摘要:

Filamentous cells ofErwiniasp. produced by growth in the presence ofD-serine possess nuclear bodies that are not dividing normally. The nuclear bodies can be highly convoluted and continuous throughout large portions of the filaments. Possible reasons for failure of the nuclear body to periodically divide and suggested relationships to division of the cell are discussed.

ISSN:0008-4166    

DOI:10.1139/m68-048

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Sorption between microbial cells and clay minerals was determined by measuring changes in particle size distribution with an electronic particle counter. Sorption increased as the valency of the cations present on the clay and in the suspending electrolyte increased. Neither the size, motility, or Gram reaction of bacteria nor the size of the clay appeared to influence sorption. Sorption occurred between bacteria and montmorillonite homoionic to monovalent cations only at pH 2 to 4, but did not occur at any pH with yeast cells, which sorbed only in the presence of trivalent cations. Heat-killed cells of yeast lost their ability to sorb, whereas cells killed with benzalkonium chloride did not. The possible implications of these results in sorption of microorganisms in natural habitats are discussed.

ISSN:0008-4166    

DOI:10.1139/m68-049

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The length of time muskmelon wilt soils were prewetted with water influenced the effectiveness of formaldehyde against populations of the wilt fungus,Fusarium oxysporumf.melonis, and as a control of wilt. Formaldehyde was least effective against populations of the wilt fungus in soils wetted for 24 hours before treatment and increasingly effective after 72 and 168 hours of wetting. Prewetting soils for different periods of time did not affect the susceptibility ofTrichodermaandPenicilliumspp. and members of Mucoraceae to formaldehyde.

ISSN:0008-4166    

DOI:10.1139/m68-050

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

An electronic computer was used to analyze the data obtained for 82 strains of streptococci, lactobacilli, and propionibacteria. The lactobacilli were divided into three major taxonomic groups which correspond to the subgeneraThermobacterium,Streptobacterium, andBetabacteriumdescribed by Orla-Jensen (14). Three clusters observed among the streptococcal strains also correlate with Sherman's (19) classification of pyogenic, fecal, and lactic groups of streptococci. The results are in agreement with present classifications. No justification for including the genusLactobacillusin the same family as genusPropionibacteriumwas found.

ISSN:0008-4166    

DOI:10.1139/m68-051

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Germination of the ascospores ofByssochlamys nivearequired a heat shock at 75° for 5 min, and acetate ion. Aeration and pH 4.0–4.5 further enhanced germination. No other trichloroacetic acid cycle compounds were stimulatory, and a survey of 18 amino acids and a number of miscellaneous compounds did not reveal any other germination factors. Extreme variation throughout the investigation suggested that other undisclosed factors were involved.

ISSN:0008-4166    

DOI:10.1139/m68-052

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Cornyebacterium diphtheriaewas grown in submerged culture using a new semisynthetic medium, and high-potency diphtheria toxins were produced. These toxins were purified before detoxification by formalin–lysine mixtures. The resultant toxoids possessed a high degree of purity (Lf/mg non-dialyzable nitrogen), gave good antigenic responses in animals, and showed no tendency to revert to toxin. Toxins which had been detoxified with formalin alone before purification, however, showed marked reversion when diluted and stored at 25 or 34 °C. When tested in guinea pigs the lysine-treated toxoids were shown to possess good immunizing capacity, and no significant decreases in the antigenic potencies were observed in samples stored for prolonged periods of time at elevated temperatures.

ISSN:0008-4166    

DOI:10.1139/m68-053

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The addition of α-methylmethionine to exponentially growing cultures ofSalmonella typhimuriumorEscherichia coliresulted in an immediate cessation of growth with low concentrations of the analogue. After a lag period, the length of which was dependent on the optical density of the culture, growth resumed at a rate characteristically slower than that of an untreated culture. Chemical analyses showed that the rate of synthesis of ribonucleic acid and protein byS.typhimuriumhad a pattern similar to the curve for optical density. However, deoxyribonucleic acid and cell numbers continued to increase at the normal rate for about 30 minutes, then slowed, and changed to the rate characteristic of cells treated with the analogue. Incorporation of thymine-14C, uracil-14C, and leucine-14C by the thymine auxotrophE.coli15T−confirmed the chemical analyses. After 25 minutes the cells of the culture treated with α-methylmethionine had incorporated only 15% of the uracil and 26% of the leucine as that of a control culture. The optical density was 30% that of a control culture. Thymine incorporation was 92% that of a control culture.

ISSN:0008-4166    

DOI:10.1139/m68-054

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Two isolates ofStemphylium radicinumwere grown in a chemically defined liquid medium. Both isolates grew best on organic nitrogen compounds and in the absence of a buffer grew poorly on ammonium nitrogen. KNO3was a good source of nitrogen for isolate No. 2, but not for No. 1.Xylose, sucrose, and glucose were the best carbon sources forS.radicinum, although isolate No. 1 produced more mycelium on pectin. Arabinose and cellulose were poor sources of carbon.Isolate No. 2 grew better than did isolate No. 1 on most media.The two isolates differed in their vitamin requirements. Isolate No. 1 was deficient for thiamine while isolate No. 2 did not need added vitamin for normal growth.

ISSN:0008-4166    

DOI:10.1139/m68-055

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The normal level of phosphorus inAnacystis nidulansis approximately 3.7 μg Pi/mm3cells. This value fell to 0.5 μg Pi/mm3cells under prolonged starvation. Even at low cellular phosphate levels, cells were viable and continued to divide slowly. With cells containing approximately 1.5 μg Pi/mm3cells a rapid dark uptake (15 minutes) of 0.8 μg Pi/mm3cells was found. Data obtained in the rapid dark fixation suggest that approximately 25% of the total cellular phosphorus is possibly bound on specific sites. Light had little effect on this first phase of phosphate uptake. The subsequent uptake to the normal phosphorus content per cell and return to normal growth rate required light and nitrogen.Coincident with the rapid dark phosphate incorporation, synthesis of ATP began and continued, rising far above the level of normal cells. The rate of ATP formation was not influenced by light, but was blocked by anaerobic conditions or several classical inhibitors of the electron transport chain.

ISSN:0008-4166    

DOI:10.1139/m68-056

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Escherichia intermediawas found to produce a β-lactamase that hydrolyzed several penicillin and cephalosporin C derivatives. Culture conditions affecting production of the enzyme were studied. The enzyme was non-inducible and cell-bound. Growth temperature, medium, and physiological age had a marked effect on production of the enzyme. Properties of the enzyme were studied with intact cells and with a cell-free preparation. Although the β-lactamase ofE.intermediawas different in some respects to that produced by gram-positive organisms, it was found to have properties similar to the β-lactamases of gram-negative organisms. 6-Aminopenicillanic acid was cleaved by the enzyme, but 7-aminocephalosporanic acid was resistant to cleavage. The rate of hydrolysis by intact cells and the purified preparation was influenced by the type of N-acyl sidechain of 7-aminocephalosporanic acid and 6-aminopenicillanic acid. The desacetoxy derivatives of cephalosporin C and cephalothin were hydrolyzed less rapidly than the parent compounds. The specific activity of the intact cells on cephalonium and methicillin was substantially less than that of the purified preparation.

ISSN:0008-4166    

DOI:10.1139/m68-057

出版商:NRC Research Press    

年代:1968

数据来源: NRC