engleski

DIVERSITY OF EPIPHYTIC BACTERIAL COMMUNITIES FOUND ON NORTHERN ADRIATIC FUCACEN SPECIES

The surface of brown macroalgae is colonized by epiphytic bacteria which are characterized by abilities of fast colonization, quick metabolic response to algal exudates, and adaptation to environmental variations. Epiphytic bacteria found on Fucales differ significantly from bacterial communities found on surrounding abiotic surfaces [1, 2]. In addition to the fucacean ecology and the vegetative cycling that significantly influence species resilience to the climate and anthropogenic stress, positive species interactions in the phycosphere can act as a first defense barrier against abiotic stress [3]. The study aimed to determine epiphytic bacterial communities of selected fucacean species (Treptacanta barbata, Carpdesmia crinita, and Cystoseira compressa) and to explore the relationship between the fatty acid profiles of selected fucacean species and their associated epiphytic bacterial communities. The thalli of sampled species were divided into perennial and annual parts. T. barbata and C. crinita show high contents of mono- and polyunsaturated fatty acids. The branches and apical parts of C. crinita demonstrated high proportion of both C18 and C20 polyunsaturated fatty acids but also, C. crinita showed the highest unsaturation degree (4.32%) in opposition to the highest proportion of saturated fatty acids which was found in thalli of C. compressa. Several representatives of the Gammaproteobacteria class, identified as Vibrionales, Cellvibrionales, and Xanthomonadales were found which contributed strongly to the separation of T. barbata apical parts and branches, C. compressa receptacles and C. crinita branches from the T. barbata cauloids and C. crinita apical parts and cauloids. The results showed a strong relationship between fatty acid profiles of the analyzed species and phycosphere community structure, underlining the host physiological condition in shaping the biological interactions and maintaining a healthy microbiome.

brown macroalgae ; bacterial communities ; phycosphere ; fatty acids

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