• Microbiology and Biotechnology Letters
• /
• v.17 no.5
• /
• pp.475-480
• /
• 1989

The extracellular polysaccharide was isolated from the culture of Ps. delafieldii and its rheological property was evaluated. The aqueous solution was extremely viscous and shows pseudoplastic behaviour. The flow behaviour index and apparent viscosity of 1 ％solution were 0.09 and 1169 mPa·s. The solution was stable over pH change but did not have thermal stability. The activation energy of flow of 1 ％ solution was 4.44 kcal/mole. The concentration dependency could be expressed double logarithmically.

• Microbiology and Biotechnology Letters
• /
• v.17 no.5
• /
• pp.468-474
• /
• 1989

The cultural condition for polysaccharide production by Pseudomonus detafietdii was studied. The optimal medium contains the following composition per liter of distilled water: glucose (25g/$\ell$), peptone (2.06g/$\ell$), KH$_2$PO$_4$(2g/$\ell$), MgSO$_4$.7$H_2O$ (2g/$\ell$), yeast extract (0.5g/$\ell$), CaCO$_3$(2.5g/$\ell$). The temperature and pH optimum were 3$0^{\circ}C$ and 6.5. The agitation speed was 300 rpm. 5.91g of polysaccharide was produced at the condition in flask culture.

• Microbiology and Biotechnology Letters
• /
• v.17 no.5
• /
• pp.421-428
• /
• 1989

A soil bacterium synthesizing an extremely viscous biopolymer was isolated and identified as Pseudomonas delafieldii. The optimal pH and temperature for the growth were 6.5 and 3$0^{\circ}C$, respectively. Maximum specific growth rate was 0.24 h$^{-1}$. The specific polysaccharide productivity, growth yield and product yield were 6.25 mg/g-cell/h, 54.5% and 38.39%, respectively. The polysaccharide was presumed to be $\beta$-glucan containing glucose and gluconolactone (1.9：1.0 in molar ratio) and 1.35 % acetyl group, Element analysis showed that it contained carbon (31.85%) and hydrogen (5.15%). The weight average molecular weight by GPC was 5.64$\times$10$^7$. The intrinsic viscosity was 42.84 dl/g.