Production of unusual bacterial polyesters by Pseudomonas oleovorans through cometabolism

Abstract Pseudomonas oleovorans is an adaptable, aerobic bacterium that can produce a wide range of storage polyesters (poly-β-hydroxyalkanoates, PHAs). With few exceptions, the PHAs obtained when this bacterium is grown with single organic substrates capable of polymer production are generally copolymers. With two different polymer-producing substrates the copolymers formed contain units derived from each substrate often in direct proportion to the amounts in the medium. With such substrates or with non-producing substrates, or with non-growth substrates, the ability of P. oleovorans to utilize different types of individual organic compounds can be classified into three different categories, as follows: group A—the organic compound can support both growth and polymer production; or group B—the organic compound can support growth but not polymer production; or group C—the organic compounds cannot support growth. For organic compounds in groups B and C, new and unusual copolymers containing units derived from these substrates can often be obtained if that compound is cofed with a good polymer-producing substrate for P. oleovorans , such as either octanoic acid or nonanoic acid. The PHAs obtained by this type of cometabolism from a variety of such substrates are described.     

PTC and PROP behave differently in tests of discrimination from their solvents

Better discrimination was possible between phenylthiocarbamide (PTC) solutions and the pure solvent when the solvent was a tasteless low- concentration NaCl solution to which the subject had adapted than when the solvent was purified water. The reverse was true for 6-n- propylthiouracil (PROP). The differences in discrimination for PROP and PTC in the different solvents were caused by differences in the intensity and persistence of aftertastes, rather than a more intense perception of the PTC and PROP tastes per se. This has consequences for traditional approaches to measuring taste sensitivity, as well as indicating that PTC and PROP are not necessarily equivalent indicators of 'taster' versus 'non-taster' status.      

Stimulation of human T cell colony growth by a lymphocyte colony enhancement factor derived from lymphocyte subpopulations

Blood mononuclear cells (MNC) develop into T cell colonies when the cells are sensitized with PHA and seeded in a two-layer soft agar system. Conditioned medium (CM) derived from MNC enhanced lymphocyte colony formation when it was added to the culture system. CFU-TL appear to be stimulated into colony formation by molecules secreted by lymphocyte subpopulations contained in the seeded cells. In this study, human peripheral blood MNC were fractionated by a battery of techniques into adherent, E+, CD4+, CD8+, B and null cells. CM was prepared from each of the subpopulations and its effects on T cell colony growth assayed. All the lymphocyte subpopulations were found to generate lymphocyte colony enhancement factor (LCEF). After several purification procedures, CM prepared from CD4 and CD8+, displayed LCEF activity corresponding to proteins of molecular weight 30-40 and 100-140 kD.