摘要:

SUMMARY:Folpmers' glutamic acid medium and certain modifications of it have been compared with MacConkey's broth for the detection of organisms of the coli‐aerogenes group in water. Very satisfactory results were obtained with the glutamic acid medium made up in tubes and incubated in the same way as with MacConkey's broth. Less satisfactory acid were obtained when lactose was substituted for glucose in the glutamic acid medium, although both were superior to MacConkey's broth. The anaerobic method as described by Folpmers had too many disadvantages to be practicable for the routine examination of large numbers of sample

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1952.tb00001.x

出版商:Blackwell Publishing Ltd    

年代:1952

数据来源: WILEY

摘要:

SUMMARY:The heat resistance of a number of strains ofStreptococcus lactisandStr. faecalisat 60° in Ringer's solution and separated milk has been determined and the Decimal Reduction Times (D.R.T.) calculated.Heating in separated milk at 60° enabledStr. lactisto be sharply differentiated in most cases fromStr. faecalis.The latter gave D.R.T. values usually much above 3 min. while the former gave values usually under 1 min. and certainly less than 3 min. Single tests might give misleading results with certain strains.The log. survivor‐time graphs of both species were not always straight lines over all their length. A preliminary period of slow death was frequently obser

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1952.tb00002.x

出版商:Blackwell Publishing Ltd    

年代:1952

数据来源: WILEY

摘要:

SUMMARY:Certain aspects of the procedure for the nutritional classification of soil bacteria developed in this laboratory are discussed, particularly in the light of the criticism by Taylor (1951a). Though any system of nutritional grouping is admittedly susceptible to modifications as advances are made in our knowledge of bacterial nutrition, Taylor's criticism reveals, in part, a lack of understanding of the principles underlying various procedures; consequently certain objections are pointless. Possible merit in other points of objection is obscured by a lack of experimental data.Taylor's proposed scheme of classification indicates a different approach, based as it is on a study of cultures isolated from a more selective medium than ours, which latter was designed as being the least selective and one most favouring the ‘autochthonous’ soil bacteria. Furthermore, his method for assessing growth response in the differential liquid media appears to differ radically from ours. For the purpose for which our system of nutritional grouping was designed such changes are considered disadvantageous.Though Taylor is in agreement as to the need of certain strains of bacteria for some factor or factors present in soil extract, his attributing of a growth factor effect to the presence of calcium is open to objection in the absence of this element in the basal medium; the significance of the interaction between calcium and various peptones must now be interpreted in the light of the discovery of the role of vitamin B12in the nutrition of many soil bacte

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1952.tb00003.x

出版商:Blackwell Publishing Ltd    

年代:1952

数据来源: WILEY

摘要:

SUMMARY:Autoclaved sea water and water removed from the shell cavity of mussels supported the growth of coli‐aerogenes bacteria. Attempts to reproduce conditions which had favored multiplication of coli‐aerogenes bacteria in purified mussels failed.‘Enrichment’ of sea water by repeated re‐use for storage of successive lots of mussels, in conjunction with sand filtration and aeration under conditions equivalent to 60 weeks of approved purification, did not promote the growth of coli‐aerogenes bacteria.A culture ofSalmonella typhiandSalm. paratyphiB survived for a few days only in sea water favourable to the slow multiplication ofBacterium

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1952.tb00004.x

出版商:Blackwell Publishing Ltd    

年代:1952

数据来源: WILEY

摘要:

SUMMARY:The complexity of the action of certain phenolic bactericides on the metabolic activities of bacteria suggests that the interpretation of bactericidal action in terms of inhibition of a metabolic process may not always be justified. The action of cetyltrmethy lammonium bromide on the oxygen uptake ofBacterium colion several substrates appears to be straightforward and able to be correlated with viability studies.

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1952.tb00005.x

出版商:Blackwell Publishing Ltd    

年代:1952

数据来源: WILEY

摘要:

SUMMARY:Calcium alginate wool swabs were no more efficient or reliable than gauze or absorbent cotton wool swabs when tested on drinking glasses infected with known numbers of bacteria. The number of bacteria left on the glass after swabbing was determined by a modified roll tube method.

