摘要:

SUMMARY:Sodium sulphide or cysteine stimulated the growth of sulphate‐reducing bacteria; small populations often did not grow without such supplements. Ascorbic acid, glutathione or thiolacetic acid had similar properties but thiolacetic acid was sometimes inhibitory, Dilution counts in liquid media or colony counts in agar media did not bear any regular relation to the total count unless one of these supplements was present. With suitable precautions colony counts reaching 50 to 60% of the total count were obtained in media incorporating cysteine and a ferrous salt (as an indicator of sulphide formation).Samples of natural origin containing sulphate‐reducing bacteria gave greater viable counts in cysteine‐iron media than in unsupplemented media. Blackend culture tubes with natural populations were sometimes due to cysteine‐decomposing organisms; further examination of positive tubes was therefore ne

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1953.tb00020.x

出版商:Blackwell Publishing Ltd    

年代:1953

数据来源: WILEY

摘要:

SUMMARY:In outbreaks of food poisoning from meat, caused bySalmonellaorganisms, intravital infection and post‐mortem contamination of the meat must be distinguished. Man and different species of animals suffering fromSalmonellainfection may be a source of infection or contamination. In the Netherlands this is especially the case with carriers ofSalm. dublinin adult cattle. In the National Salmonella Centre, 41Salmonellatypes were isolated from man and animals in the years 1946–1952. In 1949–1952, eighteen outbreaks of food poisoning due to meat products and only one due to fresh meat were examined. In 4 cases an intravital infection of the meat was established; in the remaining cases the source of contamination remained unknown. The causative types were:Salm. dublin, Salm. typhi‐murium, Salm. paratyphiB,Salm. oregon, Salm. newportandSalm. bovis‐mo

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1953.tb00021.x

出版商:Blackwell Publishing Ltd    

年代:1953

数据来源: WILEY

摘要:

SUMMARY:Roll‐tube colony counts, using the Astell equipment, were lower than the corresponding Petri dish counts with 27 out of 31 raw milks (87%). The difference between the counts by the two methods was greater than 25% of the plate count for 12 (39%) of the samples.When the same dilution of milk was used for both strip‐tube and plate colony counts, about equal numbers of samples gave counts from the strip tubes above and below about the colony count from plates. When, in order to obtain a more reasonable strip‐tube count, the plates and strip tubes were prepared from different dilutions of the milk, the counts from the latter were, with only 3 exceptions out of 35 milks, below those from the former. The difference between the counts was greater than 25% of the plate count for 15 (43%) of the milks, a figure similar to that obtained in comparing roll‐tube and plate colony

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1953.tb00022.x

出版商:Blackwell Publishing Ltd    

年代:1953

数据来源: WILEY

摘要:

SUMMARY:Incubation at 30° and 37° for the presumptive coli‐aerogenes test for raw and pasterurized milk has been investigated. There were more positives at the lower temperature and it is suggested that in this test, incubation at 30° might provide a much better guide to the hygienic quality of both raw and pasterurized milk. The ability of the coli‐aerogenes bacteria studied to ferment lactose in MacConkey's broth at 30° but not at 37° was found to be a stable factor which was unchanged by prolonged storage on agar slopes at room temperature or on continued incubation in MacConkey's broth at temperatures above the optimum for lactose ferm

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1953.tb00023.x

出版商:Blackwell Publishing Ltd    

年代:1953

数据来源: WILEY

摘要:

SUMMARY:An examination of green crops has indicated that the counts of lactobacilli may not always be sufficiently high to ensure preservation when the fodder is made into silage.

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1953.tb00024.x

出版商:Blackwell Publishing Ltd    

年代:1953

数据来源: WILEY

摘要:

SUMMARY:Farm water supplies giving 37° positives in MacConkey's broth within 24 hr. had a much higher incidence of presumptiveBact. colitype I than those which gave 37° positives during the second day of incubation only; presumptiveBact. colireactions were obtained with 85% of the 7,522 tubes positive in 24 hr. compared with 23% for the 7,593 tubes showing positive reactions during the second day at 37

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1953.tb00025.x

出版商:Blackwell Publishing Ltd    

年代:1953

数据来源: WILEY

摘要:

SUMMARY:A chemically defined glucose ammonium phosphate medium gave methy red and Voges‐Proskauer reactions which were superior to those in glucose peptone phosphate. Optimum condition for both tests require a starting pH of 6·8 and incubation for 3 days at 30°. The medium gave a negative correlation between the two reactions with 34 out of 35 strains that were positive to both tests in the peptone medium. The addition of glutamic acid helped to eliminate doubtful positive M. R. reactions but seemed to suppress acetylmethylcarbinol production by weakly V.‐P. positive st

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1953.tb00026.x

出版商:Blackwell Publishing Ltd    

年代:1953

数据来源: WILEY

摘要:

SUMMARY:The bacteria in the slime are capsulated and withstand drying longer than the non‐capsulated from derived from cultures. The natural slime is either neutral or slightly alkaline in reaction but turns acid when kept under humid conditions; it contains available nutrients, a toxic substance and two pectic enzymes.Certain substances belonging to the classes of compound detected in natural slime were tested to see whether they would increase the infectivity of the bacteria, and it was found that glutamine and asparagine caused a considerable increase. Cultures of the pathogen 10 weeks old contained a wilt producing toxin which also apparently increased the infectivity. Inoculation of acidified suspensions reduced infectivity. Typical cankers were not produced by adding nutrients to bacteria inoculated into popular twigs. The slime provides a particularly suitable substrate possessing the optimum requirements for infectio

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1953.tb00027.x

出版商:Blackwell Publishing Ltd    

年代:1953

数据来源: WILEY

摘要:

SUMMARY:A process for dehydrating fish under vacuum and in contact with heated plates is described. Although the conditions, in respect of time and temperature, appeared suitable for microbial development, a reduction in the number of bacteria usually occurred. A survey of the data accumulated over twenty months, including a series of experimental production periods, showed that the bacterial population estimated at 22° was reduced in the process as a whole to about 1% of its initial value and that estimated at 37° to about 10%. Species of the genusMicrococcustended to predominate on the finished product. Contrary to earlier expectations, there should be no serious microbiological hazards if high standards of personal and factory hygiene are maintaine

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1953.tb00028.x

出版商:Blackwell Publishing Ltd    

年代:1953

数据来源: WILEY

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1953.tb00029.x

出版商:Blackwell Publishing Ltd    

年代:1953

数据来源: WILEY