ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1991.tb03778.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1991.tb03779.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1991.tb03780.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Cultures ofErwinia carotovorasubsp.atroseptica, grown at 27°C and 30·°C in different liquid media were assayed for activities of pectate lyase, polygalacturonase and cellulase. Total production of both pectate lyase and of polygalacturonase was 3–6 times less at 30·5°C than at 27°C; secretion of pectatelyasewas similarly affected. Cellulase was cell bound and its production was not affected by the temperatures investigated. Growth, protein synthesis and protease activity were similar at the two temperatures and production of enzyme activity at 27°C and 30·5°C was independent of the gro

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1991.tb03781.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The peptide, pediocin AcH, fromPediococcus acidilacticiH binds to the cell surface ofLactobacillus plantarumNCDO 955, its resistant mutant and several other sensitive and resistant Gram‐positive bacteria but not to Gram‐negative bacteria. Sensitive cells, following treatment with pediocin AcH, lost intracellular K ions, u.v.‐absorbing materials, became more permeable to ONPG and, in some strains, lysed. Binding of pediocin AcH was maximum at pH 6.0. Anions of several salts inhibited binding of pediocin AcH but this was overcome by increased concentrations of pediocin AcH. Treatment of sensitive cells with 1% SDS, 4 mol/1 guanidine‐HCl, several organic solvents and enzymes did not reduce subsequent binding of pediocin AcH. Partially purified cell wall from a sensitive strain was also able to bind pediocin AcH. However, treatment of the cell walls to remove lipoteichoic acid prevented binding. These molecules might, therefore, be one of the binding sites of pedio

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1991.tb03782.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Stems of cut rose flowers (Rosa hybridaL. cv. ‘Sonia’) were placed in water to study the development of a population of micro‐organisms at the cut surface and in the xylem vessels. The cut surface became covered with bacteria within 2 d of vase life. The bacteria were accompanied by an amorphous substance which was apparently bacterial slime. After 7 d of vase life many fungal hyphae were also found at the cut surface. Inside the xylem vessels the bacteria were often clustered at the inter‐vessel pits. After 4 d of vase life most of the vessels that had been opened by cutting contained bacteria. Only a few xylem elements, located several centimeters from the cut surface, contained an amorphous substance. A few fungal hyphae were observed inside the xylem vessels. No yeasts were found, either at the cut surface or inside the xylem.Pseudomonasspecies accounted for more than 70% of the total bacterial population of the cut surface and the xylem vessels, andEnterobacterspecies (mainlyEnt. agglomerans) for less than 10%.Acinetobacter, Aeromonas, Alcaligenes, Bacillus, CitrobacterandFlavobacteriumwere occasionally o

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1991.tb03783.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Portions of skinless chicken breast meat (pH 5·8) were inoculated with a strain ofListeria monocytogenesand stored at 1, 6 or 15°C in (1) aerobic conditions; (2) 30% CO2+ air; (3) 30% CO2+ N2; and (4) 100% CO2. When samples were held at 1°C the organism failed to grow under any of the test conditions, despite marked differences between treatments in spoilage rate and ultimate microflora. At 6°C counts ofL. monocytogenesincreasedca10‐fold in aerobic conditions before spoilage of the meat, but only when the inoculum culture was incubated at 1°C rather than 37°C. In CO2atmospheres growth ofL. monocytogeneswas inhibited on meat held at 6°C, especially under 100% CO2. By contrast, storage at 15°C led to spoilage of the meat within 2 d, in all gaseous environments, and listeria levels increased up to 100‐fold. Differences in the behaviour ofL. monocytogeneson poultry and red meats ar

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1991.tb03784.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

L‐forms ofBacillus breviswere induced and maintained in L‐phase medium supplemented with inactivated horse serum with a combination of penicillin (80 u/ml) and cephalosporin (5 μg/ml) in liquid medium and penicillin (200 u/ml) in diphasic culture. These L‐forms failed to grow on solid

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1991.tb03785.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Clostridium pasteurianumfermented glucose to acetate, butyrate, CO2and H2. In batch cultures the fermentation pattern was only slightly affected by culture pH over the range 8·0 to 5·5. The acetate/butyrate ratio was always higher than or equal to one. Between 2·14 and 2·33 mol H2was produced per mol glucose fermented. At unregulated pH, more butanol and less butyrate was formed. In a carbon‐limited chemostat, the steady‐state acetate/butyrate ratio was always lower than one. H2production was approximately 1·70 mol per mol glucose consumed. Substantial amounts of extracellular protein were formed. With decreasing pH, acetate and formate production decreased, while H2production was highest at pH 6.0. With increasing dilution rate (D), the product spectrum hardly changed, but more biomass was formed.YglucosemaxandYATPmaxwere 55·97 and 31·48 g dry weight per mol glucose or ATP respectively. With increasing glucose input the formation of fatty acids and H2slightly decreased.Continuous cultures fermented mannitol to acetate, butyrate, butanol, CO2and H2. With acetate as co‐substrate, butanol production and molar growth yields,YmannitolandYATP, markedly decreased, while the butyrate and H2production increased. The latter reached a value of 2·21 mol H2per mol mann

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1991.tb03786.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Induction of acid resistance (habituation) inEscherichia coliat pH 5·0 tookca5 min in broth at 37°C and 30–60 min in minimal medium. Induction occurred at a range of pH values from 4·0 to 6·0; it was dependent on continuing protein and RNA synthesis but substantial acid resistance appeared in the presence of nalidixic acid. Acid resistance was long‐lasting; organisms grown at pH 5·0 retained most of their resistance after 2 h growth at pH 7·0. Organisms grown at pH 5·0 showed increased synthesis of a number of cytoplasmic proteins compared with the level in cells grown at pH 7·0. DNA repair‐deficient strains carryingrecA, uvrAorpolAlmutations were more acid‐sensitive than the repair‐proficient parents but were able to habituate at pH 5·0. Organisms grown at pH 5·0 transferred the ColV plasmid much more effectively at acid pH than did those grown at pH 7·0 and habituated recipients appeared better able to repair incoming acid‐damaged plasmid DNA than did those that were non‐habituated. Induction of acid resistance at pH 5·0 may be significant for the survival of organisms exposed to periodic discharges of acid effluent in the aquatic environment and habituation may also allow plasmid transfer and repair of acid‐damaged plasmid DNA du

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1991.tb03787.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY