ABC transporters are one of the largest membrane protein families discovered so far (Jumpertz et al., 2009). ABC transporters use the energy of ATP to catalyze the transport of a tremendous variety of substrates across biological membranes in a vectorial fashion. All ABC transporters analyzed so far are composed of two nucleotide-binding domains (NBD) and two transmembrane domains (TMD) that can be arranged in any possible combination. However, additional transmembrane segments or extended NBDs, raise the possibility that these extensions act as platforms to interact with additional proteins with functional or regulatory consequences.

ABC proteins are divided into three major classes corresponding to their overall quaternary structure organization. Class 1 contains ABC transporters whose transmembrane components and ABC domains are fused in a single polypeptide chain. Class 2 is comprised of ABC proteins lacking an integral membrane component or transport function. Class 3 identifies ABC transport systems where the ABC and membrane components are encoded on separate polypeptide chains and where an additional component essential for import processes can be present.

ABC transporters have been ascribed an important role in the development of multi drug resistance.

Jumpertz et al (2009) ABC Transporters: A Smart Example of Molecular Machineries. In: ABC Transporters in Microorganisms. Ponte-Sucre, A (Ed.). Caister Academic Press, Norfolk, UK

Further reading: ABC Transporters in Microorganisms

Labels: ABC transporters, drug resistance, membrane, transport

Bio-ethanol is considered as a potential alternative energy source to the conventional petroleum based fuels. Zymomonas mobilis is an efficient ethanol-producing bacterium and it is advantageous over Saccharomyces cerevisiae with respect to ethanol productivity and tolerance. Z. mobilis possesses nearly 100% theoretical ethanol conversion rate on glucose-based media, and about 70% theoretical yield from sucrose.

The reduced ethanol yield has been attributed to the formation of by-products such as levan, fructooligosaccharides and sorbitol. The efficiency of ethanol production by Z. mobilis from sucrose-based substrates can be improved by limiting the formation of by-products either by optimizing the fermentation conditions or genetic improvements of Z. mobilis. Recent strategies have been developed for the improved production of ethanol, while limiting the formation of levan.

from Geetha et al (2009) in Synthesis of Bacterial Polysaccharides as a Limiting Factor for Biofuel Production

Further reading: Bacterial Polysaccharides

Labels: bioethanol, biofuel, biotechnology, ethanol, polysaccharides, Saccharomyces, Zymomonas

Lab-on-a-chip (LOC) devices integrate and scale down laboratory functions and processes to a miniaturized chip format. Many LOC devices are used in a wide array of biomedical and other analytical applications including rapid pathogen detection, clinical diagnosis, forensic science, electrophoresis, flow cytometry, blood chemistry analysis, protein and DNA analysis. LOC devices can be fabricated from many types of material including various polymers, glass, or silicon, or combinations of these materials. A broad variety of fabrication technologies are used for LOC device fabrication. LOC systems have several common features including microfluidics and sensing capabilities. Microfluidics deals with fluid flow in tiny channels using flow control devices (e.g. channels, pumps, mixers and valves). Sensing capabilities, usually optical or electrochemical sensors, can also be integrated into the chip (Herold and Rasooly 2009. Lab-on-a-Chip Technology. Caister Academic Press ISBN: 978-1-904455-47-9).

Lab-on-a-chip technology is a rapidly expanding area of science. It has applications in biotechnology, medicine, clinical diagnostics, chemical engineering, and pharmaceutics. As the lab-on-a-chip systems increase in importance and complexity it is important for scientists to become familiar not only with the technology but also with the potential applications.

Bibliography:

1. Lab-on-a-Chip Technology: Fabrication and Microfluidics
2. Lab-on-a-Chip Technology: Biomolecular Separation and Analysis

Labels: lab on a chip, LOC, microfluidics