FEMS Microbiology Letters 56 (1988) 301-306 301 Published by Elsevier FEM 03385 Adsorption capability determines phage plaque size on Streptomyces antibioticus producing endodeoxyribonuclease Clara G. de los Reyes-Gavilfin, Jesfis F. Aparicio, Covadonga Barb6s, Carlos Hardisson and Jesfis Shnchez Department of Microbiology, Faculty of Medicine, University of Oviedo, Oviedo, Spain Received 26 May 1988 Revision received 12 August 1988 Accepted 18 August 1988 Key words: Phage adsorption; Adsorption; Streptomyces antibioticus; Endodeoxyribonuclease 1. SUMMARY Differences in plaque size of phages developing in Streptomyces antibioticus on several media were mainly determined by their adsorption ability to mycelium obtained at different stages of the bacterial growth-curve. This is due to the exposure of phages to the exocytoplasmic endode- oxyribonuclease produced by this bacterium at the middle-end of the exponential phase. 2. INTRODUCTION At least 14 different restriction-modification systems (R-M) have been detected in Streptomyces [1-6], although only in a few cases has a type II specific endonuclease been unequivocally related with the corresponding biological restriction [7-10]. Characterization of R-M systems in Streptomyces can be hindered by additional fac- Correspondence to: Jesfis Shnchez, Department of Microbi- ology, Faculty of Medicine, University of Oviedo, 33006, Oviedo, Spain. tors [4] such as lack of suitable biological indica- tors (phages or plasmids); existence of phage ad- sorption barriers (often not considered when R-M systems are studied) together with the absence of developed transfection systems in the strain • ~ . . . stud~ed which would otherwise elln'anate such ad- sorption impediments; and the presence of 'unor- thodox' restriction activities in the strains consid- ered, not associated with corresponding modifica- tion systems [11; see below]. In vitro sensitivity of phage DNA to the host- specific restriction enzymes has been proposed to be the major determinant for broad host-range bacteriophage specificity in Streptomyces [1]. In this way, one simple mechanism for a phage to avoid host restriction would be the absence in its DNA of the target sites for the particular Streptomyces endonuclease [12] through a selective pressure against these sites. However, this view can be more complex as recent studies have shown that in some cases additional host-specific activi- ties can influence phage development. In S. anti- bioticus ATCC 11891 and S. glaucescens ETHZ 22794 an endodeoxyribonuclease activity, located in the cell wall-membrane region has been re- ported to affect phage plaque size and even to 0378-1097/88/$03.50 © 1988 Federation of European Microbiological Societies Downloaded from https://academic.oup.com/femsle/article-abstract/56/3/301/483900 by guest on 02 June 2020