摘要:

Summary:During a period of four years the keeping quality of milk commercially sterilized by a continuous automatic process has been recorded. The results indicate a marked seasonal variation, suggesting a relatively high incidence of aerobic spore‐formers in winter milk and a relatively low incidence in summer milk. Aerial contamination from dusty fodders is tentatively suggested as the dominant factor controlling this phenomeno

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1954.tb02016.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

Summary:A microaerophilic plectridium identified asClostridium pectinovorum, andCl. butyricum, were the major sporulating organisms found on English flax. Both these organisms were non‐pectolytic and unable to ret flax. An orange pigmented anaerobe, identified asCl. aurantibutyricum, was found as a minor organism, occurring on some samples only. This organism was remarkably pectolytic and an active retting agent.Bacillus polymyxa, which attacks pectin and is a moderately active retting agent in aerobic and anaerobic rets, was occasionally found.Cl. tertium, which has been reported on English flax and in flax rets, and is regarded as an active retting agent in aerated and non‐aerated rets, proved to be non‐pectolytic and showed no retting ability. It was identical withCl. pectino

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1954.tb02017.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

Summary:A platinum cylinder is described which is capable of dispensing aseptically volumes of about 001 ml. with an error of less than ±10%. In special cases the errors rarely exceed ±1

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1954.tb02018.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

Summary:A medium permitting consistently good growth of known strains of lactobacilli was determined using nineteen strains considered difficult to grow. For the culture media tested various concentrations of albumin, starch, Tween 80, sodium oleate and Yeastrel were added to tomato dextrose broth and strain growth was measured by a photo‐electric absorptiometer. Statistical analysis showed that, of the combinations tested, the best response was achieved by the addition to tomato dextrose broth of Tween 80 (0.1% v/v) and Yeastrel (0–6% w/v) with or without 0.5% of sta

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1954.tb02019.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

Summary:Media have been sterilized by continuous flow through a heat exchanger and holding tank in shorter time at a given temperature than by conventional batchwise sterilization. Economies of steam and cooling water were obtained, and the less drastic heating minimized changes in the media, giving higher penicillin titres.

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1954.tb02020.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

Summary:A study has been made of the use of triphenyltetrazolium bromide as an indicator of bacterial dehydrogenase activity. It has been shown that for practical purposes the determination may be carried out in the presence of air, thus obviating the use of oxygen‐freed Thunberg tubes. The method has been placed on a quantitative basis by determining, colorimetrically, the formazan produced on reduction. The limitations of the method are discusse

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1954.tb02021.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

Summary:Seven species of bacteria, including both rods and cocci, were exposed in dilute suspension in solutions of dried skim milk and in nutrient broth to ultrasonic vibrations of 1 Mc./s. frequency.Bacterium coli, Lactobacillus caseiand aMicrobacteriumspecies were killed fairly rapidly,Bact. colibeing the most sensitive.Staphylococcus aureus, Streptococcus lactis, Strep, faecalisandStrep, pyogenesshowed at first a rise in the viable count, followed by a decline in numbers. The cocci were all more resistant than the rod‐shaped species tested. Similar tests at 20.5 Kc./s., but with much less power absorbed, showed a slower decline in numbers withBact. colithan at 1 Mc./s. There was no decrease withStaph, aureus, but there was more rapid death ofStrep, lactisduring the second half of the treatment period. In relation to power absorbed, the lower frequency was the more effective.Under conditions which caused rapid death ofBact. colisuspended in broth, complete protection was afforded to that organism by fresh whole milk: smaller degrees of protection were seen in both homogenized and separated milk. Protection was also conferred by dried skim milk, casein, gelatine and peptone in solution, the effect increasing with concentration. High concentrations of lactose and gum tragacanth also had some effect.WhenBact. coliwas treated at 1 Mc./s. in broth, there was no lethal action unless the power absorbed exceeded a quite large threshold value: no threshold was detected at the lower frequency.The death rate ofBact. colitreated at 1 Mc./s. in various liquids was as a rule not constant: it usually diminished with time. The shape of the survivor curve was greatly altered when the volume (depth) of suspension treated was increase

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1954.tb02022.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

Summary:Chemical changes resulting from microbial growth in a simple medium containing glucose as the only source of carbon, and ammonia as the only source of nitrogen, depended not only upon the concentration of nutrient materials and the rate of supply of air, but on the shape and size of the container, the depth of liquid and the method of aeration. If, by the time all the glucose was destroyed, the pH value had not fallen below about 3.0, continued aeration resulted in a substantial rise in pH value, due to oxidation to carbon dioxide of organic acids formed in the earlier stages.Initial growth in a simple medium was suppressed not only by aeration of a pure culture with a current of CO2‐free air, but also by violent aeration of a mixed culture with air with a normal content of carbon dioxide.Changes occurring in a complex organic medium, a sterile extract of red beet, were similar in character to those observed in the simple medium, but were much less affected by irregularities in growt

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1954.tb02023.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1954.tb02024.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1954.tb02025.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY