A recent effort to improve malic acid production by Saccharomyces cerevisiae by means of metabolic engineering resulted in a strain that produced up to 59 g liter(-1) of malate at a yield of 0.42 mol (mol glucose)(-1) in calcium carbonate-buffered shake flask cultures. With shake flasks, process parameters that are important for scaling up this process cannot be controlled independently. In thi...

The extradiol dioxygenase diversity of a site highly contaminated with aliphatic and aromatic hydrocarbons under air-sparging treatment was assessed by functional screening of a fosmid library in Escherichia coli with catechol as substrate. The 235 positive clones from inserts of DNA extracted from contaminated soil were equivalent to one extradiol dioxygenase-encoding gene per 3.6 Mb of DNA sc...

Protist communities found in the hindgut of subterranean termites (Rhinotermitidae) historically have been quantified and identified using a variety of methods, thus making comparisons between studies difficult We examined four saline solutions and compared protist estimates by using two different cell-counting platforms. Estimates of protist populations were greater using a hemo­ cytometer cou...

In order to design efficient fouling mitigation strategies in granular anaerobic membrane bioreactors (G-AnMBR), foulant characteristics and their role have be thoroughly investigated. Raw mixed liquor of G-AnMBR was split by sieving into granules supernatant fractions at 0.125 mm. Then, the potential reversibility different samples (granules, raw liquor) were assessed measuring critical fluxes...

We investigate in detail both the deracemization reaction rate and maximum conversion of (R,S)-1-phenylethanol a bubble column deactivation rates enzymes involved, alcohol dehydrogenase (ADH) NADH oxidase (nox2). Instead predicted ellipsoidal shape bubbles, we observe spherical all our experiments. Calculated values for area-specific mass transfer coefficient kLa sparged, but not stirred, solut...

SPARG/AIRFIX is developed by Mohtar and Rahbeh in 2001 as a practical unsaturated flow and multiphase transport model that can be used for the design and operation of sparging and soil vapor extraction systems [5]. The model uses first order kinetics to represent the mass transfer among the aqueous, gaseous, solid, and NAPL phases. The theoretical basis of the model is build on the fact that so...

Bioprocess scale-up is a fundamental component of process development in the biotechnology industry. When scaling up a mammalian cell culture process, it is important to consider factors such as mixing time, oxygen transfer, and carbon dioxide removal. In this study, cell-free mixing studies were performed in production scale 5,000-L bioreactors to evaluate scale-up issues. Using the current bi...

Membrane fouling in UF/MF is a problem that has been attracting considerable intellectual and engineering resources over almost 40 years. A lot of efforts, such as high tangential flows, vibration, air sparging and the like, have been taken to minimize its negative impact on the performance of UF/MF filters [1]. All these efforts are associated with increased operating and maintenance costs, an...

At high viable cell concentrations in large-scale mammalian cell culture processes, the accumulation of dissolved carbon dioxide (dCO(2), typically quantified as an equilibrium gas-phase concentration) becomes problematic as a result of low CO(2) removal rates at reduced surface-to-volume ratios. High dCO(2) concentrations have previously been shown to inhibit cell growth and product formation ...