Preliminary data on the occurrence and genotyping of Prototheca zopfii, a cause of bovine mastitis in dairy cattle farms in Veneto region Danesi P.1,2, Biasion L.1, Cristofoli C.1, Mazzacan E.1, Frangipane di Regalbono A.3, Capelli G.1 1Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro (PD), Italy; 2Department of Public Animal Health, Bari University, Italy; 3Department of Animal Medicine, Production and Health, Padua University, Italy ; Introduction: Bovine mastitis due to unicellular, achlorophyllous algae of the genus Prototheca has been almost exclusively associated with only one species Prototheca zopfii. Recently, based on the 18S rDNA sequence analysis, P. zopfii has been divided into three genotypes (1–3), of which P. zopfii genotype 3 has been given the status of a new species Prototheca blaschkeae sp. (Roesler U., 2006, International Journal of Systematic and Evolutionary Microbiology 56: 1419–1425) Aims: The aim of this study was to investigate the occurrence and the genotypic composition of the population of P. zopfii bovine mastitis isolated from diary cows farms in Veneto region. Methods: From August 2011, 15 diary farms from Vicenza province grouped in 3 categories were investigated for the presence of Prototheca sp. Groups were described as number of lactating cows: group A (≤ 50), group B (50-100) and group C (≥ 100). Samples examined were: milk from cows with a Total Count Cells (TCC) > 200.000, milk from Bulk-Tank milk, specimens of cow-barn surroundings as bedding and surface swabs from milking machine. All samples were cultivated on Prototheca isolation medium (PIM) at 37°C from three to five days. Identification at level species were riched by morphological methods and genotype discrimination by extraction and sequencing of 18S rDNA amplicons. Nucleotide BLAST of the sequences obtained were aligned in the Genebank database Results: Overall 4 (26.7%) of the 15 diary farms were positive for Prototheca sp. In particular Prototheca grew from cultures of individual milk (n=3), composite milk (n=4) and swabs (n=7) from group A and B, while in group C the occurrence of algae was only from the bedding (n=1). Prototheca zopfii gen 2 was isolated from all type of samples but not from bedding while Prototheca blaschkeae on the contrary was isolated from bedding and composite milk but not from individual milk. Prototheca zopfii gen.2 Conclusions: These preliminary data suggest that bovine mastitis due to Prototheca species are more common than reported by literature. In particular this study confirms the possible role of P. zopfii genotype 2 as the main mastitis pathogen and support the hypothesis of other Authors (Ricchi M. et al,2010, J Dairy Sci, 93(10):4625-4631) that such pathology could be caused occasionally by P. blaschkeae. Our next goal will be focus on the study of prototheca prevalence in the positive farms to try to better understand the transmition ways of the pathogens in the environment to prevent animals from sources of infections. Prototheca has poor sensitivity to the conventional antibiotics and antifungal treatments,Rakesh R.et al. (CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources 2006 1, No. 017). so preventive measures are the best way for controlling the disease. XXVII Congresso SoIPa – 26-29 Giugno 2012 – Alghero (SS) – Italy This work was supported by Italian Ministry of Health (project code RC IZSVe 05/09)