摘要:

Thirty-three strains ofClostridium perfringenswere screened for bacteriocin production. Four bacteriocin-producing strains were detected by plating the supernatant fluids of these cultures on all available strains ofC.perfringensseeded in semisolid agar and noting zones of bacterial inhibition after subsequent incubation. The spectrum of sensitive strains differed for each bacteriocin as did the degree of bacterial sensitivity to each bacteriocin.One bacteriocin and one indicator strain were chosen for further study. This bacteriocin, which was spontaneously produced during the logarithmic growth phase of the bacteriocinogenic strain, was not inducible with ultraviolet light but was sensitive to heat and trypsin. Adsorption of bacteriocin to the indicator strain was not detected and electron microscopy did not reveal any particulate substance associated with bacteriocin activity. The degree of bacterial inhibition was dependent on the titer of the bacteriocin used, and the age of the indicator culture appeared to influence its relative response to bacteriocin treatment.

ISSN:0008-4166    

DOI:10.1139/m71-001

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The fatty acid composition of some thermotolerant strains ofDactylaria gallopavaisolated from coal spoil tips has been compared with that of the type strain ofD.gallopava, the original isolation of which was from diseased turkey poults. In addition, the fatty acids of the mesophilic fungiDactylaria ampulliformeandScolecobasidiumspp. were analyzed. The scolecobasidia andD.gallopavahad the same qualitative fatty acid pattern, though quantitatively there were differences, the scolecobasidia having more highly unsaturated lipids thanD.gallopava.D.ampulliformecontained the triply unsaturated γ-linolenic acid and eicosatrienoic acid, and in this respect differed from the scolecobasidia andD.gallopava, which appeared unable to synthesize trienoic acids.

ISSN:0008-4166    

DOI:10.1139/m71-002

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

A tissue culture assay method is described in which monkey kidney cell cultures were protected by antibacterial immune serum against infection bySalmonella typhi,Neisseria meningitidis, orNeisseria gonorrhoeae. The neutralization of the bacterial challenge was specific since neither heterologous nor normal sera gave significant protection to the tissue cultures.

ISSN:0008-4166    

DOI:10.1139/m71-003

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The potassium content ofHalobacterium halobiumwas studied in media in which the K+was growth-limiting and in media containing excess K+. In BSM medium (76.5 μg/ml K+) cells grew until all K+was cell bound. In BSMK medium (1.1 mg/ml K+) cells grew more abundantly; about one-third of the available K+became cell-bound. Adding glucose or vitamins to BSMK medium stimulated growth and could stimulate K+binding. However, rapid death in the presence of vitamins reduced the potassium-binding ability of most cultures. Living cells bound very large amounts of K+. After growth stopped in BSM medium they contained about 0.4 g K+per gram protein; that is, about 30% of the cell's dry weight consisted of K+. This is probably the lowest K+concentration supporting life of these cells. In BSMK medium, and in the BSM medium in the early stages of growth before all K+was cell-bound, considerably higher levels of K+were reached. Altering the pH or the NaCl concentration of the medium within the limits that still permitted growth did not affect the cells' K+contents.K+was released when cells in culture died. Non-growing cells incubated at 37 °C in salts solutions without K+or any energy source lived for up to 3 days, and with K+for at least 7 days. Their K+contents remained constant until they died, and then fell. If Mg2+was omitted from the salts solution cells died more rapidly than in the absence of K+. Dead cells did not lyse or release protein into the external medium.

ISSN:0008-4166    

DOI:10.1139/m71-004

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

InMicrococcus lysodeikticus, the first enzyme of serine biosynthesis, phosphoglyceric acid dehydrogenase, was found to be inhibited byL-serine, adenosine-5′-monophosphate (AMP), the reduced form of nicotinamide adenine dinucleotide, and less strongly by glycine. Inhibition by serine was increased by the incorporation of glycerol or divalent cations into cell-free extracts, and was decreased by ammonium sulfate fractionation. Inhibition by AMP was not modified by glycerol or ammonium sulfate fractionation but was increased by added divalent cations. The addition of Ca2+ions resulted in a greater increase in serine inhibition than Mg2+, Mn2+, or Zn2+ions. Serine and AMP inhibitions approached maxima in extracts containing about 30 mMCa2+. The synthesis of labeledL-phosphoserine from14C-3-phosphoglyceric acid was also inhibited by serine and AMP.

