A Gram-negative, dark orange-pigmented, aerobic, non-spore-forming, coccoid-shaped bacterium designated as ZS-1/3T was isolated from a floating plastic litter (polypropylene straw) sample, collected from shallow seawater near the public beach of Laganas on Zakynthos island, Greece. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolate is affiliated with the genus Parvularcula in the family Parvularculaceae. Its closest relatives are Parvularcula lutaonensis (98.09 %) and Parvularcula oceanus (95.89 %). The pH and temperature ranges for growth are pH 5-10 and 20-38 °C (optima, pH 7.0 and 28 °C). The predominant fatty acids are C18 : 1 ω7c (56.84 %), C16 : 0 (27.51 %), C18 : 0 (2.25 %) and C12 : 0 (1.42 %). The predominant respiratory quinone detected in strain ZS-1/3T is quinone-10 (Q10); the majority of detected polar lipids are glycolipid. The DNA G+C content is 62.5 mol%. Physiological and chemotaxonomic data further confirmed the distinctiveness of strain ZS-1/3T from other members of the genus Parvularcula. Thus, strain ZS-1/3T is considered to represent a novel species of the genus, for which the name Parvularcula mediterranea. sp. nov. is proposed. The type strain is ZS-1/3T (=NCAIM B 02654T=CCM 9032T).
Keywords: Greece; Laganas beach; Parvularcula; plastic debris; plastisphere.