Characterization of enterobacteria by starch-gel electrophoresis of glucose-6-phosphate dehydrogenase and phosphogluconate dehydrogenase

Enzyme electrophoretic polymorphism differentiates invasive from non-invasive Chlamydia psittaci ruminant isolates

A group of 24 Chlamydia psittaci strains isolated from ruminants, belonging to serotype 1 and previously classified as invasive in a mouse model of virulence, was compared to a group of 10 non-invasive strains belonging to serotype 2 by using determination of glucose-6-phosphate and L-malate dehydrogenase zymotypes resulting of the infection of cells by these strains. The serotype 1 or invasive isolates represent a homogeneous group by sharing a unique zymotype which was not observed in the non-invasive strains. On the contrary, the serotype 2 or non-invasive isolates constitute a heterogeneous group in generating 2 different zymotypes. Zymotyping clearly distinguishes the ruminant strains from an avian C. psittaci and two C. trachomatis isolates studied for comparison. Our results suggest the usefulness of the studied molecular approach for chlamydiae typing. Furthermore, it can be used as marker of virulence within the C. psittaci strains isolated from ruminants.

An evaluation of allozyme amino acid substitutions for the study of molecular relationships in Providencia strains

Through analysis of molecular relationships in terms of amino acid substitutions, intra- and interspecies differentiations in Providencia alcalifaciens, P. stuartii and P. rustigianii were evaluated among the electrophoretic variants of three enzymes, L-malate dehydrogenase, acid phosphatase and esterase-beta a, chosen for their distinct pattern of polymorphism. For each enzyme, molecular relatedness among variants defined by two-dimensional electrophoretic profiles was examined through protein titration curves. P. stuartii strains appeared identical to each other and P. rustigianii strains were closely related, whereas the division of P. alcalifaciens strains into previously described zymotypes A1 and A2 was refined in molecular terms. A gradient of molecular interrelatedness between the species was observed for the three enzyme loci: with L-malate dehydrogenase, the three species appeared very closely related; with acid phosphatase, P. stuartii and P. alcalifaciens were more closely related to each other than to P. rustigianii; with esterase-beta a, P. alcalifaciens and P. stuartii appeared partially related, whereas no such relatedness was observed between these two species and P. rustigianii.

Methods for detecting recombinant DNA in the environment

The successful introduction of genetically modified and genetically engineered microorganisms into the environment requires a quantitative evaluation of the survival and dispersion of the microorganisms and specific gene(s) in the environment. The objective of this article is to examine the applicability, suitability, and significance of existing and new methods for detecting and monitoring the recombinant genes or organisms introduced into the environment. Conventional microbiological method(s) involving the selective and differential growth of microorganism(s) adn other quantitative approaches such as the most-probable-number (MPN) method and direct microscopic observation (e.g., acridine orange direct count analysis) have drawbacks and are not specific or universally applicable. Direct enumeration by immunofluorescence by the use of fluorescent dye seems more sensitive although still not perfect. However, the molecular methodologies such as the use of gene probes, plasmid epidemiology, antibiotic resistant marker strains, and protein electrophoresis and bacteriophage sensitivity are receiving more attention. As yet, the technology of DNA:DNA hybridization appears to be very useful, sensitive, and accurate for detecting and monitoring the microorganisms in the environment, although improvements are required. New approaches can be developed which may include biochemical signature compounds as well as gene cassettes to be used in a complementary fashion with conventional and molecular techniques for quantifying specific genotypes and genes in the environment.

Glucose-6-phosphate dehydrogenase alloenzymes and their relationship to pigmentation in Serratia marcescens

A comparative study of environmental and clinical isolates of Serratia marcescens was undertaken with regard to glucose-6-phosphate dehydrogenase (G6PD) electrophoretic mobility and the production of prodigiosin. Two electromorphs of G6PD with electrophoretic mobilities of 0.22 and 0.30 were detected. G6PD electrophoretic type showed a good correlation with the ability to produce prodigiosin.

Methods of multilocus enzyme electrophoresis for bacterial population genetics and systematics

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Enzyme markers for Vibrio cholerae: identification of classical, El Tor and environmental strains

