putida strain BS202P1 and P. putida strain S1 (Balashova et al., 2001), the present study suggests that strain PPH has two distinct and specific hydroxylases: 1-hydroxy-2-naphthoic acid hydroxylase and salicylate-1-hydroxylase. In conclusion, the observed properties Everolimus order suggest that 1-hydroxy-2-naphthoic acid hydroxylase from Alcaligenes
sp. strain PPH is a heat-stable, single-component flavoprotein aromatic hydroxylase specific for 1-H2NA. J.D. thanks CSIR, Government of India, for a Senior research fellowship and P.P. thanks BRNS, DAE, Government of India, for the research grant. “
“An Escherichia coli strain that exhibits a double auxotrophy for l-alanine and d-alanine was constructed. During growth in the presence of the dipeptide l-alanyl-l-alanine (Ala–Ala), this was fully consumed with concomitant extracellular accumulation of l-alanine in a twofold molar concentration compared with the dipeptide. This finding indicates that the strain not only can hardly degrade l-alanine but has an export system(s) for l-alanine. To obtain access
to the system, we chemically mutagenized the l-alanine-nonmetabolizing strain and isolated mutants with increased Ala–Ala sensitivity. Two such mutants accumulated l-alanine up to 150–190 mM in the cytoplasm with a reduced rate of l-alanine export relative to the parent strain in the presence of Ala–Ala. Furthermore, when chloramphenicol was added together with Ala–Ala, the parent strain accumulated l-alanine in the cytoplasm to a level Chorioepithelioma similar to that observed in the mutants in the absence of chloramphenicol. LDE225 cell line In contrast, the intracellular l-alanine level in the mutants did not change irrespective of chloramphenicol treatment. From these results, we conclude that E. coli has an inducible l-alanine export carrier, together with a second, as yet unidentified, mechanism of alanine export. Various l-amino acids are now produced by fermentative processes using producer strains of Corynebacterium glutamicum or Escherichia coli (Takors et al., 2007). In these processes, the products synthesized intracellularly
from sugars are eventually accumulated in the medium. Thus, it has long been thought that these bacteria should possess some efflux systems for amino acids, despite the exporters not being identified. However, the presence of such systems has recently been demonstrated experimentally: lysine, threonine, isoleucine and glutamic acid exporters in C. glutamicum (Vrljic et al., 1996; Simic et al., 2001; Kennerknecht et al., 2002; Nakamura et al., 2007), and homoserine, cysteine, threonine, arginine, leucine and aromatic amino acid exporters in E. coli (Zakataeva et al., 1999; Daßler et al., 2000; Livshits et al., 2003; Nandineni & Gowrishankar, 2004; Kutukova et al., 2005; Doroshenko et al., 2007; Eggeling, 2009). In C. glutamicum, since it has been found that a lysine-exporterless mutant exhibited growth arrest in the presence of lysine-containing dipeptide (Vrljic et al.