Cultivation engineering of microbial bioplastics production

Abstract Theoretical yields of poly- d (−)-3-hydroxybutyrate (PHB) from several carbon sources have been estimated from biochemical pathways leading to PHB. In estimating the yields, a special emphasis is made on recycling (or regeneration) of NADP⁺ which is the co-substrate of acetoacetyl-CoA reductase, one of three key enzymes involved in the biosynthesis of PHB. As a NADP⁺-regenerating enzyme, glucose-6-phosphate dehydrogenase or isocitrate dehydrogenase is conceived. Theoretical and observed yields have been compared when polyhydroxyalkanoates (PHA) were synthesized from methanol and from n -amyl alcohol by a methylotroph, Paracoccus denitrificans .
An equation, which predicts the overall yield of PHB when allowance is made for non-PHB biomass formation in actual bacterial PHB production, has been derived as a function of both theoretical yields and PHB content of the total dry cell mass. The ratio of the overall (yield) to be theoretical yield is roughly proportional to the PHB content. A novel specific PHB formation rate on the basis of the residual biomass (total biomass-PHB contained) was proposed. The specific PHB formation rate decreased according to a mono-molecular decay model whose decay constant depended solely on the C/N ratio of the feed solution. From this model, an equation has been derived to calculate the volumetric productivity of PHB on the assumption that the total amount of the residual biomass is unchanged in the nitrogen-deficient PHB formation phase. Also, a graphical procedure has been shown to calculate the volumetric productivity of PHB. A comparison has been made between several data of PHB productivities that have been calculated from the literature.     

Oxidation of dimethyl sulfide by various aromatic compound oxygenases from bacteria

As a result of the determination of dimethyl sulfide (DMS) oxidizing activity of bacterial aromatic compound oxygenases, multicomponent monooxygenases (DmpKLMNOP from Pseudomonas sp. CF600, AphKLMNOP from Comamonas testosteroni TA441, and TodABCDEF from Pseudomonas sp. JS150), single component monooxygenases (TfdB from Pseudomonas putida EST4011 and XylMA from Pseudomonas putida mt-2), and dioxygenases (CumA1A2A3A4 from Pseudomonas fluorescens IP01 and PahAaAbAcAd from Pseudomonas putida OUS82) showed DMS-oxidizing activity, while CarAaAcAd from Pseudomonas sp. CA10 and SoxC from Rhodococcus sp. IGTS8 did not. These results indicate the possibilities that these oxygenases might oxidize DMS to DMSO under the natural condition in the environment.Present address: Laboratory of Microbiology, The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan     

Jumbled spine and ribs (Jsr): a new mutation on mouse Chromosome 5

Jumbled spine and ribs (Jsr) is an autosomal dominant mutation that results in malformation of the axial skeleton. The vertebrae of mutant mice (Jsr/+) are all shorter than those of normal mice (+/+) in the inbred line and show various abnormalities. In addition, several ribs are fused at their proximal region because of fusion of thoracic vertebrae. In this study, we localized the Jsr mutation on distal Chromosome (Chr) 5 and constructed a high-resolution map. Chromosomal mapping was performed with an inter-subspecific backcross of (CKH-Jsr/+× MOG) F₁ carrying the Jsr allele and CKH-+/+. The predicted gene order around Jsr was determined to be cen–(Epo, Pdgfa, D5Mit31, D5Mit374)–(Jsr, Nfe2u, D5Mit99, D5Mit247, D5Mit284, D5Mit292, D5Mit327)–D5Mit328–tel. Subsequently, high-resolution mapping concluded the Jsr localization to be cen–Nfe2u–1.0cM–Jsr–0.2cM–D5Mit247,292–tel. Jsr/Jsr homozygotes are alive, as the mutation is not lethal. Based on histological analysis of mutant embryos, Jsr is hypothesized to be caused by abnormal development of primordial cells in the axial skeleton. Received: 1 June 1998 / Accepted: 15 October 1998     

Leaf litter thickness,but not plant species,can affect root detection by ground penetrating radar

Aim

Ground penetrating radar (GPR), a nondestructive tool that can detect coarse tree roots, has not yet become a mature technology for use in forests. In this study, we asked two questions concerning this technology: (i) Does the leaf litter layer influence root detection and major indices based on the time interval between zero crossings (T) and the amplitude area (A)? (ii) Can GPR images discriminate roots of different plant species?

Methods

Roots buried in a sandy bed, which was covered with different thicknesses of leaf litter, were scanned using a 900 MHz GPR antenna. Roots of four plant species in the bed were also scanned.

Results

Leaf litter decreased root reflections without distorting the shape of the hyperbolas in the radar profile. A values decreased with increasing litter thickness, whereas T was independent of litter thickness. For all species combined, GPR indices were significantly correlated with root diameter.

Conclusions

Leaf litter dramatically decreased root detection, but the influence of the litter could be ignored when the sum of T for all reflection waveforms (ΣT) is adopted to estimate root diameter. To use A values to detect roots, litter should be removed or equalized in thickness. Radar profiles could not reliably differentiate among roots belonging to plants of different species.

     

Cloning of Thermostable α-Amylase Gene Using Bacillus subtilis Phage ρ11 as a Vector

Using a method consisting of two repetitions of “prophage transformation,” the thermostable α-amylase gene in Bacillus subtilis has been cloned in temperate phage ρ11.     

Computational analysis and functional expression of ancestral copepod luciferase

We recently reported the cDNA sequences of 11 copepod luciferases from the superfamily Augaptiloidea in the order Calanoida. They were classified into two groups, Metridinidae and Heterorhabdidae/Lucicutiidae families, by phylogenetic analyses. To elucidate the evolutionary processes, we have now further isolated 12 copepod luciferases from Augaptiloidea species (Metridia asymmetrica, Metridia curticauda, Pleuromamma scutullata, Pleuromamma xiphias, Lucicutia ovaliformis and Heterorhabdus tanneri). Codon-based synonymous/nonsynonymous tests of positive selection for 25 identified copepod luciferases suggested that positive Darwinian selection operated in the evolution of Heterorhabdidae luciferases, whereas two types of Metridinidae luciferases had diversified via neutral mechanism. By in silico analysis of the decoded amino acid sequences of 25 copepod luciferases, we inferred two protein sequences as ancestral copepod luciferases. They were expressed in HEK293 cells where they exhibited notable luciferase activity both in intracellular lysates and cultured media, indicating that the luciferase activity was established before evolutionary diversification of these copepod species.