ISSN:0008-4166    

DOI:10.1139/m71-005

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

A bacterial contaminant from a cellulase-producing culture ofTrichurus cylindricuswas subjected to physiological and biochemical tests, and identified as a member of the genusMicrococcus, subgroup 6 (Baird-Parker). It appeared either to stimulate cellulase production by the fungus, or to increase cellulase activity. The amino acid and protein content of theMicrococcussuggested that it might be useful as a feed supplement. In a preliminary trial, rats accepted freeze-dried cells as a partial source of energy, and grew at a normal rate. No toxic effects of the diet were noted.

ISSN:0008-4166    

DOI:10.1139/m71-006

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The naphthylamidase isozyme complement ofSarcina luteawas studied. Gel filtration yielded two fractions, Sephadex I and Sephadex II. Sephadex I contained one enzyme generally resembling leucineaminopeptidase. Sephadex II, upon ion exchange chromatography, yielded three isozymes, A, B, and C. These three were characterized with respect to molecular weight, substrate specificities, and effects of hydrogen ion concentration, EDTA, and divalent cation on reaction velocity. The molecular weights are 8.0 × 104, 8.2 × 104, and 9.0 × 104respectively. Isozymes A and B are neutral naphthylamidases and preferentially catalyze the hydrolysis of alanine-β-naphthylamide (βNA), whereas isozyme C is a basic naphthylamidase and preferentially catalyzes the hydrolysis of lysine and arginine-βNA. The pH optima for the isozymes are 7.6, 7.6, and 6.7, respectively. All of the isozymes are sensitive to the effects of EDTA. Divalent cations activate the enzymes and reverse inhibition caused by EDTA.

ISSN:0008-4166    

DOI:10.1139/m71-007

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Using cell-free extracts ofNitrobacter agilis, we investigated the effects of CIPC and eptam on the oxidative phosphorylation coupled to nitrite oxidation as well as upon the reduced nicotinamide adenine dinucleotide (NADH2) oxidation to determine possible effects of the herbicides upon electron transport. Both CIPC and eptam exerted an uncoupling effect on the oxidative phosphorylation linked to nitrite oxidation. Although nitrite oxidation was inhibited, an intensely severe inhibition of phosphorylation caused a 50% reduction in the P/O ratio (μmoles of32P esterified per μatom of oxygen consumed) at about 2.3 × 10−4 MCIPC and at 8 × 10−4 Meptam. Likewise, 2,4-dinitrophenol (DNP), a classical phosphorylation uncoupler, affected the oxidative phosphorylation inN.agilis. Although oxygen uptake was inhibited, a 45% reduction in the P/O ratio occurred at 2.5 × 10−4 MDNP because of a greater effect on phosphate esterification. Neither CIPC nor eptam affected reduced nicotinamide adenine dinucleotide (NADH2) oxidase activity.

ISSN:0008-4166    

DOI:10.1139/m71-008

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Formation of the enzymes synthesizing 2,3-dihydroxybenzoic acid (DHB) inBacillus subtilisis repressed by iron. DHB does not appear to be involved in regulating its own biosynthesis. Hemin may be involved in regulating DHB synthesis. DHB synthetase is inhibited by severalm-substituted benzoic acids. The inhibitors do not affect the growth rate ofB.subtilisand DHB appears not to be necessary for growth under the conditions used. Inhibition of DHB synthesis during growth under iron-deficient conditions reduces the iron uptake capacity ofB.subtilis.

ISSN:0008-4166    

DOI:10.1139/m71-009

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Cells ofStreptococcus lactis(354/07) synthesized and retained nisin when grown in a complex medium with 2.5% glucose at a constant pH of 6.7. Nisin was extracted from cells by a previously used method with hot 0.05 NHCl but milder methods of extraction from whole and broken cells using a variety of solvents were also tested. In the preferred method broken cells were extracted with 0.05 NHCl at 2 °C. The Cl−ions of the extract were exchanged for acetate on columns of the resin Amberlite CG 4B and the eluate was concentrated by acetone precipitation at −19 °C. The nisin was finally purified by pH gradient elution from CM cellulose columns. Three peaks with antibiotic activity were found, two of the peaks were minor and represented less than 5% of the nisin. The main peak gave a single band on electrophoresis. Electrophoresis of the material from the CM cellulose peaks revealed about 44 bands of basic proteins. Nisin made by the hot or cold HCl extraction behaved similarly in electrophoresis and CM cellulose chromatography but the antibiotic activity of the material isolated from the cold extract was nine times greater than that of the material isolated from the hot extract.

ISSN:0008-4166    

DOI:10.1139/m71-010

出版商:NRC Research Press    

年代:1971

数据来源: NRC