摘要:

A. SUEMORI, K. NAKAJIMA, R. KURANE AND Y. NAKAMURA. 1996.Rhodococcus erythropolisstrain S1 formed enzymes essential to the degradation of phthalate when grown in phthalate‐minimal medium. The reaction responsible for the dihydroxylation of the phthalate‐benzene ring was concluded to be catalysed by membrane‐associated phthalate 3,4‐dioxygenase (PO). Of the other enzymes involved, 3,4‐dihydro‐3,4‐dihydroxyphthalate 3,4‐dehydrogenase (PH) and 3,4‐dihydroxyphthalate 2‐decarboxylase (PC) appeared likely to be membrane‐bound, while protocatechuate 3,4‐dioxygenase appeared to be present in the cytoplasm. Based on the data, the membrane‐bound PO and PH apparently form an enzyme complex, which is associated with the

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1996.tb00016.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Nine strains ofPenicillium roquefortiisolated from a traditional Spanish blue cheese (Valdeón cheese) along with two commercial strains were investigated for their ability to grow at different concentrations of salt and at different temperatures as well as for their proteolytic and lipolytic activities. Low concentrations of salt (1‐3%) were stimulating for all the strains, with 1% salt being the concentration with the highest stimulating effect in nearly all. The rate of growth at 10°C was 2‐3 times lower than at 25°C, the optimum temperature for the species. None of the strains, including the commercial cultures, showed proteolytic activity on casein agar, while all of them were lipolytic on tributyri

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1996.tb00017.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Lean and adipose beef carcass tissues inoculated withBrochothrix thermosphacta (BT)(approx. 4.50 log10cfu cm−2) were left untreated (U) or treated with 100 μg ml−1nisin (N), calcium alginate (A) or 100 μg ml−1nisin immobilized in a calcium alginate gel (AN). Tissue samples were refrigerated after treatments and bacterial populations and nisin activity were determined at 0, 1, 2 and 7 d. U, A and N treatments of lean and adipose tissues did not suppress bacterial growth (>6 log10cfu cm−2by day 7) while treatments of lean and adipose tissues with AN suppressed bacteria (>2.42 log10cfu cm−2by day 7). Bacteriocin titres from both tissues were higher in ANvsN samples after the 7 d incubation. This study demonstrates that immobilization of nisin in a gel may be a more effective delivery system of a bacteriocin to the carcass surface than direct

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1996.tb00018.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

F.A. UZAL, J.J. PLUMB, L.L. BLACKALL, D. O'BOYLE AND W.R. KELLY. 1996. A polymerase chain reaction (PCR) was used to identify the gene‐encoding epsilon toxin production inClostridium perfringenstypes B and D in faeces and in gastrointestinal contents of goats. The samples were cultured in thioglycollate broth and centrifuged. The upper layer of the pellet was used as a template for PCR, obviating the need for DNA extraction. This technique specifically differentiatedCl. perfringenstypes B and D fromCl. perfringenstypes A and C and fromEscherichia coli. When used to identifyCl. perfringenstype D in samples artificially spiked with the micro‐organism, the PCR detected as few as 1.4 × 102cfu g−1of sample. Gastrointestinal contents and faeces were collected from 20 goats at slaughter and processed by PCR. Several positive results were obtained from the first five goats that were slaughtered and sampled a few days after their arrival at the abattoir, but only a few samples gave positive results during the following weeks, after the goats had been fed a concentrated ration containing monensin. A possible role of this drug in control of enterotoxaemia is sug

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1996.tb00019.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

s. BUNCIC AND S.M. AVERY. 1996. Three haemolytic, pathogenic strains ofListeria monocytogenes(a reference strain, a food‐derived strain and a human strain) were held at 4°C for 4 weeks in phosphate‐buffered saline pH 5.5 or 7.0, with and without 0.2% potassium sorbate or 0.3% sodium acetate. The number of viable cells did not change significantly during this storage. Pathogenicity of non‐growingL. monocytogenescells for 14‐d‐old chick embryos was determined before and after storage. Storage at 4°C resulted in decreased pathogenicity, but effects were strain‐, pH‐ and substrate‐dependent. After 4 weeks storage at 4°C non‐growing bacterial cells were transferred to Brain Heart Infusion broth and growth characteristics were determined during incubation at 37°C. Strains that showed decreased pathogenicity had significantly longer lag phases at 37°C than strains that maintained pathogenicity. It is concluded that decreased pathogenicity ofL. monocytogenesstored without growth at 4°C for 4 weeks and subsequent long lag phase

