摘要:

Twenty-four urogenital isolates of coagulase-negative staphylococci were selected because of their demonstrated ability to inhibitNeisseria gonorrhoeaegrowthin vitro. These organisms showed quantitative differences in their growth-interfering capability as revealed by a flip-flop agar overlay method. The composition of the culture medium affected the production of antigonococcal activity. Antigonococcal activity was shown with the following media: GC agar base with Lankford defined supplement, brain heart infusion agar, trypticase soy agar, and dextrose starch agar, but not with the GC agar base with CVA enrichment. An antigonococcal activity was obtained in the liquid phase prepared from semisolid agar cultures for 10 of the 24 staphylococcal isolates, whereas no activity was found in the supernatant from liquid cultures. The production of antigonococcal activity by staphylococciin vitrois influenced by growth conditions.

ISSN:0008-4166    

DOI:10.1139/m81-021

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The production of chitinase bySerratia marcescensQMB1466 was studied in continuous culture withN-acetylglucosamine as limiting substrate. Enzyme activity in the culture filtrate exhibited a maximum with respect to dilution rate, a phenomenon that can be explained as a balance between induction and catabolite repression.

ISSN:0008-4166    

DOI:10.1139/m81-022

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Certain norcarotenoids, which have recently been found as excretion products of freshwater cyanobacteria and algae, are potent inhibitors of different metabolic functions in heterotrophic bacteria. 6-Methylhept-5-en-2-one showed the strongest effects and acted as a noncompetitive inhibitor of both glucose uptake and respiration by aquatic isolates ofChromobacterium lividumandArthrobactersp. Inhibition of the heterotrophic potential of glucose uptake by 6-methylhept-5-en-2-one was characterized by considerably lower inhibitor constants for bacterial cultures (Ki = 0.4 and 1.6 μM) than for a river water sample (Ki = 186.0 μM).

ISSN:0008-4166    

DOI:10.1139/m81-023

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Comparison of the Anderson–Baird-Parker direct plating method (DP) and the North American most probable number procedure (MPN) for enumeratingEscherichia coliin frozen meats revealed that the DP method is more precise and yields higher counts ofE.colithan the MPN procedure. Any of three brands of membrane filters tested was suitable for use in the DP method.

ISSN:0008-4166    

DOI:10.1139/m81-024

出版商:NRC Research Press    

年代:1981

数据来源: NRC