摘要:

The effect of the addition of chloramphenicol and various salts on growth and acid production ofLactobacillus helveticusstrain milano has been investigated using lactose medium. Injection of chloramphenicol induced uncoupling of growth and acid production. Addition of high salt concentrations also resulted in growth inhibition whereas product formation continued. NaCl and CaCl2were more inhibitory to the growth ofLact. helveticusstrain milano than KCl.

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1991.tb00541.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The content of aflatoxin and associated fungi was determined in 56 samples, including 34 of corn, 10 of soybean meal, nine of rice bran and three of broken rice, collected from different poultry farms and poultry feedmills situated around Jakarta‐Bogor, Indonesia.Ninety‐one per cent of the corn samples contained aflatoxins and the total concentration ranged from 22 to 6171μg/kg. With rice bran, 100% of the samples were positive for aflatoxin B1, ranging from 36 to 71μg/kg. No aflatoxin was detected in samples of soybean meal or broken rice. All the samples were contaminated by several fungi (8 times 103–5 times 106cfu/g) and further identification was limited toAspergillus flavusandA. parasiticus.The dominant species wasA. flavus(2 times 103–4 times 106cfu/g in corn samples, 1·0 times 103–1·0 times 105cfu/g in soybean meal, 2 times 104–4·4 times 105cfu/g in rice bran and 2 times 104–6 times 104cfu/g in broken rice). Some of the corn samples also containedA. parasiticus(2 times 103

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1991.tb00542.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

3,5‐Xylenol degradative plasmid, pRA500 (approximately 500 kilobase pairs, kb) carried byPseudomonas putidaNCIB 9869, also encodes resistance to inorganic mercuric ions (Hgr). Following growth ofPs. putidaon benzoate,p‐cresol,p‐hydroxybenzoate or protocatechuate, the frequency of loss of the 3,5‐xylenol phenotype was 75–90%. The deletion of a large segment of approximately 350 kb from pRA500, to give rise to archetypal plasmid designated pRA502, occurred in such 3,5‐xylenol‐negative derivatives. During the conjugational transfer of pRA500 following selection of transconjugants for Hgronly, frequency of loss of 3,5‐xylenol phenotype was approximately 60%. A high number of these 3,5‐xylenol‐negative transconjugants carried pRA502. A site‐specific deletion is suggested in the formation of archetypal plasmid pRA502 by growth ofPs. putidaon the above compounds and duri

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1991.tb00543.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The rate of fermentation of glucose by a polyploid strain ofSaccharomyces cerevisiaegrowing in a defined salts medium depends on the availability of NH4++. Its decline after exhaustion of the nitrogen source corresponded with the ability of the cells to accumulate the glucose analogue 2‐deoxyglucose. Addition of NH4++to a nitrogen‐depleted culture stimulated both glucose utilization and 2‐deoxyglucose uptake. Since stimulation was inhibited by cycloheximide, maintenance of glucose transport during fermentation is dependent on protein synt

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1991.tb00544.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

A simple, sensitive, dried gel DNA hybridization method for detection ofListeria monocytogenesDNA fragments is described. DNA samples were fractionated on an agarose gel. The gel was then denatured in NaOH‐NaCl and neutralized in Tris‐NaCl. The resulting agarose gel was dried and hybridized with32P‐labelled DNA probe. No transfer to nitrocellullose membranes was

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1991.tb00545.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Thirty strains ofLactobacillus gasseriisolated from infant faeces were examined for production of an antimicrobial agent against 10 strains of the seven species of the genusLactobacillus.Each of the strains inhibited the growth of at least one of the indicator strains. The agent was sensitive to proteolytic enzymes and stable for 20 min at 120°C. It is a bacteriocin designated as gassericin A

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1991.tb00546.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The effect of fibrolytic and saccharolytic rumen bacteria on xylanolysis by the rumen fungusNeocallimastix frontalishas been investigated. In cocultivationsN. frontalisinteracted synergistically withBacteroides ruminicola, Succinivibrio dextrin‐osolvensandSelenomonas ruminantiumduring xylan utilization. Xylan utilization decreased in cocultures containingLachnospira multiparusorStreptococcus bovis. Ruminococcus flavefaciensappeared to inhibit fungal growt

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1991.tb00547.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Electron particle sizing (Coulter counter) was used to measure cell and protoplast volumes ofSaccharomyces cerevisiaegrown under different conditions designed to increase its cryotolerance. Membrane water permeabilities were estimated from those measurements. A relationship was obtained between the lower water permeability of yeast grown under microaerobic batch conditions and its weaker cryotolerance in water (cooling rate of 39·6°C/min), as compared to fed‐batch cells. For the latter, cell water permeability was not related to the observed differences in survival for frozen‐thawed cells grown under strong or partial (with temporary limitation of dissolved oxygen in growth media) aerobic condi

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1991.tb00548.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Salt whey was examined as a substrate for lactic acid production byLactobacillus caseiin conventional and immobilized cell batch systems. In cell suspension systems this strain was not able to metabolize lactose in the presence of salt concentrations much above 4%. However, the entrapment of cells in 2% agar substantially improved their activity and allowed slow metabolism even in the presence of 8% salt. The agar matrix retained its structure and dimensional stability during 168 h in salt medium.

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1991.tb00549.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Alginate‐producingPseudomonas aeruginosa8821 spontaneously produced low‐ and high‐alginate‐producing variants that had low and high specific activities of GDP‐mannose dehydrogenase and high and low specific growth rates, respectively. The optimal temperature for alginate production was 10°C below that for growth in the case of the high‐producer but they were the same for the low‐producer. In short duration thermal death experiments, alginate protected cells against lethal temperatures, although the maximal temperature for growth of the mucoid variants (43°C) was lower than that for the non‐mucoid strain (44°C). The temperature profiles were associative and above 37°C growth concurred

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1991.tb00550.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY