摘要:

The response of the extreme halophile,Halobacterium cutirubrum, to suspension in graded concentrations of various salts was examined. Decrease in turbidity, release of cell constituents, and morphological alterations were used as measures of damage to cells. Sodium chloride, MgCl2, CaCl2, or CH3COONa in concentrations of 3.5 Mor higher were required to maintain the cells as rods, while much less concentrated solutions of the salts prevented gross release of cytoplasmic constituents. The requirement for salt was not solely a requirement for a suitable osmotic pressure. The salts which replaced NaCl in maintaining cellular integrity appeared to function on the basis of a mole for mole replacement of sodium ion by the cation. No evidence was found for differential release of large (nucleic acids) or small (inorganic phosphate) molecules when bacteria were suspended in decreasing concentrations of NaCl or MgCl2. A number of salts preserved cellular integrity ofH.cutirubrum, but high concentrations of NaCl were essential for growth of the bacterium.

ISSN:0008-4166    

DOI:10.1139/m63-020

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

It was found that certain bacterial and mammalian cells have similar receptor sites which react with natural antibodies present in human blood sera. Heated human sera which contain these antibodies are bacteriostatic toEscherichia coliandMycobacterium phleiand bactericidal toBacillus subtilis. This antibacterial effect is eliminated from heated human serum when the serum is treated with mouse cells.

ISSN:0008-4166    

DOI:10.1139/m63-021

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Microbiological studies of continuously frozen human feces and foodstuffs from sites of early Antarctic expeditions revealed viable organisms after 50 years. Aerobic and anaerobic sporeforming and non-sporeforming bacteria, actinomycetes, yeasts, and molds were recovered. No coliforms were encountered, and other enteric bacteria were of low incidence. The survival of microbiota expected to be present only as a minor component indicates that these have retained sufficient viability so as to comprise the major component of the populations.

ISSN:0008-4166    

DOI:10.1139/m63-022

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

A number of bacteria capable of lysingFusarium oxysporumwere isolated from soil. One of these, a strain ofBacillus cereus, was studied in detail. Living and dead fusarium mycelium as well as cell-wall preparations were digested by the bacterium. Chitin and the hyphae of a number of other fungi also served as carbon sources for the active organisms, but there was no lysis of species ofPythium,Streptomyces,Agrobacterium, orPseudomonas. Lysis appeared to be associated with chitinase and laminarinase activity ofB.cereus, but incubation of fungus mycelium with chitinase alone, or with chitinase in combination with laminarinase, proteases and cellulase, did not result in lysis. N-Acetylhexosamine appeared during the digestion. Evidence was obtained to suggest that lytic microorganisms could destroy fungal mycelium in sterile soil.

ISSN:0008-4166    

DOI:10.1139/m63-023

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Ten strains of naturally penicillin-resistantStaphylococcus aureus(obtained from patients), two in vitro derived resistant strains, and two sensitive strains, were grown at 37 C in Antibiotic Assay broth, and viable cell determinations were made at intervals. From these data, growth curves were plotted for each of the strains. The curves for the naturally penicillin-resistant and the sensitive strains are very similar. Little, if any, lag in growth of these strains occurred on transfer from maximum stationary-phase cultures to fresh medium. They grew at approximately the same rate during the logarithmic growth phase, which lasted for 3 to 4 hours; during the maximum stationary phase, about the same number of cells was present per milliliter in cultures of each of these strains. In contrast, the in vitro derived resistant strains underwent a lag of 2 to 6 hours on transfer to fresh medium and grew at a slower rate during the logarithmic growth phase. However, during the maximum stationary phase, which occurred after an incubation period of 24 to 32 hours, the cell titers were approximately the same as those of the naturally resistant and the sensitive strains. When grown in competition with either of the sensitive strains in Antibiotic Assay broth in the absence of penicillin, one of the naturally resistant strains persisted for 14 successive subcultures without any apparent change in ability to tolerate the antibiotic.

ISSN:0008-4166    

DOI:10.1139/m63-024

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

These studies are concerned with the growth interrelationships of mixed cultures of five soil organisms in soil extract and root extracts of 2-, 4-, and 8-week-old oats, soybeans, and wheat. Population changes ofAgrobacterium radiobacter,Arthrobacter citreus,Azotobacter chroococcum,Bacillus cereus, and aPseudomonassp. in pure and mixed culture were followed by plating on selective media.B.cereusandA.chroococcumgrew poorly alone or in mixed culture in the extracts. In soil extract,A.citreuspredominated over, or was nearly equal in number to, the Gram-negative forms (PseudomonasandAgrobacterium). In root extracts,Pseudomonassp. always predominated overA.citreusin mixed culture.A.radiobacterwas inhibited in mature root extracts (8-week-old plants) although in pure culture it recovered after a period. An antagonistic effect ofPseudomonassp. onA.chroococcumplated on nitrogen-free agar medium was found to be related to the kind of agar used.

