Journal of Applied Microbiology

BARR, J. G.

doi: 10.1111/j.1365-2672.1975.tb00539.xpmid: 809403

Ten antimicrobial metabolites, produced by Bacillus subtilis NCIB 8872, have been categorized into 3 groups on the basis of their antimicrobial spectra, chromatographic mobility and solvent solubility. The maximum concentration of the different groups occurred at different times during fermentation. The accumulation of one antibiotic group was characteristic of the logarithmic growth phase. Groups also differed in their persistence. The intracellular antibiotics contributed little to the total antibiotic activity of the culture. The onset of production and the maintenance of the extracellular accumulation of the 3 antibiotic groups were linked to sporulation and associated specific changes in the intracellular and extracellular protein complement. Production of the antibiotics was not controlled by glucose catabolite repression, since the presence or absence of glucose in the medium did not affect the pattern of antibiotic accumulation.

MOSSEL, D. A. A.; VEGA, CLARA L.; PUT, HENRIETTE M. C.

doi: 10.1111/j.1365-2672.1975.tb00540.xpmid: 1165225

Oxytetracycline–glucose–yeast extract agar (OGYA), gentamicin–glucose–yeast extract agar (GGYA) with the antibiotic added separately or sterilized with the medium, chlortetracycline–Rose Bengal agar (CRA), chloramphenicol‐streptomycin agar (PYA) and to a lesser extent, oxytetracycline–gentamicin–glucose–yeast extract agar (OGGYA) with or without Rose Bengal added, have been compared for the selective enumeration of moulds in foods. The results obtained from dried cereal products show that the media are almost equally productive and selective when applied to such foods, but Rose Bengal limits the size of mould colonies. When examining fresh proteinaceous foods, such as minced meat and chicken, CR agars and to a certain extent gentamicin‐containing agars show the distinct advantage of being much more inhibitory towards the psychrotrophic Gram negative rods that predominate in the associated flora of such foods. Oxytetracycline–glucose–yeast extract agar lost its bacteriostatic properties when heavily challenged with proteinaceous substrates and/or incubated for longer periods at 37° or even at 25°. For such applications chloramphenicol was found to be the antibiotic of choice.

OWENS, J. J.; JOHN, P. C. L.

doi: 10.1111/j.1365-2672.1975.tb00541.xpmid: 1172500

The composition of egg yolk media is important for the identification of egg yolk positive strains of coagulase positive staphylococci. Media with glucose allowed the detection of more egg yolk positive strains than those without it. However, the presence of 50% CO2 in the incubation atmosphere allowed a greater number of egg yolk positive strains to be detected regardless of whether glucose was present or not. This was due to the suppression of lipase activity by CO2 thus allowing total lipid separation indicative of the egg yolk phenomenon. Staphylococcus aureus strains from human nares were egg yolk positive and strongly lipolytic while strains of animal origin and epidermal necrolysis were egg yolk negative and weakly lipolytic.

AHMED, F. I. K.; RUSSELL, C.

doi: 10.1111/j.1365-2672.1975.tb00542.xpmid: 1100579

The lethal effect on different micro‐organisms of ultrasonic waves and hydrogen peroxide separately and in combination was examined. Ultrasonic waves were able to disintegrate Fusobacterium nucleatum within 3 min and to kill Veillonella parvula after 15 min and Streptoccus sanguis after 20 min; 20 vols H2O2 (6% w/v) killed V. parvula, Strep. sanguis and Staphylococcus aureus after 5 min treatment, and Clostridium sporogenes spores after 25 min. Sonication of Cl. sporogenes spores, Bacillus cereus spores and Candida albicans in 20 vols H2O2, using an ultrasonic probe, was lethal to the organisms after 15, 10 and 10 min, respectively. The latter 2 organisms were not killed by 30 min exposure to either agent separately. Similar results were obtained when an ultrasonic tank was used for sonication.

STOTT, J. A.; HODGSON, J. E.; CHANEY, JANE C.

doi: 10.1111/j.1365-2672.1975.tb00543.xpmid: 1172501

During a survey of meat and bone meals, fish meals and poultry feeds salmonellae were found only in samples of meat and bone meal, for which 19% were Salmonella‐positive. MPN estimations on 2 meat and bone meal samples gave figures of 6 and 39 salmonellae/ 100 g, respectively. Sampling of poultry feed before and after pelleting showed that this process gave up to 1000‐fold reduction in numbers of Enterobacteriaceae depending on the type of processing involved.

GRAY, E. A.

doi: 10.1111/j.1365-2672.1975.tb00544.xpmid: 1100580

During a study of the survival of Escherichia coli in a chalk stream and in the laboratory, the organism ceased to grow in filtered stream water if air free of atmospheric carbon dioxide was passed over the culture. Fewer E. coli cells grew with the alga Stichococcus bacillaris in the light than in the dark. In the stream, low numbers of the organism were associated with plant blooms (macrophytes and microphytes). It is suggested that the numbers of E. coli in natural waters may sometimes be determined by the content of dissolved carbon dioxide which itself must be affected by the volume of photosynthesizing green cells.

NOTERMANS, S.; KAMPELMACHER, E. H.; VAN SCHOTHORST, M.

doi: 10.1111/j.1365-2672.1975.tb00545.xpmid: 1100581

Contamination which occurs at an early stage in the poultry processing line is estimated less accurately by the ‘skin‐dip’ method than by the ‘skin‐maceration’ method. From the results obtained during these studies it is also evident that the bacterial count determined by the method of rinsing the whole carcass cannot be related to counts determined using the skin maceration method.

JONES, J. G.

doi: 10.1111/j.1365-2672.1975.tb00546.xpmid: 1165226

A study of iron bacteria in the hypolimnion of Blelham Tarn and 2 large experimental tubes therein showed that counts of Leptothrix ochracea filaments were proportional to total iron concentration. A regression equation was derived which described the relationship and from which 95% prediction limits of the counts could be obtained. This equation, however, failed to account for a significant proportion of the variability of the bacterial counts, nor could this be explained by changes in the other variables measured. Possible sources of variation are noted, as are results from a vertical profile from another productive lake and the reasons for the occurrence of significantly larger numbers of Leptothrix filaments in one of the enclosures. Changes in the appearance of the sheath of L. ochracea and the capsules of other iron bacteria with a similar distribution pattern, occurred when O2 was absent from some samples.

DAINTY, R. H.; SHAW, B. G.; DE BOER, KLASKA A.; SCHEPS, ELLY S. J.

doi: 10.1111/j.1365-2672.1975.tb00547.xpmid: 240792

Proteolysis could not be detected, prior to the appearance of spoilage odours and surface slime, in beef allowed to spoil aerobically at 5° with its own natural flora or after inoculation with a reconstituted freeze‐dried beef slime. Although the slime inoculum gave a final microbial flora similar to the naturally‐attained one, it resulted in more rapid and extensive post‐spoilage proteolysis. Pure culture experiments showed that proteolysis was probably due to the activities of Gram negative organisms.

doi: 10.1111/j.1365-2672.1975.tb00548.xpmid: N/A

Mycotoxins (1974). Edited by I. F. H. Purchase.