Takamasa Kubo

Purification and properties of a chitosanase from Pseudomonas sp. H-14

Purification and Properties of a Chitosanase from Pseudomonas sp. H-14 Kazutoshi Yoshihara, Jun Hosokawa, Takamasa Kubo, Masashi Nishiyama & Yojiro Koba To cite this article: Kazutoshi Yoshihara, Jun Hosokawa, Takamasa Kubo, Masashi Nishiyama & Yojiro Koba (1992) Purification and Properties of a Chitosanase from Pseudomonas sp. H-14, Bioscience, Biotechnology, and Biochemistry, 56:6, 972-973, DOI: 10.1271/bbb.56.972 To link to this article: http://dx.doi.org/10.1271/bbb.56.972

Chemi-Thermomechanical Pulping of Para Rubber Waste Wood

Chemi-thermomechanical pulping process (CTMP process) of Para rubber wood was investigated by using a laboratorial single disc pressurized refiner with the intension of clarifying the effect of Na2SO3 and alkaline Na2SO3 pre-treatment on sheet properties. The Na2SO3 pre-treatment produced little effect on fiber length distribution and demanded high energy requirement in refining. The combination treatment with NaOH and Na2SO3 had a synergistic effect to give great enhancement of sheet properties and sharp reduction of energy consumption. The pre-treatment also reduced latex content represented by alcohol-benzene extractive. By CTMP process with alkaline Na2SO3 pre-treatment, the Para rubber wood provided the pulp with properties almost equivalent to those of TMPs produced from soft woods. The demerit of lowering of brightness caused by alkaline treatment was recovered by brightening using 3% H2O2.

New application of cellulose and chitosan for biodegradable polymer material

We found that a combination of fine cellulose and chitosan was suitable for forming biodegradable films and moldings. The composite film demonstrated high strength and had a maximum wet strength at 10-20% chitosan content. Besides the major hydrogen bonding between chitosan and cellulose, the amino groups in chitosan and the trace amounts of carbonyl groups in cellulose played an important role in the formation of the composite. This film was completely decomposed by microorganisms in soil or sea water. The biodegradability was controlled by adjusting the temperature in heat treatment, the quantity of carbonyl group in the cellulose, etc. We have also been working on joint research with companies to produce films, nonwoven fabrics and foams. Foams and nonwoven fabrics of the composite were found to be effective in healing of skin defects of rats. We are also trying to produce fine cellulose material for the biodegradable plastic by simple and convenient method grinding together with an organic solvent. The production of chitosan by cultivation of a fungus such as Rhizopus acetoinus is also discussed.

Biodegradable plastics derived from micro-fibrillated cellulose fiber and chitosan

We have been carrying out studies to develop biodegradable plastics from natural polysaccharides. We have found that a combination of micro-fibrillated cellulose fiber and chitosan produces a useful material that can be used to form biodegradable film and moldings. Cellulose-chitosan composite film demonstrate higher strength than general purpose plastic films, and wet strength peaks when chitosan content is 10-20%. The relatively small amount of chitosan needed is economically convenient because chitosan is more expensive than cellulose. This film biodegrade well in soil, completely dissolving and disappearing in two months. Biodegradability is influenced by the temperature used in thermal treatment the film, the quantity of acid groups in the cellulose, and other factors. These characteristics will be used to control decomposition. Since cellulose-chitosan plastics are not thermoplastics, we have been working on joint research with companies to produce films, nonwoven fabrics and foams. We discuss here the properties and application of these composite moldings.

Studies on Pulping with the Addition of the Reducing Agents (I)

The kraft pulp cooking with the addition of hydrazine as the reducing agent has been studied. The yield of pulp (I) by the addition of hydrazine was 10% more than the normal kraft pulp (II), its color was more light and glossy, and its cooking degree was the same as that of pulp (II). The analytical results of pulp showed that the relative viscosity of pulp (I) was much higher than that of pulp (II), and that chlorine number and pentosan contents were little different in both pulps (I) and (II). The pulp handsheets were prepared and tested on burst factor, breaking length, tear factor and brightness.