Donn J. Kushner

Haloarcula hispanica spec. nov. and Haloferax gibbonsii spec, nov., Two New Species of Extremely Halophilic Archaebacteria

Summary After an extensive taxonomic study for extremely halophilic rods ( Torreblanca et al., 1986), several groups appeared which did not fit with any previously described species of Halobacteria. In the present work two strains, Y27 (= ATCC 33960) and MA2.38 (= ATCC 33959), representatives of the two most distinct new groups, were studied in detail, and two new species are proposed.

Nutritional control of pigment and isoprenoid compound formation in extremely halophilic bacteria

Summary1.Cells of the extremely halophilic bacteria, Halobacterium cuti-rubrum and H. halobium grown in a chemically defined medium (BSMK) were red due to the presence of bacterioruberins (maxima, 370, 388, 494 and 527 nm). Adding 0.1% glycerol to BSMK stimulated growth, but cells rapidly lost bacterioruberins becoming greyish purple in the stationary phase. Acetone extracts of these cells were yellow with a broad absorption band at 360–390 nm, partly attributable to retinal. In BSMK medium with or without glucose, the bacterioruberin concentration increased until maximal growth was reached, then fell rapidly.2.In complex medium (CM) cells formed less bacterioruberins than in BSMK. Adding 0.1% glycerol to CM stimulated growth but did not change pigmentation; adding glucose only slightly stimulated growth but greatly increased bacterioruberin formation. Exposure to visible light did not affect growth or pigmentation.3.Addition of glycerol or glucose to BSMK increased the formation (relative to squalene) of dihydrosqualene, tetrahydrosqualene, and vitamin MK8. Higher levels of these compounds were found in cells grown in CM than in BSMK. Though glycerol decreased the formation of bacterioruberins it increased the formation of β-carotenes. Glucose increased the formation both of bacterioruberins and β-carotene. A preliminary hypothesis to account for the effects of nutrients on pigmentation is presented.

Nutrition of the Halophilic Archaebacterium, Haloferax volcanii

Summary A synthetic medium containing glycerol and succinate as carbon sources, NH4Cl as nitrogen source, thiamine and biotin, as well as salts, supports growth of Haloferax volcanii and other halophilic archaebacteria. A number of single carbon compounds can also support growth, as can single nitrogen compounds (urea, histidine and glutamate). Some of the latter can support much richer growth than NH4Cl. In a complex medium, cells were able to grow in lower NaCl concentrations (1.0 M NaCl) than in the defined medium, though in both media the upper range of growth was approximately the same (4.0–4.5 M NaCl.)

Effects of cellulose on growth enzyme production and ultrastructure of a cellulomonas species

Cellulomonas sp. (NRCC 2406) was grown on complex medium (peptone-tryptone-yeast extract) alone, or with the addition of different celluloses (solka floc, avicel, CF 11 cellulose or Whatman No. 1 filter paper) and/or glucose. Cultures growing on the complex medium without cellulose produced low levels of endo- and exo-cellulases and very little β-glucosidase. Adding cellulose stimulated growth, as measured by cellular protein or by viable counts, and also stimulated production of cellulases. Adding glucose in the prescene of cellulose inhibited growth and cellulose breakdown. Glucose also inhibited attachment of growing cells to cellulose fibres. Electron microscope studies showed that Cellulomonas sp. adhered to the cellulose fibers. In the presence of cellulose in the media, the cells developed a thicker outer layer which probably helps in the adhesion process.

Extreme Environments: Are There Any Limits to Life?

Many microorganisms can grow in conditions that seem extreme to us: boiling and freezing water, extremes of pH, of salt concentration, of radiation, of other environmental variables. With some ingenious adaptations, the basic mechanisms of “extreme life” seem similar to those of more “normal” life. There do seem to be limits, however, to the environments in which microorganisms can grow. All need relatively abundant amounts of liquid water. Growth does not take place within ice, or at water activities (aw’s) below 0.6, even though living forms can survive much drier and much colder conditions for many years. Unless comets contain substantial amounts of liquid water, life, similar to any that we know, probably cannot exist or arise in them.

A bacteriophage of a moderately halophilic bacterium

A bacteriophage of an aerobic, gram-negative, rod-shaped halophilic bacterium, provisionally named Pseudomonas sp. G3, is described. The phage has a head and a tail and is similar in appearance to Salmonella phage Beccles. It infects its bacterial host at all salt concentrations in which the bacteirum is able to grow. In contrast to phages of halophilic archaebacteria, the newly-described phage is relatively stable in the absence of salt. It also infects Vibrio costicola and two unidentified halophilic eubacteria.