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1996.tb00020.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

N. SAKURAI AND S. KOMATSUBARA. 1996. Optimum conditions were determined for the electrotransformation ofSerratia marcescensSr41. The effects of electroporation buffers, growth conditions and electric field strength on transformation efficiency were examined. Under the optimal conditions established, the transformation efficiency was five orders of magnitude higher than that by the conventional CaCl2method. This method enabled use of plasmids prepared by the mini‐prep method. Freezing the cells in 100 g1−1glycerol and prolonged storage at −80°C did not affect the transformation effi

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1996.tb00021.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The effect of liquid mechanical vibration on the adhesion ofSaccharomyces cerevisiaecells to the internal glass surface of a pipette was studied using a 25 Hz vibration source. The maximum vibration amplitude was 1.06 mm (peak to peak) along the pipette direction. Relative movements between the pipette and yeast suspension in it were produced by vibration and reduced the cell adhesion. The reduction in adhesion was affected by both vibration amplitude and suspension pH. Analysis showed that in routine cell counts, cell adhesion to the pipette wall was a significant error source. The construction of a vibration device for routine cell count work appears feasible.

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1996.tb00022.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Conjugal transfer of plasmid pAMβ1 fromLactococcus lactisto intestinal bacteria of BALB/c mice was studied. Plasmid transfer was observed toEnterococcus faecalis in vitroby a filter mating method with transfer frequencies of 2.3 × 10−3and with lower frequencies to other species.In vivo, using gastric intubation with the pAMβ1‐bearingLactococcus lactisas donor andEnt. faecalisas recipient, a few transconjugants were detected from faecalEnt. faecalis. However, when these mice were given erythromycin through drinking water, a large number of conjugatedEnt. faecaliswere detected in faeces. Plasmid transfer toEnt. faecalisoccurred at high frequency, 1.2 × 10−3, in mice whose anus was artificially closed after gastric intubation with pAMβ1‐bearingLactococcus lactis. These results demonstrate clearly that pAMβ1 transfer occurs between Gram‐positive bacteria in the gut of mice harbouring many spec

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1996.tb00023.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

S. Solís, M.E. FLORES AND C. HUITRON. 1996. Protoplast release in pectinolytic strain mutants ofAspergillussp. CH‐Y‐1043 (A13) andAspergillus flavipesATCC‐16795 (F7) is described. Optimum yield of protoplasts A13 was obtained in a lapse of 1 h when commercially lytic enzymes ofTrichoderma harzanium(2 mg ml−1) were added in 0.05 mol 1−1citrate‐phosphate buffer pH 5.0 containing 0.7 mol 1−1KCl and 10 mg ml−1BSA. Best results in F7 were obtained when the protoplasting system of A13 was supplemented with 10 mg ml−1Aureobasidiumsp. lytic enzymes. Isolated protoplasts in A13 and F7 were capable of a high regeneration frequency of 87% and 53% when 0.7 mol 1−1KCl and sorbitol were used as osmotic stabilizers. Endo‐P, Exo‐P and pectin lyase production were not modified during the

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1996.tb00024.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Changes in the relative metabolism of soil bacteria and fungi following contamination with diesel were assessed using a modified substrate‐induced respiration (SIR) method including selective antibiotic inhibition.14CO2release from radiolabelled glucose was used as an indication of population activity. In a Sandy Gley Soil with no history of contamination, the population activity shifted from 38 ± 4% (bacterial): 62 ± 4% (fungal) to 73 ± 4% (bacterial): 27 ± 4% (fungal) after treatment with d

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1996.tb00025.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY