ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1977.tb00717.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Meat of high pH value (6·6) showing dark‐cutting characteristics was vacuum‐packaged and stored for up to 8 weeks at 0–2°C. ‘Off’‐odours were detected on opening the packages after 6 weeks of storage. Total counts at this stage wereca.107/cm2of which lactobacilli were the major component, withca.106/cm2Gram negative organisms. PsychrotrophicEnterobacteriaceaerepresented a major proportion of the microflora only after the full 8 weeks of storage and were not detected previously. Aerobic storage of steaks cut from the vacuum packaged meat stored for 8 weeks resulted in a predominantly Gram negative spoilage flora.Inoculation studies on meat of normal pH value (5·4) and appearance using representative isolates from the vacuum‐packaged meat microflora indicated that most of the test organisms were capable of causing spoilage under aerobic conditions but few under vacuum‐packaging when incubated at 4°C. On meat of higher pH value (6·15) many of the Gram negative isolates did not grow as well, whereas the Gram positive isolates grew better than on meat of normal pH value when held under aerobic conditions. Under vacuum‐packaging all but one isolate grew as well or better on meat of high pH value than on normal meat at 4°C and objectionable

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1977.tb00718.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Responses of the soil microflora to the herbicide dalapon have been examined using three different soil treatments. The parameters examined were bacterial numbers and dehydrogenase activity. The effects of dalapon were less marked in soil cores sprayed with dalapon than in disturbed soil samples with herbicide incorporated throughout. Air‐drying of soil reduced the rate of disappearance of dalapon. The implications of these results are discussed in relation to the problems of designing sensitive tests which avoid exaggerated or abnormal effects of the agricultural chemical under tes

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1977.tb00719.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Two media, one for enrichment and the other for differentiation ofListeria monocytogenes, are described and a method is proposed for the selective isolation of this bacterium from material containing a mixed bacterial flora such as faeces, vaginal swabs etc. Addition of potassium dichromate, chromium trioxide, thionin, nalidixic acid and amphotericin B to Todd‐Hewitt Broth (BBL) made a satisfactory enrichment broth in which good selective growth ofL. monocytogeneswas obtained without notable damage to cells. The differentiation agar was Trypticase Soy Agar (BBL) supplemented with gallocyanin, pyronin and nalidixic acid. On this mediumL. monocytogenescolonies, when viewed by the Henry's oblique transillumination technique, were blue in contrast to colonies of other bacterial species which were pink or red. Trials with experimentally infected materials showed thatL. monocytogenescould be recovered from faeces infected with as few as 20L. monocytogenescells/g. All common contaminants, with the exception of a few strains ofStreptococcus faecalis, were inhibite

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1977.tb00720.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The effect of different gaseous atmospheres on the development of the bacterial flora on lamb chops stored at –1°C was examined. The atmospheres were air, nitrogen, hydrogen, and mixtures of air + carbon dioxide, oxygen + nitrogen, oxygen + carbon dioxide, nitrogen + carbon dioxide and hydrogen + carbon dioxide (gas ratio = 80:20, v/v). Storage life of chops ranged from two weeks in air to eight weeks in oxygen‐free atmospheres. At the end of storage lifeMicrobacterium thermosphactumwas present as a major constituent of the bacterial flora in all atmospheres. In oxygen + carbon dioxide it was the predominant organism. In all other oxygen containing atmospheres,Pseudomonasspp. made up a large proportion of the flora. Strains of Enterobacteriaceae occurred in low‐oxygen and oxygen‐free atmospheres, andLactobacillusspp. occurred in oxygen‐free a

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1977.tb00721.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Recent point source microbiological studies, using radial grid sampling stations, have indicated the potential of using bacterial populations to delineate mixing zones and identify the plumes. The discharge from the Niagara River into Lake Ontario was studied and microbiological data from the main plume area (impact zone), zone of minor influence of the plume, and the non‐plume lake waters are presented. The microbiological observations were found to agree with thermal observations of the plume area made by remote sensing scanning technique

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1977.tb00722.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Entodinium longinucleatumgrownin vitroin the presence of bacteria engulfed a wide range of bacterial species at rates of 130–3400 bacteria/h/protozoon (from suspensions of 10 bacteria/ml), but showed a preference forKlebsiella aerogenesandProteus mirabiliswhich occurred in the growth medium. Some of the bacteria were digested with release of soluble material into the medium. Free amino acids were incorporated by the protozoa in the presence of chloramphenicol at rates of 5·4–15·1 nmol/h/106protozoa and approximately 40% of the amino acid‐carbon was incorporated into protein. There was no appreciable synthesis of protozoal protein from carbohydrate. Evidence was obtained that the protozoa obtained the amino acids required for growth largely from engulfed b

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1977.tb00723.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

It has been demonstrated, using immunocytochemical techniques, that individual spore antigens are synthesized in discrete compartments of the bacterial cell. An outer layer of bacterial spores, demonstrable ultrastructurally as a distinct exosporium inBacillus cereusor as an outer tight‐fitting sporecoat inB. subtilis, is synthesized in the cytoplasm of the mother cell. Conversely, the layers of the inner sporecoat antigens are synthesized in the forespore compartment and in association with the forespore membranes. Different layers of the sporecoat are thus synthesized in separate morphological areas and are presumably under different genetic control. Immunocytochemical techniques indicate that dipicolinic acid is found in association with the sporecor

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1977.tb00724.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Fungistatic data were obtained from measurements of mycelial growth of several fungal species in the presence of acid or alkaline glutaraldehyde. Alkaline glutaraldehyde in concentrations>0·1% (w/v) prevented growth of all species examined while 0·5% (w/v) acid glutaraldehyde was necessary to achieve this effect. Further fungistatic data were obtained using a Coulter Counter method to measure spore swelling. Fungicidal determinations resulted in a 99·99% reduction in viable count after 90 min contact with 0·5% (w/v) alkaline glutaraldehyde. A considerable drop in spore production was also observed after treatment with alkaline glutaraldeh

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1977.tb00725.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The ability of agrobacteria to reduce Nile Blue more strongly than do rhizobia is the basis of a test for separating these two groups (Hamdi 1969). In a modified test using only 35 parts 10° of Nile Blue in the medium, 89 of 90 rhizobia (Rhizobium japonicum, R. leguminosarum, R. lupini, R. phaseoli, R. trifolii, cowpea, groundnut andLotusrhizobia) failed to reduce the dye whereas all 24 strains of agrobacteria (Agrobacterium radiobactervar.radiobacter, A. r.var.tumefaciensandA. r.var.rhizogenes) reduced it to the colourless state. Only oneRhizobiumstrain formed 3‐ketolactose from lactose, but 13 agrobacteria produced it.Rhizobium melilotistrains (12) gave variable reactions in both tests. The Nile Blue Test detected rapidly, but not slowly growing, strains of agrobacteria present as contaminants of rhizobia cultures even when their initial numbers were sma

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1977.tb00726.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY