Oxidation of dimethyl sulfide byPseudomonas acidovorans DMR-11 isolated from peat biofilter

Summary Pseudomonas acidovorans DMR-11, capable of oxidizing dimethyl sulfide (DMS), was isolated from peat biofilter. DMS as a sole carbon or energy source was not degraded, but it was co-degraded in the medium containing organic carbon sources. The removal rate of DMS in heat-treated glucose medium was 1.12×10^–17 mole/h cell at 30 °C. Dimethyl sulfoxide (DMSO) was the only product of DMS oxidation and was formed stoichiometrically. DMS was reversibly evolved in excess of DMSO. The cell free extract of strain DMR-11 oxidized DMS in presence of NADPH.     

Kinetics of product inhibition in alcohol fermentation-temperature effect in the “sake” brewing

One of the kinteic equations derived previously from a series of sophisticated batch and continuous alcohol fermentations by using a respiration-deficient mutant of baker's yeast is as follows: where dp/dt = ethanol production rate, v0 = specific rate of ethanol production at p = 0, k₂ = empirical constant, K′_s = saturation constant, S = glucose concentration, and X = cell mass concentration. The above equation was confirmed in the previous paper to fit, the brewing of “sake.” The temperature of the specific brewing is not always constant (10 to 18°C). The effect of temperature on v0 was assessed from the Arrhenius plot, assuming that k₂ was independent of temperature. Values of dp/dt taken from the “sake” brewing data were rearranged, taking the temperature change into account. These datu, corrected for the temperature, were found to follow quite favorably the kinetic equation mentioned above. So far, a prediction of the ethanol production rate in practice was rectified to the extent of p = 19%.     

Altered metabolism of bile acids in cholestasis: Determination of 1β- and 6α-hydroxylated metabolites

Trihydroxy and tetrahydroxy bile acid metabolites substituted at the C-1 or C-6 position were studied using the urine, serum and liver tissue from sixteen patients with cholestatic liver diseases. Following extraction, isolation and hydrolysis, bile acids were converted into the dimethylethylsilyl derivatives and assayed by capillary gas chromatography—mass spectrometry. Five 1β-hydroxylated bile acids, viz. 1β,3α,12α-trihydroxy-, 1β,3α,7β-trihydroxy-1, 1β,3α,7α,12α-tetrahydroxy-5β-cholanoic acids and an epimer of the first compound, and two 6α-hydroxylated bile acids, viz. 3α,6α,7α-trihydroxy-, 3α,6α,7α,12α-tetrahydroxy-5β-cholanoic acids, were completely or partially identified. Large amounts of 1β-hydroxylated and 6α-hydroxylated bile acids were found in the urine, whereas only trace amounts were detected in the serum and liver tissue. These findings indicate that altered metabolism, such as 1β- or 6α-hydroxylation of bile acids, is enhanced in cholestasis, and that the resulting hydroxylated metabolites are eliminated in the urine.     

Transformation ofBacillus subtilis with the treatment by alkali cations

Summary ExposingBacillus subtilis cultures to high concentrations of alkali cations, especially K⁺, allows efficient transformation by plasmids. The method allows transformation with unfractionated plasmid DNA, monomeric plasmid DNA as well as linear plasmid DNA.B. subtilis strains, not amenable to natural transformation, were also transformed by the present method.     

Isolation of a gene essential for biosynthesis of the lipopeptide antibiotics plipastatin B1 and surfactin in Bacillus subtilis YB8

