Production Of Value-added Bioproducts Research Articles

Co-upgrading of ethanol-assisted depolymerized lignin: A new biological lignin valorization approach for the production of protocatechuic acid and polyhydroxyalkanoic acid

This study presents a promising biological co-upgrading of ethanol-assisted depolymerized lignin (EDL) into protocatechuic acid (PCA) and polyhydroxyalkanoic acid (PHA) without any separation process. A depolymerized alkali lignin containing various G-lignin-type monomers at a concentration of 77 mg/mL was used for co-upgrading. An engineered Pseudomonas putida KT2440 strain was constructed by knocking out the protocatechuate 3, 4-dioxygenase, expression of the formaldehyde utilization pathway, and the expression of aldehyde dehydrogenase to enhance the efficiency of the ethanol utilization pathway. The growth and production of value-added bioproducts have been promoted by the utilization of formaldehyde, resulted in 6.73 ± 0.26 mg/L of PCA with a 17.5% (w/w) yield of total lignin monomers, and 303.66 ± 26.75 mg/L of PHA with 21.26% (w/w) of dry cell weight from 0.5 mL EDL. Moreover, the ethanol solvent used for lignin depolymerization was also utilized along with depolymerized lignin for co-upgrading to value-added products.

Production of Value-Added Bioproducts Using a Modified Continuous Biofilm Reactor by Citrobacter Freundii DSM 15979

The present paper reports the results of Citrobacter freundii, strain DSM 15979, that was tested for its ability to produce value added chemicals from biodiesel derived glycerol in a mesophilic fluidized bed biofilm reactor operating under continuous conditions at a specified hydraulic retention time (HRT) at 30°C. Elevating feed concentrations (10 to 144 g/L) were tested in order to understand their effects on simultaneous production of value added products with immobilized whole cells. Gin was found to be a significant independent variable for the productions of 1,3-PDO, 2,3-BD, ethanol, acetic, succinic and lactic acids under different organic loading rates (OLR). The major metabolite in the metabolic pathway was found to be 1,3-PDO followed by 2,3-BD reaching the maximum values as 26.1 and 18.8 g/L under the conditions of 92 g/L crude glycerol and 8 h, which is represents an OLR of 11.5 g/L.h, suggesting the formation of biofilms favor the utilization of high substrate concentration to enhance the mixed fermentation.

Complete Utilization of the Major Carbon Sources Present in Sugar Beet Pulp Hydrolysates by the Oleaginous Red Yeasts Rhodotorula toruloides and R. mucilaginosa.

Agro-industrial residues are low-cost carbon sources (C-sources) for microbial growth and production of value-added bioproducts. Among the agro-industrial residues available, those rich in pectin are generated in high amounts worldwide from the sugar industry or the industrial processing of fruits and vegetables. Sugar beet pulp (SBP) hydrolysates contain predominantly the neutral sugars d-glucose, l-arabinose and d-galactose, and the acidic sugar d-galacturonic acid. Acetic acid is also present at significant concentrations since the d-galacturonic acid residues are acetylated. In this study, we have examined and optimized the performance of a Rhodotorula mucilaginosa strain, isolated from SBP and identified at the molecular level during this work. This study was extended to another oleaginous red yeast species, R. toruloides, envisaging the full utilization of the C-sources from SBP hydrolysate (at pH 5.0). The dual role of acetic acid as a carbon and energy source and as a growth and metabolism inhibitor was examined. Acetic acid prevented the catabolism of d-galacturonic acid and l-arabinose after the complete use of the other C-sources. However, d-glucose and acetic acid were simultaneously and efficiently metabolized, followed by d-galactose. SBP hydrolysate supplementation with amino acids was crucial to allow d-galacturonic acid and l-arabinose catabolism. SBP valorization through the production of lipids and carotenoids by Rhodotorula strains, supported by complete catabolism of the major C-sources present, looks promising for industrial implementation.

Bioconversion of oat hull and miscanthus cellulose to glucose solutions

Cellulose-containing raw materials are currently considered to be among the most promising types of raw materials for the production of value-added bio-products. However, for the implementation of the developed process, the application of universal pre-processing methods is a prerequisite. In the present paper, a study into the bioconversion of oat hull and miscanthus cellulose samples by enzymatic hydrolysis into glucose solutions is presented. The substrates were obtained by two-stage processing of raw materials with dilute solutions of nitric acid and sodium hydroxide. Enzymatic hydrolysis was carried out using the Cellolux-A and Ultraflo Core enzyme preparations at an initial substrate concentration of 40 g/L. At the first stage, the reactivity of the substrates to enzymatic hydrolysis in an acetate buffer solution was studied over a period of 72 hours. Cellulose samples from both types of raw materials were established to possess equally high reactivity in terms of the reducing substances. Glucose obtained from the substrate yielded 94–95 % and 88–91 %, respectively. This indicates the universality of the pre-treatment method used for raw materials having a cellulose content of 35–45 %. At the second stage, hydrolysis of the substrates was carried out using a pilot fermenter in an aqueous medium with an excess of enzyme preparations. Over a period of 32 hours, aqueous hydrolysates were obtained with a concentration of reducing substances and glucose equal to 42 g/L (94 % yield from the substrate) and 33–35 g/L (74–78 % yield from the substrate), respectively. The glucose (79–83 %) and pentose (1–2 %) content of the reducing substances indicates glucose to predominate in the composition of the resulting solutions. The high bioconversion efficiency rate is additionally demonstrated by a comparative analysis of scanning electron spectroscopy results for substrates and residues following hydrolysis in a pilot fermenter. Glucose solutions obtained in an aqueous medium are emerging as promising materials for the preparation of culture media and the synthesis of valuable metabolites. The authors declare no conflict of interests regarding the publication of this article.

Partial purification and characterization of a trypsin inhibitor isolated from Adenanthera pavonina L. seeds

Trypsin inhibitors are important tools used by plants against parasites and once isolated may be directed to biotechnological applications. In this work, a trypsin inhibitor was extracted and isolated from the seeds of Adenanthera pavonina L. (Fabaceae). After, the biomolecule was purified and characterized in terms of its thermal stability and molecular weight. In addition its toxic effect against Artemia salina was investigated. The purification process was based in cetonic precipitation with acetone 70% (v/v) and anion-exchange chromatography on DEAE-Sephadex G-50. SDS–PAGE analysis, under reducing condition, showed that protein consists of a single polypeptide chain with molecular mass of approximately 14.1kDa. The biomolecule is a competitive inhibitor with an inhibition stoichiometry of 1:2 for bovine trypsin. The inhibitor purified presented thermal stability in wide range of temperature (25–100°C), and showed still effective inhibition (61%) until 100°C during 30min. Furthermore a volume of 0.16mg/mL of the inhibitor was enough to present toxicity against the larvae of Artermia salina (100% of death rate after 72h). The species A. pavonina is therefore source of trypsin inhibitors with high activity and could be used for obtaining the biomolecule in accord to its demand mostly in pharmaceutical and environment industry, medicine and others. As a likely source of potent trypsin inhibitors, the extract obtained from seeds of A. pavonina is discussed to be useful directly in the agro-industry, in the production of value-added bioproducts or in general biotechnological applications.