.74mmol 3HPA-bisulfite complex and 2.01mmol free 3HPA. The dynamic binding capacity based on the breakthrough curve of 3HPA and its complex on passing a solution with 2.49mmol complex and 1.65mmol free 3HPA was 2.01mmol/g resin. The bound 3HPA was desorbed from the resin using 0.20M NaCl with a high purity as a mixture of complexed- and free 3HPA at a ratio of 0.77mol/mol. Fed-batch biotransformation of glycerol (818.85mmol) with in situ 3HPA complexation and separation on the bisulfite-functionalized resin resulted in an improved process with consumption of 481.36mmol glycerol yielding 325.54mmol 3HPA at a rate of 17.13mmol/h and a yield of 68 mol%. Also, the cell activity was maintained for at least 28h

Production of glycidyl ethers by chemo-enzymatic epoxidation of allyl ethers

Production of glycidyl ethers is industrially carried Out by reacting alcohols with epichlorhydrin, a potentially carcinogenic compound. This paper investigates a less hazardous alternative-that of a chemo-enzymatic process in which Candida antarctica lipase B catalysed generation of peracid from a carboxylic acid is followed by a Prileshajev epoxidation of the corresponding allyl ether. Trimethylolpropane monoallyl ether (TMPME) was used as a model substrate. A maximal epoxide product yield of 77% was achieved through the optimization of temperature. acid concentration and hydrogen peroxide concentration. Peracid formation was considerably faster than the subsequent epoxidation step, and accumulation of the peracid was Found to be important to drive the epoxidation forward. (C) 2008 Elsevier B.V. All rights reserved

Bioremediation of industrial dyes: black reactive 5 and methylene blue by white rot fungus

The aim of the presence research work is to discover the degree of dye decolourization by novel white rot fungi isolated from soil at three different sites; agriculture, virgin forest soil and composting in Johore. Initial experiment was performed with 29 white rot fungus isolates and 3 standard strains, namely Phanerochaete chrysosporium (DSM 6909), Bkerjandera adusta (DSM 4710) and Phlebia radiata (DSM 2111). Soil characteristics; pH, moisture, total viable count, total fungi as well as fungal cell morphology were performed during analysis. White rot fungi were isolated and cultivated on solid medium containing indicator compounds that enabled the detection of enzymes peroxidase as specific colour reactions using guaicol. Selected isolates then were performed in solid medium containing 0.2% dyes (Methylene blue and Reactive Black 5) and incubated up to 10 days at 30 °C before the decolourization rate was observed. The screening work resulted in isolation of 26 positive fungal strains. Liquid cultivations of positive strains confirmed that 24 out of 26 dye degrader were found in the screening. Methylene blue was found to be the most decolorized by white rot fungi with 68.52±3.88% compared to Reactive Black 5, 59.91±3.42 %, respectively. There was significance difference in decolorizing for both dyes responded by soil isolates from different locations. But, in comparison among standard strains, non-significance was observed. P. chrysosporium present the best degrader among the other standard strains for both dyes. Analysis of variance for different locations showed that isolates from virgin forest soil was found to be the most significance in decolourization of methylene blue while composting site for decolourization of Reactive Black 5 dye. This study also suggests that plate-test screening based on polymeric dye compound; guaiacol is an efficient way to screening novel white rot fungus. Further identification and ability to degrade various biological products such as lignin and halo-cellulose should be done as essential to find local and efficient white rot fungus to further develop these industrial applications

Flux analysis of the Lactobacillus reuteri propanediol-utilization pathway for production of 3-hydroxypropionaldehyde, 3-hydroxypropionic acid and 1,3-propanediol from glycerol

Background Lactobacillus reuteri converts glycerol to 3-hydroxypropionic acid (3HP) and 1,3-propanediol (1,3PDO) via 3-hydroxypropionaldehyde (3HPA) as an intermediate using enzymes encoded in its propanediol-utilization (pdu) operon. Since 3HP, 1,3PDO and 3HPA are important building blocks for the bio-based chemical industry, L. reuteri can be an attractive candidate for their production. However, little is known about the kinetics of glycerol utilization in the Pdu pathway in L. reuteri. In this study, the metabolic fluxes through the Pdu pathway were determined as a first step towards optimizing the production of 3HPA, and co-production of 3HP and 1,3PDO from glycerol. Resting cells of wild-type (DSM 20016) and recombinant (RPRB3007, with overexpressed pdu operon) strains were used as biocatalysts. Results The conversion rate of glycerol to 3HPA by the resting cells of L. reuteri was evaluated by in situ complexation of the aldehyde with carbohydrazide to avoid the aldehyde-mediated inactivation of glycerol dehydratase. Under operational conditions, the specific 3HPA production rate of the RPRB3007 strain was 1.9 times higher than that of the wild-type strain (1718.2 versus 889.0 mg/gCDW.h, respectively). Flux analysis of glycerol conversion to 1,3PDO and 3HP in the cells using multi-step variable-volume fed-batch operation showed that the maximum specific production rates of 3HP and 1,3PDO were 110.8 and 93.7 mg/gCDW.h, respectively, for the wild-type strain, and 179.2 and 151.4 mg/gCDW.h, respectively, for the RPRB3007 strain. The cumulative molar yield of the two compounds was ~1 mol/mol glycerol and their molar ratio was ~1 mol3HP/mol1,3PDO. A balance of redox equivalents between the glycerol oxidative and reductive pathway branches led to equimolar amounts of the two products. Conclusions Metabolic flux analysis was a useful approach for finding conditions for maximal conversion of glycerol to 3HPA, 3HP and 1,3PDO. Improved specific production rates were obtained with resting cells of the engineered RPRB3007 strain, highlighting the potential of metabolic engineering to render an industrially sound strain. This is the first report on the production of 3HP and 1,3PDO as sole products using the wild-type or mutant L. reuteri strains, and has laid ground for further work on improving the productivity of the biotransformation process using resting cells

Improved propionic acid production from glycerol: combining cyclic batch-and sequential batch fermentations with optimal nutrient composition

Propionic acid was produced from glycerol using Propionibacterium acidipropionici. In this study, the impact of the concentrations of carbon and nitrogen sources, and of different modes of high cell density fermentations on process kinetics and -efficiency was investigated. Three-way ANOVA analysis and batch cultivations at varying C/N ratios at pH 6.5 revealed that propionic acid production rate is significantly influenced by yeast extract concentration. Glycerol to yeast extract ratio (w w−1) of 3:1 was required for complete glycerol consumption, while maintaining the volumetric productivity. Using this optimum C/N ratio for propionic acid production in cyclic batch fermentation gave propionate yield up to 93 mol% and productivity of 0.53 g L−1 h−1. Moreover, sequential batch fermentation with cell recycling resulted in production rates exceeding 1 g L−1 h−1 at initial glycerol up to 120 g L−1, and a maximum of 1.63 g L−1 h−1 from 90 g L−1 glycerol