Bacillus subtilis YB8 was found to produce the lipopeptide antibiotics surfactin and plipastatin B1. A gene, lpa-8, required for the production of both lipopeptides was cloned from strain YB8. When this gene was inactivated in strain YB8, neither surfactin nor plipastatin B1 was produced. However, the defective strain transformed with an intact lpa-8 gene had restored ability to produce both peptides. Nucleotide sequence analysis of the region essential for the production of the peptides revealed the presence of a large open reading frame. The deduced amino acid sequence of lpa-8 (224 amino acid residues) showed sequence similarity to that of sfp (from surfactin-producing B. subtilis), lpa-14 (from iturin A- and surfactin-producing B. subtilis), psf-1 (from surfactin-producing Bacillus pumilus), gsp (from gramicidin-S-producing Bacillus brevis), and entD (from siderophore-enterobactin-producing Escherichia coli), which are able to complement a defect in the sfp gene and promote production of the lipopeptide antibiotic surfactin. The sequence similarity among these proteins and the product similarity of cyclic peptides suggests that they might be involved in the biosynthesis or secretion of the peptides. Received: 14 July 1995 / Accepted: 22 December 1995     

A rapid and simple method for plasmid copy number comparison

Summary A rapid, simple, and sensitive method for plasmid copy number comparison was developed. The extracted plasmids from the same amount of cells were subjected to agarose gel electrophoresis and the gels photographed. The photographs were processed by a Macintosh image analyser to enumerate the densities of plasmid bands. As a size reference, λ-DNA digested with a restriction enzyme was used. The densities divided by size of plasmids (base pair) would represent relative values of their copy numbers.     

Chemical synthesis of cellulose and cello-oligomers using a hydrolysis enzyme as a catalyst

Regio- and stereo-selective synthesis of polysaccharides and oligosaccharides has been achieved by using glycosyl fluorides as substrates for cellulases. This methodology has successfully been applied to the first synthesis of cellulose via a non-biosynthetic pathway as well as to a selective preparation of cello-oligosaccharides and unnatural oligosaccharides. Using the enzymatic polymerization, it is possible to control the relative direction (parallel or anti-parallel) of each glucan chain in the synthetic cellulose in vitro. Based on these results, a new concept of ‘allos-selectivity’ in polymer synthesis has been proposed.     

Production of a lipopeptide antibiotic, surfactin, by recombinant Bacillus subtilis in solid state fermentation

Production of a lipopeptide antibiotic, surfactin, in solid state fermentation (SSF) on soybean curd residue, Okara, as a solid substrate was carried out using Bacillus subtilis MI113 with a recombinant plasmid pC112, which contains lpa-14, a gene related to surfactin production cloned at our laboratory from a wild-type surfactin producer, B. subtilis RB14. The optimal moisture content and temperature for the production of surfactin were 82% and 37 degrees C, respectively. The amount of surfactin produced by MI113 (pC112) was as high as 2.0 g/kg wet weight, which was eight times as high as that of the original B. subtilis RB14 at the optimal temperature for surfactin production, 30 degrees C. Although the stability of the plasmid showed a similar pattern in both SSF and submerged fermentation (SMF), production of surfactin in SSF was 4-5 times more efficient than in SMF. (c) 1995 John Wiley & Sons, Inc.     

Production of bacterial cellulose by Acetobacter xylinumwith an air-lift reactor

Bacterial cellulose was produced by Acetobacter xylinum subsp. surcrofermentans BPR2001 in a 50 liter air-lift reactor using fructose as the main carbon source. When air was supplied, the production of the cellulose was only 2.3 g/l in 80 h but when O -fortified air was supplied, the cellulose concentration increased to 5.63 g/l in 28 h and the productivity of the cellulose in an air-lift reactor with O -fortified air supply was comparable to that in a mechanically agitated jar fermenter.     

Preferential utilization of phenol rather than glucose by Trichosporon cutaneum possessing a partially constitutive catechol 1,2-oxygenase.

A phenol-utilizing yeast, Trichosporon cutaneum POB 14, which has a partially constitutive activity of catechol 1,2-oxygenase, utilized phenol in preference to glucose in a medium containing both phenol (200 mg/liter) and glucose (0.15%) as carbon sources. The glucose consumption was not observed until the concentration of phenol decreased to around 10 mg/liter. This phenomenon was confirmed by [U-14C]glucose uptake experiments. The intracellular activities of hexokinase (EC 2.7.1.1) and catechol 1,2-oxygenase (EC 1.13.1.1) changed inversely when phenol was added during growth in the glucose medium.