ORIGINAL PAPER Temperature preferences of bacteria isolated from seawater collected in Kandalaksha Bay, White Sea, Russia Chiara Pesciaroli • Francesco Cupini • Laura Selbmann • Paolo Barghini • Massimiliano Fenice Received: 4 April 2011 / Revised: 28 July 2011 / Accepted: 16 August 2011 / Published online: 10 September 2011 Ó Springer-Verlag 2011 Abstract Fifty-two bacteria were isolated from seawater collected in Kandalaksha Bay, White Sea, Russia, and classified by 16S rDNA sequencing. Most of the strains belonged to ubiquitous microorganisms. Pseudomonas was the most abundant genus (21 strains), including species of P. fluorescens, P. putida and P. syringae. Serratia was also common (10 strains) with species S. plymuthica and S. proteamaculans. Sphingobacterium, Flavobacterium and Pantoea were less represented (5, 3 and 2 strains, respec- tively). The only typical bacterium of marine Arctic regions was Shewanella baltica. The strains were tested for their optimal growth temperature in the range 0–45°C. The majority appeared to be psychrotolerant (42%) or meso- philic-psychrotolerant (40%). In addition, one strain (Bacillus pumilus) showed a rather narrow mesophilic profile. No true psychrophilic bacteria were found. Most of the strains showed a classical curve with fast growth decrease above the optimum; some others displayed uncommon flat curves with scarce differences between maximum and minimum of growth in a wide range of temperatures. Moreover, few strains presented an unusual profile being, in relation to the optimum, more tolerant to high rather than low temperatures. Preferences of the Kandalaksha Bay strains are generally different from those reported in literature for the same species: optima were at lower temperatures and, sometimes, ranges were broader showing increased eurythermism. This could indicate adaptation to the wide temperature variations recorded in this peculiar environment. Keywords Temperature preferences Á Bacterial strains Á Sub-extreme environment Á Kandalaksha Bay Á White Sea Introduction Seas and oceans represent a pool of extremely interesting environments for ecological and biotechnological studies. So far, much of the attention, for this kind of investiga- tions, had been focused on other microbial ecosystems. Thus, marine environments, in particular those presenting extreme conditions, remain largely unstudied and unex- ploited (Rothschild and Mancinelli 2001; Bai et al. 2006; Srinivas et al. 2009). White Sea is an enclosed basin, located at the Arctic Circle, that can be considered as a sub-extreme environ- ment (Pantyulin 2003). Kandalaksha Bay is an estuarine system showing big sea level differences during tide cycles causing strong mixing of water (Melnikov et al. 2003; Savvichev et al. 2003). In addition, the seasonal extremes runoff of freshwater, due to the various rivers and intense precipitations, contributes to its very peculiar hydrody- namics (Howland et al. 1999; Dolotov et al. 2005). The coastal zone influenced by the tides (intertidal zone or littoral) is particularly interesting because all biogeo- chemical processes are most evident. This is especially true if tidal phenomena are very pronounced as in Kandalaksha Bay. Organisms in this zone need adaptation to variable environmental conditions in which factors, such as water availability, temperature and salinity, change frequently (Savvichev et al. 2004). C. Pesciaroli Á F. Cupini Á L. Selbmann Á P. Barghini Á M. Fenice DEB, Dipartimento di Scienze Ecologiche e Biologiche, University of Tuscia, Largo Universita ` snc, 01100 Viterbo, Italy M. Fenice (&) Laboratory of Applied Marine Microbiology (Conisma), University of Tuscia, Largo Universita ` snc, 01100 Viterbo, Italy e-mail: fenice@unitus.it 123 Polar Biol (2012) 35:435–445 DOI 10.1007/s00300-011-1091-1