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Biomedical subjects

R H Olsen

Publications and source records attributed to R H Olsen.

63 records · Page 4Linked to original sources
PubMed1969

Alteration in bacterial morphology by optochin and quinine hydrochlorides.

Incubation of washed bacterial and ribosomal suspensions with optochin or quinine hydrochloride caused an increase in the turbidity of the suspensions and the appearance of electron-dense cytoplasmic aggregates in the treated cells. These effects were more pronounced with optochin hydrochloride than with quinine hydrochloride, and they did not correlate with the relative sensitivities of different bacteria to growth inhibition by optochin or quinine.

Bacillus subtilis↗
PubMed1968

Conversion of mesophilic to psychrophilic bacteria.

The minimum temperature of growth of the mesophilic bacterium Pseudomonas aeruginosa has been significantly lowered from approximately 11 degrees to 0 degrees C. This shift in the minimum temperature of growth was accompanied by a corresponding decrease in the maximum temperature of growth. Transfer of this genetic characteristic by a transducing phage grown on a psychrophile or by ultraviolet mutagenesis was used to accomplish these shifts in range of growth temperature.

Bacteriophages↗
PubMed1968

Altered diaphorase activity in optochin-resistant pneumococci.

Methylene blue (MB) reductase activities of washed cell suspensions and of cell-free extracts prepared from optochin-resistant mutant pneumococci were two times greater than and four to eight times more resistant to optochin inhibition than those of similar preparations from the optochin-sensitive parent strains. With whole cells, optochin hydrochloride was approximately four times more potent than quinine hydrochloride in inhibiting MB reductase activity. However, with cell-free extracts, both drugs had similar inhibitory activities. Glucose uptake was not affected by optochin hydrochloride, and both optochin-sensitive and optochin-resistant pneumococci had similar glucose uptake patterns. Diaphorase activities of cell-free extracts prepared from optochin-resistant pneumococci were two times greater than and four to eight times more resistant to optochin inhibition than those of cell-free extracts prepared from the optochin-sensitive parent strains. Flavin concentrations of cell-free extracts prepared from optochin-sensitive and optochin-resistant strains were similar.

Cell-Free System↗
PubMed1968

Purification and properties of mutant and wild-type diaphorases from Diplococcus pneumoniae.

Optochin-resistant mutant and wild-type diaphorases were purified approximately 300-fold by a combination of batch adsorption and column chromatography with diethylaminoethyl cellulose, and were characterized with regard to their pH optima, sensitivity to optochin inhibition and heat inactivation, Michaelis constants with flavine mononucleotide (FMN) and reduced nicotinamide adenine dinucleotide (NADH), and inhibition constants with optochin hydrochloride. The pH optima of the purified diaphorases were similar, but the purified diaphorases from the optochin-resistant strains were approximately four to five times more resistant to heat inactivation at 45 C than was the wild-type diaphorase. Purified diaphorase preparations from the optochin-resistant pneumococci had greater activities per milligram of protein and were more resistant to optochin inhibition than the preparation from the optochin-sensitive pneumococcus. Michaelis constants for FMN and NADH were similar; however, the inhibition constants of the optochin-resistant diaphorases were four to eight times greater than that of the optochin-sensitive diaphorase. Optochin hydrochloride produced a noncompetitive type of inhibition with FMN as substrate but a competitive type of inhibition with NADH as substrate. Optochin hydrochloride produced an approximately 10-fold increase in the Michaelis constant for NADH. The concentration of drug required to produce this effect was, however, greater with the mutant diaphorases than with the wild-type diaphorase. Optochin hydrochloride quenched the fluorescence of riboflavine. This phenomenon did not appear to be related to the diaphorase-inhibitory activity of the drug, however, since the pH requirements of the two reactions were different. Quenching of riboflavine fluorescence by optochin hydrochloride increased with a rise in pH, whereas inhibition of diaphorase activity by optochin hydrochloride was greater at pH 6.8 than at pH 7.6.

Adsorption↗
PubMed1968

Conditional temperature-sensitive restriction of Pseudomonas bacteriophge CB3.

Restriction of Pseudomonas bacteriophage CB3 growth on some Pseudomonas aeruginosa hosts was studied. On restricting hosts, growth of this phage was severely inhibited below 32 C and hence was temperature-sensitive. Investigation of this phenomenon revealed that restricting hosts were not killed as a consequence of their infection under nonpermissive conditions. The ability of some hosts to restrict showed segregation in sexual crosses between restricting and nonrestricting hosts. However, the pattern of restriction among various hosts differed with the phage in question when other phages were compared with CB3. Temperature-shift experiments indicated that blockage of an early event in the phage lytic cycle occurred when restricting conditions were imposed on cells infected with CB3. This blockage could be eliminated by holding at permissive conditions until the cold-sensitive step was bypassed or by pulsing restricting cells for 5 min at 37 C.

