Conversion of chloramphenicol degradation products by tyrosine aminotransferase from Flavobacteria

The tyrosine aminotransferase of Flavobacterium strain CB 60, strain CB 6 and F. devorans r - a partially purified enzyme was used - is able to deaminate oxidatively p-aminophenylalanine and the intermediate products of chloramphenicol degradation p-nitrophenylserine and p-aminophenylserine. The aminotransferases of the strains CB 6 and CB 60 also convert p-aminophenylserinol. p-Nitrophenylserinol only reacts with the enzyme from strain CB 6. Determination of substrate specificity from strain CB 6 shows that an alcoholic group in C3 position (ring proximal) and to a lower degree an alcoholic group in C1 position (ring distal) decrease the turnover rate. Based on its broad substrate specificity the tyrosine aminotransferase has the ability not only to metabolize physiological compounds but also degradation products of chloramphenicol.     

Purification and characterization of 2-halocarboxylic acid dehalogenase II from Pseudomonas spec. CBS 3.

2-Halocarboxylic acid dehalogenase II from Pseudomonas spec. CBS 3 (EC 3.8.1.2), which had been cloned in E. coli Hb 101 was purified to electrophoretic homogeneity from crude extracts of E. coli Hb 101 clone 1164. Ammonium sulfate fractionation and three subsequent chromatographic purification steps yielded a pure enzyme in a 230-fold enrichment. The relative molecular masses as determined by gelfiltration on Superose 12 and SDS-polyacrylamide gel electrophoresis were 64,000 Da for the holoenzyme and 29,000 Da for the subunit. The isoelectric point, determined by isoelectric focusing, was at pH 6.2. Substrate specificity towards chlorinated and brominated substrates was limited to short chain monosubstituted 2-halocarboxylic acids. Fluorocompounds were not converted. The reaction proceeded best at a pH above 9.5 and at a reaction temperature of 40-45 degrees C.     

Characterization of filament forming Bacillus strains isolated from bulking sludge

Summary Filament-forming bacilli were isolated from bulking sludge. They were physiologically very similar. However, they developed into rhizoid or non-rhizoid colonies. According to their morphological, physiological, and genetical properties the isolates were identified as Bacillus mycoides and Bacillus cereus.     

Effects of 1,1'-hexamethylene-bis-[(5-p-chlorophenyl)-biguanide] on the genome and on the synthesis of nucleic acids and proteins in the bacterial cells

The strongly effective bactericidal compound 1,1'-hexamethylene-bis-[(5-p-chlorophenyl)-biguanide] (HCG), which is used as a disinfectant alterates the DNA of B. subtilis as shown in the rec assay, induced auxotrophic mutants in E. coli B and causes prophage induction in Micrococcus lysodeikticus 53-40 (N5). In vivo experiments with E. coli B have demonstrated that HCG extensively breaks down bacterial DNA and interacts with the synthesis of cellular DNA to the similar extent as found for N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). The structural integrity of ribosomes and of ribosomal subunits remains intact in the presence of HCG.     

Degradation of (−)-ephedrine byArthrobacter globiformis

Summary A bacterium utilizing the alkaloid (–)-ephedrine as its sole source of carbon was isolated by an enrichment-culture technique from soil supplemented with (–)-ephedrine hydrochloride. The bacterium was identified asArthrobacter globiformis by morphological and physiological studies.The following metabolites of (–)-ephedrine degradation were isolated from the culture fluid: methylamine, phenylacetylcarbinol (1-hydroxy-2-oxo-1-phenyl-propane), methylbenzoylcarbinol (2-hydroxy-1-oxo-1-phenyl-propane), acetaldehyde, benzoic acid, pyrocatechol, and cis,cis-muconic acid.A pathway for the bacterial degradation of (–)-ephedrine has been proposed.In memory of Professor Dr. Konrad Bernhauer.