Polyamines in moderately and extremely halophilic bacteria

Abstract Cells of the moderate halophile, Vibrio costicola , growing in a chemically defined minimal medium containing glutamate, glucose and vitamins, were devoid of polyamines. Cells growing in a complex medium (preteose peptone + tryptone) contained substantial amounts of several polyamines. These seemed to be incorporated from the medium itself, either directly or after some modification. The presence of polyamines in cell of V. costicola did not increase their osmotic stability when they were placed in lower NaCl concentrations than that of the growth medium. Addition of polyamines to chemically defined minimal medium did not affect growth of V. costicola . Another moderate halophile, NRCC 41227, produced spermidine in chemically defined minimal medium and contained other polyamines after growth in proteose peptone + tryptone. Less halophilic Vibrio species, Vibrio alginolyticus and Vibrio cholerae , produced a number of polyamines during growth in chemically defined minimal medium. Several extremely halophilic archaebacteria produced no, or only traces of, polyamines during growth on a medium containing yeast extract. Our results confirm the fact that not all bacteria contain polyamines; they also show that the polyamine content of some of these bacteria is directly determined by that of the growth medium.

Protein turnover in a psychrotrophic bacterium

Protein breakdown in pulse-labelled and longlabelled cells of Arthrobacter S1-55, a psychrotrophic bacterium, has been assessed at different temperatures. The temperature at which the cells were grown and labelled affected the breakdown of pulsed-labelled but not long-labelled proteins. Inhibitors of ATP synthesis inhibited proteolysis. Miscoding antibiotics stimulated the production of rapidly degradable proteins.

Characterization of the bacterial enzyme “Thromboplastinase”☆

Abstract 1. 1. The action of the enzyme “thromboplastinase” has been compared with that of a Clostridium perfringens culture filtrate and purified α-toxin, and of a Bacillus cereus phospholipase. 2. 2. All enzymes released acid-soluble phosphorus from purified lecithin. In the conentrations used, the clostridial enzymes were most active. In addition, all enzymes liberated acid-soluble phosphorus from human brain thromboplastin and reduced the clot-accelerating activity of thromboplastin. In these cases, however, thromboplastinase was most active. 3. 3. The acid-soluble compounds released by thromboplastinase, by the B. cereus phospholipase, and by C. perfringens lecithinase were identified as phosphocholine, phosphoethanolamine,sb and phosphoserine and were measured quantitatively. Thromboplastinase liberated phosphocholine most actively, and the other compounds approximately equally. The clostridial enzymes liberated as much phosphocholine as did thromboplastinase, but less phosphoethanolamine, and little or no phosphoserine. The B. cereus phospholipase released small amounts of all three compounds. 4. 4. The destruction of thromboplastic activity does not appear primarily due to the lecithinase activity of thromboplastinase, but rather to the breakdown of phosphatidylethanolamine and possibly phosphatidylserine by this enzyme. The relation between thromboplastinase action and that of the other enzymes studied, especially that of the B. cereus phospholipase, is discussed.

Energetic basis of development of salt-tolerant transport in a moderately halophilic bacterium, Vibrio costicola

Active transport of α-aminoisobutyric acid (AIB) in Vibrio costicola utilizes a system with affinity for glycine, alanine and, to some extent, methionine. AIB transport was more tolerant of high salt concentrations (3–4 M NaCl) in cells grown in the presence of 1.0 M NaCl than in those grown in the presence of 0.5 M NaCl. The former cells could also maintain much higher ATP contents than the latter in high salt concentrations.Transport kinetic studies performed with bacteria grown in 1.0 M NaCl revealed three effects of the Na+ ion: the first effect is to increase the apparent affinity (Kt) of the transport system for AIB at Na+ concentrations <0.2 M, the second to increase the maximum velocity (Vmax) of transport (Na+ concentrations between 0.2 and 1.0 M), and the third to decrease the Vmax without affectig Kt (Na+ concentrations >1.0 M). Cells grown in the presence of 0.5 M or 1.0 M NaCl had similar affinity for AIV. Thus, the differences in salt response of transport in these cells do not seem due to differences in AIB binding. Large, transport-inhibitory concentrations of NaCl resulted in efflux of AIB from cells preloaded in 0.5 M or 1.0 M NaCl, with most dramatic efflux occurring from the cells whose AIB transport was more salt-sensitive. Our results suggest that the degree to which high salt concentrations affect the transmembrane electrochemical energy source used for transport and ATP synthesis is an important determinant of salt tolerance.