摘要:

Using the cellulose-film method the distribution of mycostasis was examined in profiles from five differing soil types in Malaya. Soils were found to be inhibitory to the spores ofMucor ramannianusMöller to a depth of 360 cm, but waterlogged soils were less inhibitory than those which were drained. The addition of 1% (w/v) glucose only partially masked the inhibition in some soils while autoclaving the soils before assay resulted in a complete removal of the inhibition from the upper soil layers only. It was suggested that the mycostatic factor produced in the soil as a result of biological activity only extends down to a depth of 120–150 cm, whereas deeper layers in the profile possess an inhibitory factor which is non-biological in nature. The pattern of soil mycostasis was compared with those established for Nigerian and British soils and it was concluded that the pattern in Malayan soils resembled more closely that from Britain.

ISSN:0008-4166    

DOI:10.1139/m66-021

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Three hundred cultures of yeasts and yeast-like fungi were tested for their ability to metabolize flavonoid compounds. Rutin, quercitrin, taxifolin, and naringin were used by strains ofPullulariaand by the asporogenous yeastsCryptococcus albidusandCryptococcus diffluens. Catechin and 5, 7-dihydroxyiso-flavone were not used by any of the cultures tested.The utilization of flavonoid compounds was dependent upon the nutritional complexity of the medium used. When a complex organic nitrogen source was used in the medium, not only were quercetin glycosides metabolized at a faster rate but yeasts, which were inactive on a synthetic medium, utilized varying amounts of the glycosides. The aglycone quercetin was utilized only in the presence of organic nitrogen compounds. Culture filtrates were inactive but cell-free extracts of aPullulariasp. and of strains ofC.albidusandC.diffluensdegraded rutin, in the presence of air, to glucose, rhamnose, protocatechuic acid, phloroglucinol carboxylic acid, and carbon monoxide. The metabolism of flavonol glycosides by yeasts is discussed as a taxonomic characteristic and the pathway used is compared to the known microbiological routes for the utilization of these compounds.

ISSN:0008-4166    

DOI:10.1139/m66-022

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

A method is described employing14CO2uptake by the marine centric diatomCyclotella nana(clone 13-1) for the bioassay of vitamin B12in seawater. Seawater samples were filter sterilized, supplemented with sterile medium constituents, and diluted with a similarly supplemented, charcoal-treated filtered seawater. Samples or diluted samples, internal standards, and external standards were inoculated with the diatom such that the initial concentration of cells was approximately 1 × 104per milliliter. The bioassay flasks were incubated for 47 hours,14C as Na214CO2was added, and14C assimilation was measured after a 2-hour exposure. The rate of uptake of14C could be related to B12concentrations when these were in the range of 0.05 to 3.0 μμg B12per milliliter. A 49-hour incubation time was selected since cells required time to adapt to seawaters collected from different locations. The concentration of B12in a seawater sample was calculated from the radiocarbon uptake, the percentage of the internal standard recovered, and the dilution factor. The method is more sensitive than that described by Gold from which it was derived, and takes into account the serious inhibitory effects found in many samples of natural seawater. The limit of sure detection is about 0.05 μμg B12per ml and the standard deviation of the method was about 0.3 μμg per ml when measuring 1.4 μμg B12per ml in inhibitory seawater.

ISSN:0008-4166    

DOI:10.1139/m66-023

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Cultures ofEscherichia colisubjected to various treatments were studied for their viability loss, as well as for the changes in fluorescent response on staining with the fluorochrome acridine orange. The treatments employed were irradiation with gamma rays (two different dose rates), beta rays, and ultraviolet rays; thermal shock; thymine starvation; and streptomycin inhibition. Marked deviations from "Strugger effect" are seen. The differences in response observed at different dose rates of irradiation are discussed.

ISSN:0008-4166    

DOI:10.1139/m66-024

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

A two-step procedure in which a new anaerobic liquid medium is used for a presumptive test and a solid medium (staphylococcus medium No, 110 fortified with egg yolk) incubated at 45 °C for a confirmatory test has been developed for the detection and enumeration of coagulase-positive staphylococci in frozen seafoods. The presumptive liquid medium called "Mannitol Salt Sorbic acid broth" provides specific enrichment to coagulase-positive staphylococci even in the presence of large numbers (104–105cells) of mixed flora common to these foods. The addition of seafood material to the above medium does not affect its selective performance or its sensitivity. Also, the medium is equally efficient in recovering very low numbers of coagulase-positive staphylococcus subjected to freezing, even in the presence of the mixed flora. Incubation at 45 °C in the confirmatory step not only gives an accelerated egg yolk precipitation reaction typical of coagulase-positive staphylococci, but also enhances the specificity of the procedure.

ISSN:0008-4166    

DOI:10.1139/m66-025

出版商:NRC Research Press    

年代:1966

数据来源: NRC

ISSN:0008-4166    

DOI:10.1139/m66-026

出版商:NRC Research Press    

年代:1966

数据来源: NRC

ISSN:0008-4166    

DOI:10.1139/m66-027

出版商:NRC Research Press    

年代:1966

数据来源: NRC

ISSN:0008-4166    

DOI:10.1139/m66-028

出版商:NRC Research Press    

年代:1966

数据来源: NRC

ISSN:0008-4166    

DOI:10.1139/m66-029

出版商:NRC Research Press    

年代:1966

数据来源: NRC