Modulation of different forms of glutamine synthetases inRhizobium phaseoli and their possible role in nitrogen fixation

The effect of a number of compounds structurally related to glutamic acid and other nitrogenous compounds on the composition of three forms of glutamine synthetase (GS) inRhizobium phaseoli has been examined in detail. Amino acids like glutamic acid, glutamine, and a fixed source of nitrogen like ammonium chloride did not alter the relative glutamine synthetase composition.l-Methioninedl-sulfoximine (MSX), a glutamate analogue, significantly repressed the synthesis of GSIII to a greater extent.,N-oxalyl,-diaminopropionic acid (ODAP), another glutamate analogue, selectively stimulated the synthesis of GSII, and the effect of ODAP on GSII synthesis was greatly enhanced in the presence of ethylenediamine or ammonium chloride. Ethylenediamine itself caused a predominant synthesis of GSIII.-Cyanoalanine-grownR. phaseoli did not synthesize GSI. The synthesis of the three different glutamine synthetases can thus be differentially modulated.     

A new name and a new species in MexicanRuellia (Acanthaceae)

Based on pollen and floral morphology,Blechum grandiflorum is transferred toRuellia, and the nameR. mirandana is proposed for this species. A new species,Ruellia tuxtlensis, is described which is distinguishable fromR. mirandana by its longer spike and elliptic bracts. It is presently known only from the lowlands of Veracruz, Mexico.     

Identification and characterization of three forms of glutamine synthetase unique to Rhizobia

Glutamine synthetase (GS) activities of Rhizobia were chromatographically resolved into three distinct forms, GSI, GSII, and GSIII on DEAE cellulose, being eluted with 0.3M, 0.5M and 0.8M KCl, respectively. GSIII was the major form inR. leguminosarum andR. phaseoli. InR. meliloti, however, GSI was the major form. The three forms of GS were also distinguished on the basis of (a) rapid heat inactivation of GSII, (b) insensitivity of GSI to inhibitors, (c) marked inhibition of GSII by thymidine, and (d) inability of Zn⁺⁺ to inhibit GSIII. The three forms of GS are also distinct molecular entities and are unique to Rhizobia.     

Binding of mercuric and other heavy metal ions by microbial growth media

Ion-specific electrodes were used to study the binding of Hg²⁺, Pb²⁺, Cu²⁺, and Cd²⁺ ions to widely used bacterial growth media (Nutrient broth, trypticase soy broth, the medium of Foot and Taylor [6] and of Nelsonet al.[12]) and to media components [yeast extract, peptone, tryptone, proteose peptone, and casamino acids (acid hydrolyzed casein)]. Volatilization of Hg²⁺ from aqueous solutions could be prevented by any of the growth media or their components. All media bound large amounts of Hg²⁺, Pb²⁺, and Cu²⁺, but much less Cd²⁺. Of the media components, casamino acids showed the most binding activity for all metal ions; the relative affinity of other media components to different ions varied with the cation studied. In general, the Irving-Williams [8] series for cation affinity to organic ligands was followed: Hg²⁺>Pa²⁺ Cu²⁺ Cd²⁺.After adding 20 ppm of Hg²⁺, Pb²⁺, or Cu²⁺ (concentrations inhibitory to the growth of most microorganisms) to the growth media, 80 ppb or less remained as free cations in the solution. This might suggest that such ions enter bacterial cells as organic complexes, or that bacterial cells can compete successfully with growth media for the bound ions.     

Draft genome sequencing and functional annotation and characterization of biofilm-producing bacterium Bacillus novalis PD1 isolated from rhizospheric soil

Antonie van Leeuwenhoek - Biofilm forming bacterium Bacillus novalis PD1 was isolated from the rhizospheric soil of a paddy field. B. novalis PD1 is a Gram-positive, facultatively anaerobic,...