Bacteriophages↗
PubMed1968

Characteristics of bacteriophages attacking psychrophilic and mesophilic pseudomonads.

Ten Pseudomonas phage were isolated by sewage enrichment. Five psychrophilic and five mesophilic phage were selected for a description of some of their biological properties. In addition to growth on psychrophilic hosts, the psychrophilic phage studied were also able to grow on a mesophilic host within its growth temperature range. Latent periods for psychrophilic phage at 3.5 C were 6 to 12 hr and at 25 C were 30 to 60 min. Mesophilic phage had a latent period of 85 to 190 min at 25 C and 35 to 85 min at 37 C. Psychrophilic phage were significantly more heat-sensitive than the mesophilic phage. Of all the parameters studied, only thermal sensitivity correlated with growth at 3.5 C. Phage used in this study had a deoxyribonucleic acid base composition ranging from 39.6 to 68.2% guanine plus cytosine, deduced from melting temperature measurements.

Bacteriophages↗
PubMedDate not supplied

Metabolic diversity of aromatic hydrocarbon-degrading bacteria from a petroleum-contaminated aquifer.

We characterized bacteria from contaminated aquifers for their ability to utilize aromatic hydrocarbons under hypoxic (oxygen-limiting) conditions (initial dissolved oxygen concentration about 2 mg/l) with nitrate as an alternate electron acceptor. This is relevant to current intense efforts to establish favorable conditions for in situ bioremediation. Using samples of granular activated carbon slurries from an operating groundwater treatment system, we isolated bacteria that are able to use benzene, toluene, ethylbenzene, or p-xylene as their sole source of carbon under aerobic or hypoxic-denitrifying conditions. Direct isolation on solid medium incubated aerobically or hypoxically with the substrate supplied as vapor yielded 10(3) to 10(5) bacteria ml-1 of slurry supernatant, with numbers varying little with respect to isolation substrate or conditions. More than sixty bacterial isolates that varied in colony morphology were purified and characterized according to substrate utilization profiles and growth condition (i.e., aerobic vs. hypoxic) specificity. Strains with distinct characteristics were obtained using benzene compared with those isolated on toluene or ethylbenzene. In general, isolates obtained from direct selection on benzene minimal medium grew well under aerobic conditions but poorly under hypoxic conditions, whereas many ethylbenzene isolates grew well under both incubation conditions. We conclude that the conditions of isolation, rather than the substrate used, will influence the apparent characteristic substrate utilization range of the isolates obtained. Also, using an enrichment culture technique, we isolated a strain of Pseudomonas fluorescens, designated CFS215, which exhibited nitrate dependent degradation of aromatic hydrocarbons under hypoxic conditions.

Bacteria↗
PubMedDate not supplied

Evidence for the evolution of a single component phenol/cresol hydroxylase from a multicomponent toluene monooxygenase.

We have previously reported on the organization of a unique toluene-3-monooxygenase pathway for the degradation of alkyl-substituted petroleum hydrocarbons including characteristics of the second step in the pathway transforming phenols to catechols. In the present work we have focused on the regulation and unusual genetic organization of this metabolic step. In particular, we have sequenced the 3-kb DNA interval between the region encoding the tbuD gene product (phenol/cresol hydroxylase) and part of the toluene-3-monooxygenase operon of strain PKO1. Then, various regions of this DNA were fused to a LacZ expression system to ascertain the location of the tbuD gene promoter and the binding site for its regulator, TbuT. The 5' end for transcripts for the putative promoter of the tbuD gene was also analyzed using primer extension analysis. Collectively, these results revealed that the promoter was located 2.5-kb upstream of the region encoding the tbuD gene product whose N-terminal region had been previously determined by peptide sequencing. Remarkably, the intervening 2.5-kb region showed sequence identity to results we reported previously for a multi-subunit toluene-2-monooxygenase cloned from a different bacterium, strain JS150, for which phenols are also substrates and effectors. When the DNA sequence for the tbuD gene and its contiguous 2.5-kb upstream region were compared to the entire toluene-2-monooxygenase sequence cloned from strain JS150, a promoter proximal region encoding three reading frames showed 99% identity to subunits for the toluene-2-monooxygenase operon. Within the contiguous tbuD gene region, however, DNA sequence homology was reduced to 64% overall identity and deduced amino acid sequence homology was only 21% similar. Although regions internal to the tbuD gene showed homology to corresponding toluene-2-monooxygenase subunits, domains associated with the putative functions proposed for such subunits were deleted. We believe that these results suggest that through evolution either tbuD was derived from the 2-monooxygenase pathway by deletions and molecular rearrangements, or alternatively the tbuD gene recruited part of the 2-monooxygenase pathway and its regulatory system which is activated by benzene, alkyl-substituted benzenes and phenols.

Amino Acid Sequence↗