FEMS Microbiology. Ecology 10l (1992)33-39 '~:; 1992 Federation of European Microbiological Societies 0168-6496/92/51)5.110 Published by Elsevier 33 FEMSEC 00387 Temperature effects on the viable but non-culturable state of Vibrio vulnificus Paula W. Wolf and James D. Olivcr Department of BioloD', Unirersia." of North Carolina at Charlone. Charlone. NC. USA Received 18 August 1991 Revision received 9_5 February. 1992 Accepted 27 February 1992 Key words: Vibrio; Marine bacteria; Public health 1. SUMMARY The non-cuiturable state of Vibrio culnificus, strain C7184, was studied in artificial seawater microcosms held at 5, 10, 15, 20, and 30°C. Plate counts were made on a non-selective medium, total cell counts were monitored by acridine or- ange epilluorescence, and direct viable counts (DVCs) by the method of Kogure et ai. (Can J. Microbiol. 25, 415-420; 1986) and by th? INT method. From an initial inoculum of 107 cells/ml, V. rulnificus became non-culturable within 40 days at 5°C, although both indicators of viability re- vealed a viable population exceeding 10" cells/ml. Cells at all higher temperatures remained cuitur- able (at least 104/mi) throughout the study. The non-culturable states of the opaque and translu- cent colony variants of 1,: cuhuficus, as well as those of six other clinical and environmental strains of V. culni~cus, were examined at 5°C; all Correspondence to: J.D. Oliver. Department of Biology, Uni- versity of North Carolina at Charlotte. Charlotte, NC 28223. USA. but one strain and both colony variants also be- came non-culturable within 40 days. In contrast, six other Vibrio spp. (V. cholerae, V. mbnicus, V. parahaemolyticus, V. natriegens, V. proteolyticus, and V. campbelli) remained culturable at 5°C. Thus, entrance of V. culnificus into the non- coiturable state appears to be highly temperature dependent and. among the vibrios, this species may be especially sensitive to low temperature. The public health aspects of the~c 5,dings are discussed. 2. iNTRODUCTION Vibrio ,'ulnificus is an estuarine bacterium re- sponsible for potentially fatal infections, espe- cially in persons with elevated serum-iron levels or immunosuppresive disorders. Most infections are reported during warm months, and although wound infections frequently occur, the most seri- ous and common route of infection is ingestion of raw oysters [1]. The seasonality of infections cor- responds to the ability to readily isolate V. cuinifi- cus from w.a.~cr, sediment, and oyster samples Downloaded from https://academic.oup.com/femsle/article-abstract/101/1/33/515812 by guest on 30 May 2020