Construction of a simple biocatalyst using psychrophilic bacterial cells and its application for efficient 3-hydroxypropionaldehyde production from glycerol

Most whole cell biocatalysts have some problems with yields and productivities because of various metabolites produced as byproducts and limitations of substrate uptake. We propose a psychrophile-based simple biocatalyst for efficient bio-production using mesophilic enzymes expressed in psychrophilic Shewanella livingstonensis Ac10 cells whose basic metabolism was inactivated by heat treatment. The 45°C heat-treated cells expressing lacZ showed maximum beta-galactosidase activity as well as chloroform/SDS-treated cells to increase membrane permeability. The fluorescent dye 5-cyano-2,3-ditolyl-tetrazolium chloride staining indicated that most basic metabolism of Ac10 was lost by heat treatment at 45˚C for 10 min. The simple biocatalyst was applied for 3-HPA production by using Klebsiella pneumoniae dhaB genes. 3-HPA was stoichiometrically produced with the complete consumption of glycerol at a high production rate of 8.85 mmol 3-HPA/g dry cell/h. The amount of 3-HPA production increased by increasing the concentrations of biocatalyst and glycerol. Furthermore, it could convert biodiesel-derived crude glycerol to 3-HPA.We thank Professor Tatsuo Kurihara in Kyoto University for providing S. livingstonenesis Ac10-Rifr

Complete genome sequence of Nitratireductor sp. strain OM-1:A lipid-producing bacterium with potential use in wastewater treatment

Reducing CO 2 emissions is necessary to alleviate rising global temperature. Renewable sources of energy are becoming an increasingly important substitute for fossil fuels. An important step in this direction is the isolation of novel, technologically relevant microorganisms. Nitratireductor sp. strain OM-1 can convert volatile short-chain fatty acids in wastewater into 2-butenoic acid and its ester and can accumulate intracellularly esterified compounds up to 50% of its dried cell weight under nitrogen- depleted conditions. It is believed that a novel fatty acid biosynthesis pathway including an esterifying enzyme is encoded in its genome. In this study, we report the whole-genome sequence (4.8 Mb) of OM-1, which comprises a chromosome (3,977,827 bp) and a megaplasmid (857,937 bp). This sequence information provides insight into the genome organization and biochemical pathways of OM-1. In addition, we identified lipid biosynthesis pathways in OM-1, paving the way to a better understanding of its biochemical characterization

Hydrogen and methane fermentation of solid wastes from food industry

To treat and recover energy from food industrial solid wastes, methane fermantion is very altractive, in this article, therefore, researches on methane fermentation of solid wastes from a Japanese Sake brewery, bread manufacture and soy sauce brewery were reviewed. To solubilize and acidify the waste from a Japanese Sake brewery, hyperthemophilic archaeon Pyrococcus furiosus could be applied. A perfusion culture developed to increase cell concentration gave 0.4 g/l/h of acetate production rate from rice powder. Futhermore, a continuous culture using the cells fixed on a porous ceramic carrier gave 0.14 g/l/h of acetate rate at the dilution rate of 0.4 h-1. By using a microbial consortium, when 100 g-wet wt./l of the bread waste was fermented under controlled pH7 conditions, 91(null)S was reduced after 24h and 240 mM H2 was produced. When the diluted culture broth after the hydrogen fermentation was supplied continuously into a UASB methanogenic reactor, the optimum loading of 9.5 g-TOC/l/day gave 80% TOC removal, 408 mmol/l/day of methane production rate and ca. 0.6 methane yield as carbon base. To reduce MLSS in soy source refuse (SSR) and produce methane successfully, thermophilic methanogenic suldge obtained from a municipal wastewater treatment plant could be used as seed. At 25 g-wet wt./l of SSR, 120 mM CH4 production and 50% (w/v) MLSS reduction were observed after 35 d. Acclimatization of the sludge to the waste was effective to increase the methane production rate in the pH-controlled fed-batch culture using the stirred tank reactor. Development of high rate production of hydrogen-methane in two-stage process was also discussed

Removal of Acetic Acid from Bacterial Culture Media by Adsorption onto a Two-Component Composite Polymer Gel

Organic acids, including acetic acid, are the metabolic products of many microorganisms. Acetic acid is a target product useful in the fermentation process. However, acetic acid has an inhibitory effect on microorganisms and limits fermentation. Thus, it would be beneficial to recover the acid from the culture medium. However, conventional recovery processes are expensive and environmentally unfriendly. Here, we report the use of a two-component hydrogel to adsorb dissociated and undissociated acetic acid from the culture medium. The Langmuir model revealed the maximum adsorption amount to be 44.8 mg acetic acid/g of dry gel at neutral pH value. The adsorption capacity was similar to that of an ion-exchange resin. In addition, the hydrogel maintained its adsorption capability in a culture medium comprising complex components, whereas the ion-exchange did not adsorb in this medium. The adsorbed acetic acid was readily desorbed using a solution containing a high salt concentration. Thus, the recovered acetic acid can be utilized for subsequent processes, and the gel-treated fermentation broth can be reused for the next round of fermentation. Use of this hydrogel may prove to be a more sustainable downstream process to recover biosynthesized acetic acid

バイオマスを原料とするハイブリッド型フューエルセルシステムの開発

研究期間:平成12-14年度 ; 研究種目:基盤研究B2 ; 課題番号:12555230原著には既発表論文の別刷を含む

Degradation of Glyoxylate and Glycolate with ATP Synthesis by a Thermophilic Anaerobic Bacterium, Moorella sp. Strain HUC22-1▿

The thermophilic homoacetogenic bacterium Moorella sp. strain HUC22-1 ferments glyoxylate to acetate roughly according to the reaction 2 glyoxylate → acetate + 2 CO2. A batch culture with glyoxylate and yeast extract yielded 11.7 g per mol of cells per substrate, which was much higher than that obtained with H2 plus CO2. Crude extracts of glyoxylate-grown cells catalyzed the ADP- and NADP-dependent condensation of glyoxylate and acetyl coenzyme A (acetyl-CoA) to pyruvate and CO2 and converted pyruvate to acetyl-CoA and CO2, which are the key reactions of the malyl-CoA pathway. ATP generation was also detected during the key enzyme reactions of this pathway. Furthermore, this bacterium consumed l-malate, an intermediate in the malyl-CoA pathway, and produced acetate. These findings suggest that Moorella sp. strain HUC22-1 can generate ATP by substrate-level phosphorylation during glyoxylate catabolism through the malyl-CoA pathway