Bacterial Cell Factories

E. R C. Rocha, P. Guerdoux-Jamet, I. Moszer, A. Viari, and A. Danchin, Implication of gene distribution in the bacterial chromosome for the bacterial cell factory. J. Biotech. 78, 209-219 (2000). 

Part B Multipurpose Bacterial Cell Factories offers four chapters on some of the most widely used industrial microorganisms. Escherichia coli (Chapter 5), Corynebacterium glutamicum (Chapter 6), Bacillus subtilis (Chapter 7), Pseudomonas putida (Chapter 8) have evolved into synthetic platforms with a broad range of applications. Their product portfolios include fine chemicals, bulk chemicals, drugs, flavors and fragrances, materials, fuels, therapeutic and diagnostic... 

Li, H. and Cao, Y. (2010) Lactic acid bacterial cell factories for gamma-aminobutyric acid. Amino Acids, 39, 1107-1116. 

In this chapter, an array of multiple applications of LAB for the elaboration of fermented foods and production of industrially interesting metabolites such as food ingredients, nutraceutics, and commodity chemicals was presented. Additionally, new biotechnological approaches for the production of these compounds were described. The metabolic versatility of this bacterial group demonstrates their potential for their use as cell factories beyond their classical use as food starter cultures and preservatives or as probiotics. These bacteria have been systematically assayed for novel specific traits or applications due to the availability of new molecular techniques and the consumers demands for healthier foods. LAB, considered the horsepower of the food industry, have been the focus of numerous studies to increase their product yields and repertoire. 

Here, a portfolio of high-value metabolites produced by wild-type LAB displaying applications in the food, pharmaceutical, and chemical industries was presented. New approaches in the production of commodity chemicals, to replace natural resources, by recombinant LAB strains were briefly addressed. The versatility of this bacterial group demonstrates their potential to be used as cell factories beyond their classical use as food starter cultures, preservatives, or as probiotics. As shown, LAB are systematically screened for novel specific traits or applications thanks to the availability of novel molecular techniques and consumers demands for healthier, tailor-made foods. It is clear that application of LAB as the workhorses of the food industry has expanded to their use as microbial factories to increase yields and product repertoire which were earlier limited by the natural capacity of the existing bacterial biosynthetic pathways. Emerging fields include the design and creation of synthetic microbes to create novel metabolic pathways for new products. Will LAB be included in this next challenging approach ... 

RGURE 25-18 Chromosome partitioning in bacteria, (a) All replication is carried out at a central replication factory that includes two complete replication forks, (b) The two replicated copies of the bacterial chromosome are extruded from the replication factory into the two halves of the cell, possibly with each newly synthesized origin bound separately to different points on the plasma membrane. Sequestering the two chromosome copies in separate ceil halves facilitates their proper segregation at ceil division. 

In many bacterial species, zinc storage is apparently not a major mechanism in attaining homeostasis, the exception being cyanobacteria, which detoxify and store zinc in a metallothionein. A more common way of ridding the cell of excess zinc is by exporting it. The importance of this is clearly illustrated by the highly Zn -resistant bacterium, Ralstonia metalUdurans, isolated from a decantation tank in a zinc factory, and which has a minimal inhibitory Zn " ... 

The sensitivity of supramolecular assemblies such as microtubuli and flagellin suggests that we may expect that cells are quite sensitive to pressure. Without much hesitation we may consider the cell as a molecular factory. This is supported by the observations on viruses. Very small pressures induce changes that make viruses biologically inactive although the structure may be little affected. The molecular adaptation mechanisms that play a role in the composition of bacterial membranes may be interpreted along the same lines. 

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