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Expression of the RND-Type Efflux Pump AdeABC in Acinetobacter baumannii Is Regulated by the AdeRS Two-Component System. Isabelle Marchand, 2004. Osmotic Stress Response: Quantification of Cell Maintenance and Metabolic Fluxes in a Lysine-Overproducing Strain of Corynebacterium glutamicum. Cristian A. Varela, 2004.Osmotic stress diminishes cell productivity and may cause cell inactivation in industrial fermentations . The quantification of metabolic changes under such conditions is fundamental for understanding and describing microbial behavior during bioprocesses . We quantified the gradual changes that take place when a lysine-overproducing strain of Corynebacterium glutamicum is grown in continuous culture with saline gradients at different dilution rates . The use of compatible solutes depended on environmental conditions; certain osmolites predominated at different dilution rates and extracellular osmolalities . A metabolic flux analysis showed that at high dilution rates C . glutamicum redistributed its metabolic fluxes, favoring energy formation over growth . At low dilution rates, cell metabolism accelerated as the osmolality was steadily increased . Flexibility in the oxaloacetate node proved to be key for the energetic redistribution that occurred when cells were grown at high dilution rates . Substrate and ATP maintenance coefficients increased 30- and 5-fold, respectively, when the osmolality increased, which demonstrates that energy pool management is fundamental for sustaining viability . Homotrimeric, ß-Stranded Viral Adhesins and Tail Proteins. Peter R. Weigele, 2003. Highly Conjugative pMG1-Like Plasmids Carrying Tn1546-Like Transposons That Encode Vancomycin Resistance in Enterococcus faecium. Haruyoshi Tomita, 2003.A total of 12 VanA-type vancomycin-resistant enterococci, consisting of 10 Enterococcus faecium isolates and two Enterococcus avium isolates, were examined in detail . The vancomycin resistance conjugative plasmids pHT  (65.9 kbp), pHTß (63.7 kbp), and pHT (66.5 kbp) were isolated from each of three different E . faecium strains . The plasmids transferred highly efficiently between enterococcus strains during broth mating and were homologous with pMG1 (Gmr; 65.1 kb) .
L-Proline Accumulation and Freeze Tolerance in Saccharomyces cerevisiae Are Caused by a Mutation in the PRO1 Gene Encoding  -Glutamyl Kinase.Yuko Morita, 2003.We previously isolated a mutant which showed a high tolerance to freezing that correlated with higher levels of intracellular L-proline derived from L-proline analogue-resistant mutants . The mutation responsible for the analogue resistance and L-proline accumulation was a single nuclear dominant mutation . By introducing the mutant-derived genomic library into a non-L-proline-utilizing strain, the mutant was found to carry an allele of the wild-type PRO1 gene encoding -glutamyl kinase, which resulted in a single amino acid replacement; Asp (GAC) at position 154 was replaced by Asn (AAC) . Interestingly, the allele of PRO1 was shown to enhance the activities of
-glutamyl kinase and
-glutamyl phosphate reductase, both of which catalyze the first two steps of L-proline synthesis from L-glutamate and which together may form a complex in vivo . When cultured in liquid minimal medium, yeast cells expressing the mutated
-glutamyl kinase were found to accumulate intracellular L-proline and showed a prominent increase in cell viability after freezing at -20°C compared to the viability of cells harboring the wild-type PRO1 gene . These results suggest that the altered
-glutamyl kinase results in stabilization of the complex or has an indirect effect on
-glutamyl phosphate reductase activity, which leads to an increase in L-proline production in Saccharomyces cerevisiae . The approach described in this paper could be a practical method for breeding novel freeze-tolerant yeast strains .
Community-Level Physiological Profiling Performed with an Oxygen-Sensitive Fluorophore in a Microtiter Plate. Jay L. Garland, 2003.Community-level physiological profiling based upon fluorometric detection of oxygen consumption was performed on hydroponic rhizosphere and salt marsh litter samples by using substrate levels as low as 50 ppm with incubation times between 5 and 24 h . The rate and extent of response were increased in samples acclimated to specific substrates and were reduced by limiting nitrogen availability in the wells .
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