A streptomycin-resistant variant of Xanthomonas campestris was grown in defined nutrient-deficient media in both batch and continuous culture. The production, composition and viscosity of the extracellular polysaccharide (xanthan) synthesized by this strain were influenced by the fermentation time and nutrient exhaustion in batch culture and by the dilution rate in continuous culture. The speci...

The effect of specific growth rate μ on the production of Vibrio vulnificus nuclease was investigated in fed-batch cultures of a high-yield recombinant Escherichia coli. A pseudo-exponential feeding method for controlling μ was employed to obtain the desired data. It was found that the nuclease content of cells γP varied with μ, with a maximum occurred at μ = 0.05 h−1; however, the specific nuc...

Transcription of the dnaA gene of the cyanobacterium Synechocystis sp. strain PCC 6803 is light dependent and yields a monocistronic mRNA, as determined by Northern analysis. Surprisingly, mutants with inactivated dnaA were viable. In batch cultures under standard conditions, the mutants grew like the wild type and did not show an aberrant phenotype. We conclude that, unlike the situation in ot...

The optimal physical factors affecting enzyme production in an airlift fermenter have not been studied so far. Therefore, the physical parameters such as aeration rate, pH, and temperature affecting PLA-degrading enzyme production by Actinomadura keratinilytica strain T16-1 in a 3 l airlift fermenter were investigated. The response surface methodology (RSM) was used to optimize PLA-degrading en...

A simple feeding strategy was developed and successfully employed for nutritional control in a 2-L fed-batch culture of hybridoma cells. A previously developed stoichiometric model for animal cell growth was used to design a supplemental medium for feeding. Undialyzed fetal bovine serum and trace metals (Fe(2+), SeO(3) (2-), Li(+), Zn(2+), and Cu(2+)) were fed to the cells periodically in addit...

A high beta-glucosidase (BGL)-producing strain, Stereum hirsutum, was identified and isolated and showed a maximum BGL activity (10.4 U/ml) when cultured with Avicel and tryptone as the carbon and nitrogen sources, respectively. In comparison with other BGLs, BGL obtained from S. hirsutum showed a higher level of activity to cellobiose (V(max) = 172 U/mg, and k(cat) = 281/s). Under the optimum ...

In order to see the effect of CO(2) inhibition resulting from the use of pure oxygen, we carried out a comparative fed-batch culture study of polyhydroxybutyric acid (PHB) production by Ralstonia eutropha using air and pure oxygen in 5-L, 30-L, and 300-L fermentors. The final PHB concentrations obtained with pure O(2) were 138.7 g/L in the 5-L fermentor and 131.3 g/L in the 30-L fermentor, whic...

BACKGROUND In comparison with phototrophic growth, heterotrophic conditions can significantly increase growth rates, final cell number and cell mass in microalgae cultures. Neochloris oleoabundans is a microalga of biotechnological interest that accumulates lipids under phototrophic and nitrogen-limited conditions. Heterotrophic flask culture experiments were conducted to identify carbon source...

The production of lactic acid from date juice by Lactobacillus caseisubsp. rhamnosus in batch and fed-batch cultures has been investigated. The fed-batch culture system gave better results for lactic acid production and volumetric productivity. The aim of this work is to determine the effects of the feeding rate and the concentration of the feeding medium containing date juice glucose on the ce...

Batch culture of Ralstonia eutropha using the recycled gas closed circuit culture system was conducted in order to develop a practical fermentation system for industrial autotrophic culture for poly (hydroxybutrate) production. The gas phase of the culture system consisted of substrate gas so that gases in this culture could be recycled as long as the amount of the gas consumed would be repleni...