Complementation and the physiological characteristics of the ts mutants of Pseudomonas aeruginosa phage SM

Seventy three temperature-sensitive mutants of Pseudomonas aeruginosa SM phage have been obtained using different mutagens and assigned to thirteen complementation groups. Representative mutants of each group have been studied with the aim of characterizing tentatively the time of genes expression in infected bacteria. Two genes appear to function during the first minutes after infection, whereas the remaining genes are needed for late functions. Most of the temperature-sensitive functions in the different mutants are reversible, i.e. they become active when the infected cells are shifted-down to the permissive temperature.     

Hydrogen Production by CO2 Deprived Photoautotrophic Chlamydomonas reinhardtii Cultures

Biochemistry (Moscow) - Light-dependent hydrogen production by microalgae attracts attention of researchers because of the potential practical application. It is generally recognized that...     

Mapping of pgi and gpd genes involved in C-1 assimilation in the obligate methylotroph Methylobacillus flagellatum

Homologous matings with plasmids R68.45 and pULB113, and also with Hfr type donor were employed for mapping pgi and gpd genes involved in C-1 metabolism in the obligate methylotroph Methylobacillus flagellatum. A preliminary map of the late chromosomal region was constructed on the basis of these experimental results. The C-1 markers were linked to methionine and leucine auxotrophy and nalidixic acid resistance markers. The phenomenon of retrotransfer, or shuttle transfer of chromosomal markers by Inc P1 plasmids, revealed earlier, was demonstrated for M. flagellatum.     

Differences in possible TCA cycle replenishing pathways in purple non-sulfur bacteria possessing glyoxylate pathway

Photosynthesis Research - Pathways replenishing tricarboxylic acid cycle were divided into four major groups based on metabolite serving as source for oxaloacetic acid or other tricarboxylic acid...     

NADP+-dependent glutamate dehydrogenase from the obligate methylotroph methylobacillus flagellatum

Abstract NADP-dependent glutamate dehydrogenase (GDH; E.C.1.4.1.4) was purified from an obligate methylotroph Methylobacillus flagellatum using ammonium sulphate precipitation, DEAE-Sepharose and dye-ligand Procion red HE3B column chromatography and Sephacryl S-200 gel-filtration. The M_r of the native enzyme was estimated to be 300 000 (±5000). The enzyme consists of six identical subunits with an M_{r of} 47 000 (±3000) (SDS-PAGE). The enzyme has a pH optimum of 8.0 when participating in amination and 9.5 in deamination. Michaelis-Menten kinetics were observed for both reactions. The apparent K_m values were 1.33 mM, 0.032 mM, 11.5 mM, 7.0 mM and 0.014 mM for α-ketoglutarate, NADPH, NH₄⁺, glutamate and NADP⁺, respectively. The enzyme was highly specific for all the substrates and was insensitive to inhibitors. It plays an exclusively anabolic role in the cells.     

Laboratory scale photobioreactor

Summary A photobioreactor using three concentric glass cylinders, with a light source mounted on the axis within them is described. The space between two innermost cylinders is used as a waterjacket, while the culture of phototrophic microorganisms is in the chamber between the outer cylinder and the middle one. This chamber is also equipped with a stirrer. Rhodobacter capsulatus has been grown in the device at biomass concentration up to 550 mg/l without light limitation.     

Identification and characterization of the pqqDGC gene cluster involved in pyrroloquinoline quinone production in an obligate methylotroph Methylobacillus flagellatum

Abstract Pyrroloquinoline quinone is a prosthetic group of bacterial methanol dehydrogenases as well as some alcohol and glucose dehydrogenases. Genes involved in pyrroloquinoline quinone production have previously been cloned from the representatives of the α and γ subdivisions of the Proteobacteria. We report identification and the sequence of the pqqDGC gene cluster in the obligate methylotroph, Methylobacillus flagellatum , which belongs to the β subdivision. The deduced products of the pqq genes from M. flagellatum appear to be more similar to their counterparts from non-methylotrophic species of the γ subdivision than to a facultative methylotroph of the a subdivision. A non-polar mutation in pqqG was constructed and resulted in a strain impaired in growth on methanol. This mutant accumulated a detectable amount of intracellular pyrroloquinoline quinone, but in contrast to the wild type, did not excrete pyrroloquinoline quinone into the culture medium. The possible role of PqqG is discussed.     

l-threonine transport in the obligate methylotroph Methylobacillus flagellatum KT

Abstract The accumulation of l -threonine by the methylotrophic bacterium Methylobacillus flagellatum KT occurs via a specific system that is capable of transporting l -threonine against a 100-fold concentration gradient. This transport system demonstrates the following kinetic parameters: K _m= 0.2 mM and V _max= 2.5 nmol/min/mg of cells (dry weight). The activity of the system is inhibited by oxidative phosphorylation uncouplers and valinomycin. Cytoplasmic l -threonine does not leak from the cell, but bacteria are capable of exchanging exogenous l -threonine for its intracellular counterpart.