ISSN:0008-4166    

DOI:10.1139/m63-025

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Plaques of phages PR-1001, PS-192, PR-590a, and PsR-1012 were clear, without halos, and with definite edges. Phage heads were approximately 60 mμ in diameter with short blunt tails. Phage titers in nutrient broth were stable during 452 days storage at 4 °C but were decreased considerably at 25 °C. After 46 days at 37 °C no surviving particles of any of the phages were detected. Ultraviolet inactivation of particles was not a first-order reaction. The pH stability range was between pH 7 and 11. Inactivation at 50 °C and 55 °C was least in saline, more marked in nutrient broth, and most severe in distilled water. Protection against inactivation was a function of the mono- and di-valent cation concentration. Separately the cations provided insignificant protection. NH4+in combination with Ca++or Mg++inactivated phage particles as did also Cu++, Hg++, Al+++, and Fe+++in solutions of NaCl. Heat-inactivated particles showed collapsed heads that indicated a loss in DNA.

ISSN:0008-4166    

DOI:10.1139/m63-026

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

A number of molds and bacteria were screened for their ability to degrade quercitrin. The molds, but not the bacteria, were particularly active and produced carbon monoxide. The degradation of quercitrin is dependent upon the synthesis of an inducible glycosidase (quercitrinase). This enzyme is synthesized by only a few members of theAspergillus flavusgroup. Two of these strains synthesized quercitrinase and excreted it and other enzymes into the culture medium. Maximum production of quercitrinase was obtained with organic nitrogen sources such as yeast extract or phytone. Quercitrinase is induced by readily metabolized flavonols and flavonol-glycosides. The glycosidase is quite specific, liberating the rhamnose from the 3-position of quercitrin and myricitrin and the 7-position of robinin. The aglycone, quercetin, is subsequently metabolized to carbon monoxide and the depside of phloroglucinol-carboxylic acid and proto-catechuic acid. Evidence is also presented for an alternative pathway for the metabolism of the flavonol nucleus.

ISSN:0008-4166    

DOI:10.1139/m63-027

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

A rapid slide flocculation test using bentonite particles sensitized with salmonella O somatic antigen extracts has been described. A polyvalent antigen was also prepared using a number of salmonella O extracts thereby making the test useful for the screening of either a monovalent antibody or covering a wide range of O groups. The sensitized test antigen can be lyophilized and, when rehydrated, yields reproducible results. This investigation marks the first reported successful sensitization of bentonite with polysaccharide material. The practical application of this test is now undergoing investigation.

ISSN:0008-4166    

DOI:10.1139/m63-028

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

A study was made of the numbers and kinds of microorganisms in the root zone of wheat and soybeans grown in the greenhouse at three ranges of temperature: 55–60°, 70–75°, and 85–90 °F. Numbers of bacteria in the rhizosphere and rhizoplane of wheat decreased as the temperature increased, whereas numbers in the root-free soil and on soybean roots increased with increased temperature. The same relationships held for methylene blue reducing, glucose-fermenting, and ammonifying bacteria and those requiring amino acids for optimal growth. Generic analysis of bacterial isolates showed that the percentage of Gram-negative rod-forming organisms increased with a rise in temperature in root-free soil and on soybean roots but decreased on wheat roots. On the other hand, the incidence of Gram-positive and pleomorphic organisms decreased in soil and on soybean roots with higher temperature and increased on wheat roots.Fungal isolations from washed root segments showed a greater incidence ofMucor,Rhizopus,Rhizoctonia, andGliocladiumon soybeans at the high temperature whereas species ofFusariumandCylindrocarponwere more prevalent at the low temperature. With wheat the most striking feature was the predominance of non-sporing dark species at the high temperature and of non-sporing hyaline types at the low temperature.The number of soil nematodes decreased in the rhizospheres of both plants with increased temperature, the effect being more pronounced with soybeans. With this crop all except one of the genera recognized decreased in number, whereas with wheat, the incidence of certain nematodes such as species ofHelicotylenchus,Boleodorus, andAphelenchoidesdid not change with temperature.The results suggest that temperature exerts a direct effect on the microorganisms in the root zone and an indirect effect by influencing plant growth.

ISSN:0008-4166    

DOI:10.1139/m63-029

出版商:NRC Research Press    

年代:1963

数据来源: NRC