Enzyme electrophoretic variants were studied in 49 strains of Vibrio cholerae using zymovar analysis. The following seven enzymes were selected for use: alanine dehydrogenase (ADH), isocitrate dehydrogenase (IDH), malate dehydrogenase (MDH), phosphoglucomutase (PGM), glucosephosphate isomerase (GPI), 6-phosphogluconate dehydrogenase (6PGDH) and glucose-6-phosphate dehydrogenase (G6PDH). The results indicated the presence of three main groups defined chiefly by their GPI and 6PGDH variants. The first group, defined by possessing the variants GPI-2 and 6PGDH-3, contained all the 01 serovar and E1T or biovar isolates from cholera cases. The second group, defined by possessing the variants GPI-3 and 6PGDH-2, contained all the 01 serovar and classical biovar isolates; the third group was heterogeneous and included the 01 serovar isolates from environmental sources as well as isolates of other serovars (the so called NAGs, non-agglutinable with 01 antisera or NCVs). It is thus now possible to separate the epidemic strains of 01 serovar from other members of this serovar isolated from the environment. Zymovar analysis deals with differences which are a direct expression of the genome and seems to be unaffected by gross phenotypic changes such as smooth-rough variation and phage resistance. It is a promising tool for investigating bacteriological and epidemiological questions, in particular the significance of an environmental reservoir of cholera.

Enzyme evolution in the Enterobacteriaceae

An immunological approach has been used for the study of alkaline phosphatase evolution in bacteria of the family Enterobacteriaceae. Antisera were prepared against alkaline phosphatase from Escherichia coli and Klebsiella aerogenes and tested against the unpurified alkaline phosphatases of 32 strains of enterobacteria by double diffusion and quantitative micro-complement fixation. The immunological relationships detected among the alkaline phosphatases of enterobacteria agree approximately with those reported for five other enzymes, as well as with the tryptic peptide pattern similarities found for two other enzymes, and with the relationships detected by interspecific deoxyribonucleic acid hybridization tests.

Mutation affecting plasmolysis in Escherichia coli

A temperature-sensitive mutant of Escherichia coli is described that at the restrictive temperature has lost the ability to plasmolyze. The mutation is located near pyrF.

Zone electrophoresis of enzymes in bacterial taxonomy

The electrophoretic mobilities in starch gels have been determined for eight enzymes in extracts of representative cultures of members of the family Enterobacteriaceae. These values were compared with each other and with those obtained from certain bacteria not in this family. The migrations of the eight enzymes were virtually identical for each of eight strains of Escherichia coli and for two species of Shigella. A number of these enzymes appeared to be identical in other organisms believed to be closely related to E. coli (Salmonella), and the number of differences increased in organisms which appeared to have lesser degrees of relatedness by other criteria (deoxyribonucleic acid base compositions, overall similarity).

Metabolism of carbohydrates by Pasteurella pseudotuberculosis

Cell-free extracts of Pasteurella pseudotuberculosis and P. pestis catalyzed a rapid and reversible exchange of electrons between pyridine nucleotides. Although the extent of this exchange approximated that promoted by the soluble nicotinamide adenine dinucleotide (phosphate) transhydrogenase of Pseudomonas fluorescens, the reaction in the pasteurellae was associated with a particulate fraction and was not influenced by adenosine-2'-monophosphate. The ability of P. pseudotuberculosis to utilize this system for the maintenance of a large pool of nicotinamide adenine dinucleotide phosphate could not be correlated with significant participation of the Entner-Doudoroff path or catabolic use of the hexose-monophosphate path during metabolism of glucose. As judged by the distribution of radioactivity in metabolic pyruvate, glucose and gluconate were fermented via the Embden-Meyerhof and Entner-Doudoroff paths, respectively. With the exception of hexosediphosphatase, all enzymes of the three paths were detected, although little or no gluconokinase or phosphogluconate dehydrase was present unless the organisms were cultivated with gluconate. The significance of these findings is discussed with respect to the regulation of carbohydrate metabolism in the pasteurellae, related enteric bacteria, and P. fluorescens.

Selection of Escherichia coli mutants lacking glucose-6-phosphate dehydrogenase or gluconate-6-phosphate dehydrogenase

Glucose is metabolized in Escherichia coli chiefly via the phosphoglucose isomerase reaction; mutants lacking that enzyme grow slowly on glucose by using the hexose monophosphate shunt. When such a strain is further mutated so as to yield strains unable to grow at all on glucose or on glucose-6-phosphate, the secondary strains are found to lack also activity of glucose-6-phosphate dehydrogenase. The double mutants can be transduced back to glucose positivity; one class of transductants has normal phosphoglucose isomerase activity but no glucose-6-phosphate dehydrogenase. An analogous scheme has been used to select mutants lacking gluconate-6-phosphate dehydrogenase. Here the primary mutant lacks gluconate-6-phosphate dehydrase (an enzyme of the Enter-Doudoroff pathway) and grows slowly on gluconate; gluconate-negative mutants are selected from it. These mutants, lacking the nicotinamide dinucleotide phosphate-linked glucose-6-phosphate dehydrogenase or gluconate-6-phosphate dehydrogenase, grow on glucose at rates similar to the wild type. Thus, these enzymes are not essential for glucose metabolism in E. coli.