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1952.tb00006.x

出版商:Blackwell Publishing Ltd    

年代:1952

数据来源: WILEY

摘要:

SUMMARY:The numbers of coli‐aerogenes bacteria on ungrazed herbage and on intensively grazed pasture were determined by inoculation into MacConkey's broth incubated at 30°, 37° and 44°. From the cultures producing acid and gas at 30° organisms were isolated on eosin methylene blue agar and classified according to the recommendations of the Coliform Sub‐Committee. These micro‐organisms were abundant in grass from both habitats, and sometimes exceeded 107/g. The numbers were much lower at 37°, 80% of the samples of ungrazed herbage and 37% of those from grazed pasture containing less than 103/g.Bacterium coli, intermediate and aerogenes‐cloacae types were found with frequencies of 4, 19 and 77% respectively on ungrazed harbage, compared with 9, 17 and 73% on grazed pasture. Aerogenes‐cloacae types were dominant among the 37° positive cultures.A high proportion (53%) of the 249 classifiable cultures did not produce acid and gas in MacConkey's broth within 2 days at 37°. Anaerogenic and paracolon types at 30° were infrequent (5%) of ungrazed herbage, but constituted 18% of the classifiable cultures from grazed pasture. Unclassifiable cultures, mainly paracolons giving —–+ IMViC reactions and liquefying gelatin rapidly, were infrequent.There was no appreciable difference in the incidence of different types of coli‐aerogenes bacteria on flowering heads of grass examined during summer to that for the herbage samples examined throughout the year.Only 6 of the cultures picked from eosin methylene blue agar plates developed the golden‐yellow pigment on nutrient agar characteristic of the so‐calledBacterium herbicola, though lactose‐negative strains producing golden‐yellow or lemon‐yellow pigments were common in the ep

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1952.tb00007.x

出版商:Blackwell Publishing Ltd    

年代:1952

数据来源: WILEY

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1952.tb00008.x

出版商:Blackwell Publishing Ltd    

年代:1952

数据来源: WILEY

摘要:

SUMMARY:The rate of nitrification in mixed cultures was not affected by the simultaneous decomposition of cellulose. No stimultion of the rate of nitrification was observed in cultures containing: culture filtrates, soil extract, thiamin, yeast extract, urine, or β‐indolylacetic acid. These substances either had no effect or, in larger doses, delayed or stopped nitrification.Peptone was toxic to the nitrifying bacteria. Potassium chlorate did not affect the oxidation of ammonia to nitrite, but stopped the oxidation of nitrite to nitrate in cultures, as it does in soil. M/25 sodium fluorides stopped the oxidation of ammonia to nitri

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1952.tb00009.x

出版商:Blackwell Publishing Ltd    

年代:1952

数据来源: WILEY

摘要:

SUMMARY:Optimum conditions for the use of night blue and victoria blue as lipolysis indicators in fat emulsion agar medium required a dye strenth of 1: 15,000 in a medium of pH 8·0 containing 5% fat dispersed by hand shaking. Pour plates should contain 6 ml. and streak plates 10 ml. of the medium in a standard Petri dish. Incubation should be for 5 days at 30°. The pinkish‐mauve medium with clear blue‐zoned lipolytic colonies gave the same results as butter fat agar without dye but treated with CuSo4, when tested with 962 pure cultures. The inhibitory powers of the dye were assessed and although strongly toxic in the aqueous phase to Gram‐positive bacteria, victoria blue appears to have none to slight inhibitory power in the fat agar medium: night blue suppressed growth to about the same extent as tributyrin. The lipolytic flora of butter and to some extent milk shows a remarkable dominance of micorcocci. Organisms lipolytic on fat agar media are able to produce appreciable acid in a fat emulsion in a liquid

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1952.tb00010.x

出版商:Blackwell Publishing Ltd    

年代:1952

数据来源: WILEY