Eur Food Res Technol (2008) 226:1065–1073 DOI 10.1007/s00217-007-0632-x 123 ORIGINAL PAPER Adhesion and aggregation properties of probiotic and pathogen strains Maria Carmen Collado · Jussi Meriluoto · Seppo Salminen Received: 9 January 2007 / Revised: 9 March 2007 / Accepted: 21 March 2007 / Published online: 12 April 2007  Springer-Verlag 2007 Abstract Autoaggregation has been correlated with adhe- sion, which is known to be a prerequisite for colonization and infection of the gastrointestinal tract by many patho- gens. The coaggregation properties of probiotic strains with pathogens as well as their ability to displace pathogens are of importance for therapeutic manipulation of the aberrant intestinal microbiota. Consequently, the ability to aggregate and coaggregate are desirable properties for probiotics in health-promoting foods. Aggregation assays and bacterial adhesion to hydrocarbons (BATH test) demonstrated sig- niWcant diVerences in cell surface properties among the tested commercial probiotic strains. Hydrophobicity increased when the cells were heat-inactivated. All probiotic strains tested showed aggregation abilities with the pathogen strains tested, but the results were strain-speciWc and depen- dent on time and incubation conditions. Our results indicate that the ability to autoaggregate, together with cell-surface hydrophobicity and coaggregation abilities with pathogen strains can be used for preliminary screening in order to identify potentially probiotic bacteria suitable for human or animal use. Keywords Adhesion · Probiotics · Pathogens · Aggregation Introduction The human intestinal microbiota constitutes a complex eco- system that plays an important role in healthy and diseased conditions in which various pathogens alter the intestinal bacterial homeostasis. There are also food bacteria, which exhibit speciWc beneWcial properties through microbiota modulation, probiotics. The protective role of probiotic bacteria against gastrointestinal pathogens and the underly- ing mechanisms has received special attention. Pathogen inhibition by lactic acid bacteria might provide signiWcant human health protection against pathogen infection either as a natural barrier against pathogen exposure in the gastro- intestinal tract or as a method to decontaminate drinking water or food. This would enhance human health and have a positive economic impact especially in developing coun- tries the people of which suVer from frequent gastrointesti- nal infections. SpeciWc strains of Lactobacillus, BiWdobacterium and also some Propionibacterium strains have been introduced as probiotics in food products due to their health-promoting eVects. A probiotic has been deWned as a “live microorgan- ism which when administered in adequate amounts confers a health beneWt on the host” [1]. Criteria for selection of probiotics include lack of pathogenicity, tolerance to gas- trointestinal conditions (acid and bile), ability to adhere to the gastrointestinal mucosa and competitive exclusion of pathogens [2, 3]. The most extensive studies and clinical applications of probiotics have been related to the manage- ment of gastrointestinal infections caused by pathogenic microorganisms. The development of adjuvant or alterna- tive therapies based on bacterial replacement is considered important due to the rapid emergence of antibiotic-resistant pathogenic strains and the adverse consequences of antibi- otic therapies on the protective microbiota [4]. Probiotic M. C. Collado (&) · S. Salminen Functional Foods Forum, University of Turku, Itäinen Pitkäkatu 4 A, 5th Xoor, 20520 Turku, Finland e-mail: marcol@utu.W J. Meriluoto Department of Biochemistry and Pharmacy, Abo Akademi University, Tykistökatu 6A, 20520 Turku, Finland