Annals of Microbiology, 51, 95-105 (2001) Molecular and physiological analysis of mesophilic aerobic heterotrophic bacteria from the gut of two species of the genus Phaleria Latreille, 1802 (Coleoptera, Tenebrionidae) C. BARBERIO 1* , F. DI CELLO 1 , L. CHELAZZI 2 , I. COLOMBINI 1 , M. FALLACI 1 , R. FANI 1 1 Dipartimento di Biologia Animale e Genetica “Leo Pardi”, Università di Firenze; 2 Centro di Studio per la Faunistica ed Ecologia Tropicali del C. N. R., Via Romana 17, 50125 Firenze, Italy Abstract - Biodiversity of culturable aerobic bacteria from the gut flora of Phaleria provincialis and Phaleria bimaculata, tenebrionid species sympatric on the Burano sandy beach (Italy) was studied by molecular and physiological methods. Results from Amplified Ribosomal DNA Restriction Analysis and Random Amplified Polymorphic DNA as well as those obtained by antibiotic resistance and API 20E test showed the presence of variability at different levels. Diversity was higher among isolates from P. bimaculata. 16S rDNA sequencing enabled us to assign representatives of the three main bacterial clusters to the Citrobacter and Hafnia genera, and to the Yersinia group. Key words: gut bacteria, Phaleria, Tenebrionidae, ARDRA, RAPD. INTRODUCTION Beach arthropods are known to be very important in the food chains of sand beach ecosystems as they represent, together with the microbial and meiofauna, the primary consumers of the organic material of different origin (Brown and McLachlan, 1990; McLachlan, 1991). The coleopteran tenebrionids, the main group of scavengers, are represented in beaches of the entire world by the sub- family of the Phalerinae and the genus Phaleria Latreille is cosmopolitan (Triple- horn, 1991). Not much work has been done on the microbial flora associated to the gut of arthropods (Crowford and Taylor, 1984; Cazemier et al., 1997) and to this date there are no studies concerning the microbial flora associated to the gut of tenebrionids. 95 * Corresponding author. Phone: +39-0552288246; Fax: +39-055222565/ 2288250; e-mail: cbarberio@dbag.unifi.it