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High cell density fed‐batch fermentation of Alcaligenes eutrophus was carried out for the production of poly(3‐hydroxybutyrate) (PHB) in a 60‐L fermentor. During the fermentation, pH was controlled with NH4OH solution and PHB accumulation was induced by phosphate limitation instead of nitrogen limitation. The glucose feeding was controlled by monitoring dissolved oxygen (DO) concentration and glucose concentration in the culture broth. The glucose concentration fluctuated within the range of 0–20 g/L. We have investigated the effect of initial phosphate concentration on the PHB production when the initial volume was fixed. Using an initial phosphate concentration of 5.5 g/L, the fed‐batch fermentation resulted in a final cell concentration of 281 g/L, a PHB concentration of 232 g/L, and a PHB productivity of 3.14 g/L · h, which are the highest values ever reported to date. In this case, PHB content, cell yield from glucose, and PHB yield from glucose were 80, 0.46, and 0.38% (w/w), respectively. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 28–32, 1997.

No abstract

Stenotrophomonas maltophilia T3-c, isolated from a biofilter for the removal of benzene, toluene, ethylbenzene, and xylene (BTEX), could grow in a mineral salt medium containing toluene, benzene, or ethylbenzene as the sole source of carbon. The effect of environmental factors such as initial toluene mass, medium pH, and temperature on the degradation rate of toluene was investigated. The cosubstrate interactions in the BTEX mixture by the isolate were also studied. Within the range of initial toluene mass (from 23 to 70 µmol), an increased substrate concentration increased the specific degradation of toluene by S. maltophilia T3-c. The toluene degradation activity of S. maltophilia T3-c could be maintained at a broad pH range from 5 to 8. The rates at 20 and 40 ºC were 43 and 83%, respectively, of the rate at 30 ºC. The specific degradation rates of toluene, benzene, and ethylbenzene by strain T3-c were 2.38, 4.25, and 2.06 µmol/g-DCW/hr.