SPOTLIGHT

& Tracking Succession Stages in BiofilmDevelopment Using Quantitative Texture Analysis

Biofilms in natural and engineered environments are dynamic

ecosystems harboring a complex microbial community. Attach-

ment and initial growth are the important first steps for the

development of a biofilm on a clean surface. Once established,

biofilms undergo maturation. Milferstedt et al. have developed a

quantitative tool to track the development of biofilm architecture

during initial growth and subsequent maturation. Large scale

images (13.3� 8.7 mm2) were analyzed over periods of 10 weeks

using quantitative texture analysis. The authors present

first indicators of developmental succession cycles initiated by

sloughing of large amounts of biomass. The evaluation of mixed

culture biofilms examined at larger spatial and temporal scales will

provide the necessary framework to understand the fundamental

relationship between biofilm architecture and function in natural

and engineered systems. Page 889

DOI: 10.1002/bit.21998

& HPTFF: Concentration-Purification-Formulation in a Single Step

New recovery operations are being investigated to address the need

for process step reduction and cost-of-goods reduction. In this

context, the novel membrane technology High Performance

Tangential Flow Filtration (HPTFF), a two-dimensional unit

operation that selectively separates solutes on the basis of both size

and charge, is shown to successfully enable concentration,

purification and formulation in a single step. This is illustrated

with a Fab 2 real feedstream application from Lebreton, Brown and

van Reis, with an emphasis on development methodology and

process optimization. HPTFF is shown to enable robust and

reproducible operations with high throughput and high selectivity.

When compared with a conventional recovery scheme, the

proposed process results in the elimination of one chromato-

graphic step, a 12% yield improvement and significant purification

cost reduction. Page 964

DOI: 10.1002/bit.21999

& Pluronic Accumulates in Significant Amountsin Mammalian Cells

Pluronic F-68(PF-68) is widely used in large-scale mammalian cell

culture to protect cells from shear stress. In order to study the fate

of this medium additive in cell culture, Gigout, Buschmann and

Jolicoeur have developed a fluorescein-based PF-68. These authors

have clearly demonstrated that PF-68 enters CHO cells and

chondrocytes (the resident cells in cartilage), and possibly

accumulates in the endocytic pathway. When grown in suspension,

chondrocytes showed a significant uptake of PF-68 that was 5-fold

more than that of CHO suspension cells. It was also observed that

CHO cells were able to eliminate intracellular fluorescent PF-68 but

chondrocytes were not. These findings will aid in the optimization

of culture medium containing PF-68 for high-density mammalian

cell culture, where cell uptake can affect the PF-68 concentration in

the culture medium, and Pluronic uptake may influence cell

behavior and utility for particular applications such as cartilage

repair. Page 975

DOI: 10.1002/bit.22000

& Supercritical Processing

In this work, Della Porta and Reverchon proposed an innovative

technology for the production of drug/polymer microspheres with

controlled size and distribution. The process described as

‘‘supercritical fluids extraction of emulsion’’ uses supercritical

carbon dioxide (SC-CO2) to extract the dispersed phase of an

emulsion producing a suspension from which the microparticles

can be recovered. The authors focused their attention on the

production of spherical PLGA microspheres loaded with an anti-

inflammatory drug with mean sizes ranging between 1 to 3mm and

very narrow size distributions. These results were mainly obtained

due to the very short processing time (30 min) and the very fast

precipitation route obtained in SC-CO2 processing that may

prevent droplet coalescence or aggregation phenomena typically

occurring during the conventional solvent evaporation process. A

solvent residue smaller than 40 ppmwas also monitored in the final

product at the optimized operating conditions. Page 1020

DOI: 10.1002/bit.22001

Published online in Wiley InterScience

(www.interscience.wiley.com).

� 2008 Wiley Periodicals, Inc. Biotechnology and Bioengineering, Vol. 100, No. 5, August 1, 2008