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PubMedDate not supplied

[Effect of different storage methods on the viability of Halobacterium salinarum].

It has been established that the studied halobacteria are cryolabile and sensitive to the sharp change in osmotic pressure of the environment. Optimal temperature of their storage is +20 degrees C for suspension of native cells and +4 degrees C for the cells in anabiotic state. Their storage medium should have optimal osmotic pressure and contain NaCl and K+, Mg+ ions. It is recommended to keep halobacteria during one year in a form of suspension in nutrient medium, and during at least 4 years in lyophilized state. Other long-term storage methods: L-drying, freezing at low temperatures, are not recommended for halobacteria.

Culture Media↗
PubMedDate not supplied

[Biphasic nature of the light-dependent transport of C14-alanine into Halobacterium holobium cells].

Biphase character of photoinduced pH change in H. halobium R1 suspension cells is shown: in the first illumination period pH rises and only afterwards it decreases. pH increase is accompanied by the introduction of C14-alanine into the cells, while the decrease by its yield up to the level lower than the "dark" one ("negative" photoeffect). The bi-phase character of transport processes seems to be explained by the reversible character of light-dependent bacteriorodopsin proton pump in H. halobium R1 cells.

Alanine↗
PubMed1992

The alpha-operon equivalent genome region in the extreme halophilic archaebacterium Haloarcula (Halobacterium) marismortui.

The genome region of the extreme halophilic archaebacterium Haloarcula marismortui equivalent to the alpha-operon of Escherichia coli has been characterized. In H. marismortui, the alpha-operon was found to be located immediately upstream from the S9 gene cluster. The gene order in the halobacterial alpha-operon, given according to the gene products, is tRNA(Ser), HmaS13, HmaS4, HmaS11, and HmaRp alpha. Compared to the corresponding operon from E. coli, the halobacterial gene organization differs in (i) the presence of a gene for tRNA(Ser) (GCU), (ii) the reversed order of the genes for the ribosomal proteins HmaS11 and HmaS4, and (iii) the absence of the gene coding for the ribosomal protein L17. The primary structure of HmaRp alpha shows high similarity to a subunit of eukaryotic RNA polymerase II (YeaRpB3, HsaRpB33), whereas the similarity to the eubacterial alpha-subunit of RNA polymerase is only weak.

Amino Acid Sequence↗
PubMedDate not supplied

[Photogeneration of a 2-vector transmembrane proton gradient in Halobacterium halobium R1 cells].

Analysing 4 phases of light-dependent change of pH in cell suspension of H. halobium R1 it has been found that an increase of pH I when light is switched on and a decrease of pH II during further illumination are proportional to the light effect and are energy-dependent. Neutralization of these changes (phases III and IV) proceeds spontaneously in the darkness. These data show that the transmembrane gradient of protons is generated in two directions--delta pH and +delta pH, simultaneous presence of which points to the local character of one of them. Generation of -delta pH associated with light energy utilization by the cells is considered as a result of neutralization of the negative charge and +delta pH1 (latent), appearing due to a change in bacteriorodopsin conformation under illumination. It may be also suggested that the yield of protons from the cells of pHII and generation of +delta pH result from the discoupling of photoprocesses and energy utilization by the cells, containing bacteriorodopsin.

Bacteriorhodopsins↗
PubMedDate not supplied

[Photoinduced inhibition and stimulation of respiration in cells of Halobacterium halobiums kinetics, action spectra, relationship to photoinduction of deltapH].

Along with the inhibition illumination also causes the stimulation of the respiration of H. halobium R1 cells. When light is switched off photoinhibition of respiration (PIR) decays much faster (tau 1/2=12 sec) than photostimulation (PSR) (tau 1/2=60 sec). This allows the evaluation of the contribution of the each phase into the total change of the respiration rate. PIR prevails in neutral and alkaline media (at pH 6.8 the amplitude ratio of PSR/PIR=0.3). At the same conditions light induced alkalization of the medium is observed, which at high light intensities is followed by acidification. The half rise time of PIR is 0.5 divided by 0.8 sec under excitation with short light flashes at 18C and pH 6.8. When pH of the medium is reduced the rate of dark respiration decreases, PSR amplitude increases, PIR is almost not changed and light-induced alkalinization of the medium decreases. At pH 5.5 PSR prevails: at light of 10(5) erg/(cm(2).s) the ratio PSR/PIR=2. The maximum value of PIR and PSR at 18C reaches 20-30 percent of the dark respiration level. Uncouplers (CCCP, DNF) and inhibitor (DCCD) of phosphorylation suppress PIR and light induced alkalinization of the medium and significantly (5-7 times at Ph 6.8) increase PSR and light induced acidification. The action spectra show that bacteriorhodopsin is responsible for all the observed light induced changes of O2 and H+ exchange; carotinoids do not participate in sensibilization. It is suggested that photophosphorylation is necessary for PIR and that PSR is caused by the rise of internal pH due to light induced efflux of protons mediated by bacteriorhodopsin.

Bacteriorhodopsins↗