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           10                                                                            Ann Microbiol (2015) 65:1–13

                            Bacillaceae genus distribution             Alteromonadaceae genus distribution
                    1.00                                        1.00

                    0.75                                        0.75
                                                  Genus
                                                   Bacillus                                    Genus
                   Percentage  0.50                Pontibacillus  Percentage  0.50               Marinobacter
                                                   Virgibacillus
                                                                                                 Other
                                                   Halobacillus
                                                   Halothiobacillus
                                                   Other
                    0.25                                        0.25
                    0.00                                        0.00
                         shore−line  mid−line  upper−line            shore−line  mid−line  upper−line

                           Rhodobacteraceae genus distribution        Erythrobacteraceae genus distribution
                    1.00                                        1.00
                                                   Genus
                                                     Rhodovulum
                    0.75                             Ahrensia   0.75
                                                     Ruegeria                                Genus
                   Percentage  0.50                  Salipiger  Percentage  0.50              Erythrobacter
                                                     Oceanicola
                                                     Roseovarius
                                                                                              Altererythrobacter
                                                     Maribius
                                                     Loktanella                               Other
                    0.25                             Shimia     0.25
                                                     Sulfitobacter
                                                     Other
                    0.00                                        0.00
                         shore−line  mid−line  upper−line            shore−line  mid−line  upper−line
                                              Ectothiorhodospiraceae genus distribution
                                        1.00

                                        0.75
                                                                       Genus
                                        Percentage  0.50                Thioalkalivibrio
                                                                        Alkalispirillum
                                                                        Alkalilimnicola
                                                                        Thiohalospira
                                                                        Other
                                        0.25
                                        0.00
                                              shore−line  mid−line  upper−line
           Fig. 5 Composition of genera of the main families of Alphaproteobacteria and Bacillales. The relative proportion of genera for Bacillaceae,
           Alteromonadaceae, Rhodobacteraceae, Erythrobacteraceae,and Ectothiorhodospiraceae is reported


           water (Zweifel and Hagstrom 1995). Moreover, a high bacterial  Y-axis. In particular, locations showed different organic car-
           diversity was also found, suggesting that bacterial communities  bon content (see Table 1), which could be related to the
           could have active roles in biogeochemical cycling on a sandy  differences observed between communities. However, no re-
           beach ecosystem. The detected biodiversity is mainly ascribed to  lationships between organic carbon percentage and ribotype
           Proteobacteria, Actinobacteria and Bacteroidetes phyla and to  richness was observed.
           the orders of Flavobacteriales, Actynomicetales, Rhizobiales,  For what is of concern for the differentiation of communi-
           Rhodobacterales, Bacillales, Alteromonadales, Chromatiales,  ties along the Y-axis, the metagenetic analysis of Faraglioni
           and Oceanospirillales. Within these groups, several well known  beach showed a decreasing beta diversity and an increasing
           marine taxa (Rusch et al. 2007) can be found (e.g., in  richness (alpha diversity) along the sea-to-land axis, suggest-
           Oceanospirillales, Chromatiales and Rhodobacterales), suggest-  ing a tendency i) for a lower differentiation when proceeding
           ing that a consistent part of sandy beaches microbiota is of  along the axis (may be due to more homogeneous environ-
           marine origin.                                     mental parameters), and ii) for an increasing number of taxa
             Moreover, by comparing bacterial community fingerprint-  (may be linked to proximity with soil). Among the identified
           ing (T-RFLP profiles) of sandy beaches of three different  bacterial groups with differences of abundance along the axis,
           localities we have shown a considerable heterogeneity of  two main bacterial phyla have opposite trends of abundance
           samples, either due to location and to the position along the  along the Y-axis: Firmicutes and Proteobacteria. Within
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