摘要:

Milk samples from 141 farms were plated on standard plate count agar and the colony count determined after incubation for 48 hours at 32 °C. Twenty colonies were picked at random from plates containing between 30 and 300 colonies. The isolates were inoculated into litmus milk and subsequently characterized on the basis of shape, Gram-staining reaction, catalase production, lactose fermentation, and the ability to form spores.Certain general trends in the flora were observed. In milk of a colony count less than 2 × 104per ml, micrococci were the dominant group of organisms, and as the colony count of the milk increased the percentage of micrococci decreased and the percentage of Gram-negative rods and streptococci usually increased. In spite of these general trends a study of the flora of individual samples showed that quite marked variations did occur.

ISSN:0008-4166    

DOI:10.1139/m66-063

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Growth studies ofNocardia erythropolis, an actinomycete described previously on cytological bases as reproducing by fragmentation, were carried out with cultures in liquid medium. Multiplication of this organism, indicated by viable counts, total cell counts expressed as particle production, and cell mass increase measured by optical density or cell volume increases, was significantly different from eubacterial multiplication. Two distinct phases were noted during the growth cycle. Active growth of the organism, as measured by cell mass, occurred early in the cycle in the absence of an increased viable count. Conversely, in the later phase of fragmentation, numbers of viable particles increased without a concomitant increase in cell mass. Toward the end of the phase of fragmentation the viability of the fragmentation product decreased markedly. It is postulated that nonviable fragments are in part a result of septum deposition which separates cytoplasmic elements of coenocytic filaments not containing nuclear elements.

ISSN:0008-4166    

DOI:10.1139/m66-064

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Endopolygalacturonase (endo-PG) synthesis was inducible in standing and replacement liquid culture byPyrenochaeta terrestris. Inducers were galacturonic acid, its polymers (pectin and polypectate), and structural relatives (mucic acid, tartronic acid, and dulcitol). On pectin, fungus growth and endo-PG synthesis were proportional to initial pectin concentration.Synthesis of endo-PG on pectin was stimulated by hexose supplements at 0.005 Mand repressed by supplements at 0.05 Mand above. Thus, repression of induced endo-PG synthesis was not dominant at low supplement concentrations as was found for induced cellulase synthesis by the same organism. This suggests that the production of endo-PG by the parasite during pathogenesis is less repressed by host sugars than is cellulase synthesis.

ISSN:0008-4166    

DOI:10.1139/m66-065

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Aspergillus amstelodamiwas grown on molasses medium to which was addedDL-tryptophan, labeled with14C in the 2 position of the indole ring or in the carboxyl, α, or methylene carbons of the alanine side chain. All of these labeled compounds were incorporated by the organism to a significant extent into echinulin. Carboxyl-14C-labeledDL-tryptophan was incorporated into echinulin without appreciable randomization of radioactivity. Methylene-14C-labeledL-tryptophan was used to a greater extent in the biosynthesis of echinulin than was theD-isomer. Both theD- andL-isomers were used more efficiently in the synthesis of fungal tryptophan than for the synthesis of echinulin.

ISSN:0008-4166    

DOI:10.1139/m66-066

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Ultra thin sections ofMicrococcus cryophiluscells were investigated. The cell wall, consisting of several layers, measures 410–500 Å and is covered with a distinct capsule. The cytoplasm, which is of granular structure, includes ribosomes, condensed chromatin, and occasionally mesosomes. The nuclear material has various shapes and is formed by filaments proceeding in various directions. We could find no evidence to bear out the supposition of Kocur and Martinec (1962) thatM.cryophilusis related toMicrococcus luteus.M.cryophilusis, in its structure as well as its groupings of cells, different from micrococci, which leads us to believe that it does not belong to the genusMicrococcus.

ISSN:0008-4166    

DOI:10.1139/m66-067

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Hyphal cell walls were prepared by ultrasonication. Glucose was the only sugar detected in both species. Evidence was obtained indicating that thePythium butleriSubram. glucan is beta 1,2-linked, and that the glucan ofPythium myriotylumDrechsler is beta 1,4-linked. Sixteen amino acids were detected inP.butlericell wall hydrolysates. Four of these amino acids were absent fromP.myriotylumpreparations. Similar quantities of lipid were found in both species. The significance of these data for fungal classification is discussed.

ISSN:0008-4166    

DOI:10.1139/m66-068

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

A method is described for studying the penetration of bacteria in intact rock cores. The test microorganism (Serratia marcescensATCC No. 274) was labelled with radioactive phosphorus (32P) and suspended in sterile demineralized water. The cell suspension was allowed to enter the epoxy-coated rock core under atmospheric pressure. Penetration and migration of the labelled microorganisms were followed by measuring the radiation emitted at ports drilled through the epoxy coating, at various locations throughout the length of the core, and at various intervals of time after the beginning of the experiment. When migration was considered to be complete the core was aseptically split longitudinally and the results of the radiation studies confirmed by autoradiogram and culture.S.marcescenspassed through 14.25 in. of Berea sandstone (the longest core available), and through 3-in. cores (longest available) of Mississippian limestone, Early Devonian limestone, and Late Mesozoic sandstone. The significance of these findings is discussed with respect to presence of so-called prehistoric microorganisms in geological specimens.

ISSN:0008-4166    

DOI:10.1139/m66-069

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Cross-agglutination tests with sera obtained by injection of vegetative cells, asci, and spores into rabbits revealed no immunological distinction between the walls of vegetative cells and asci, whereas the spore coats were found to be serologically distinct from cell and ascus walls. Treatment of vegetative cells and asci with periodate or a proteolytic enzyme before agglutination tests gave results which suggest that the critical antigen is a protein structure.

ISSN:0008-4166    

DOI:10.1139/m66-070

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Unisexual forms of certainTremellaspecies produce extracellular acidic heteropolysaccharides when grown on media containing glucose. The isolated polysaccharides contain the same components found in polymers produced by strains ofCryptococcus laurentii, i.e.,D-glucuronic acid,D-xylose,D-mannose, and O-acetyl. Optical rotations and molar ratios of components were determined. The polysaccharides are characteristic of the various species ofTremellawhich produce them. Some of these species produce polymers that contain much higher proportions of xylose than are found in the polymers produced byC.laurentii. Those tremellae that produce polymers resemblingC.laurentiipolysaccharides also give similar carbon assimilation patterns, but tremellae that produce polymers of higher xylose content also assimilate fewer carbon compounds. These findings, together with similarities in starch synthesis and morphology, suggest a relationship between some species ofTremellaandCryptococcus.

ISSN:0008-4166    

DOI:10.1139/m66-071

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The composition of an extracellular heteropolysaccharide fromTremella mesentericaFries NRRL Y-6151 (O-acetyl:xylose:mannose:glucuronic acid molar ratio 0.5:4.4:3.8:1) was investigated by examination of partial acid hydrolysis products. Removal ofD-xylose residues by mild hydrolysis gave a polymer containing xylose:mannose:glucuronic acid in a molar ratio of 2.8:3.6:1. More extensive hydrolysis led to the formation of oligosaccharides containing mannosyl units appended to 2-O-(β-D-glucopyranosyluronic acid)-D-mannose.

ISSN:0008-4166    

DOI:10.1139/m66-072

出版商:NRC Research Press    

年代:1966

数据来源: NRC