title: In vitro susceptibility of Prototheca to pH and salt concentration.
abstract: Prototheca sp. can assume high economic significance in the dairy industry and pose a potential risk for the public health. We investigated the in vitro susceptibility of Prototheca isolates retrieved from mastitic milk (P. zopfii and P. blaschkeae) to different pH buffers and salt concentrations using a microbroth assay adapted from the Clinical Laboratory Standards Institute guidelines. Different pH buffer solutions ranging from pH 1 to pH 12 and different sodium chloride concentrations, 4.5, 9 and 18%, were tested. P. zopfii strains presented an optimal growth between pH 5 and 9, a complete growth inhibition at pH 3, and limited growth at pH 1 and 12, whereas P. blaschkeae strains showed higher susceptibility to all pH values except for pH 3 where it demonstrated a moderate growth when compared to P. zopfii strains. When salinity was incremented, P. blaschkeae was more resistant than P. zopfii, although a reduction in growth for all strains of Prototheca was observed. This study demonstrated differences in the in vitro susceptibilities of P. zopfii and P. blaschkeae to different pH and salt concentrations and intend to be a contribution on the understanding of some of the physiologic features that can be associated with the survival of these microalgae in the environment.
authors.affiliation: Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto, Largo Prof. Abel Salazar, 2, 4099-003, Porto, Portugal.
authors.forename: Sara
authors.initials: S
authors.lastname: Marques
authors.forename: Eliane
authors.initials: E
authors.lastname: Silva
authors.forename: Júlio
authors.initials: J
authors.lastname: Carvalheira
authors.forename: Gertrude
authors.initials: G
authors.lastname: Thompson
mesh_terms: D000818:Animals; D000981:Antiprotozoal Agents / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D008892:Milk / Q000469:parasitology; D011525:Prototheca / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D012965:Sodium Chloride / Q000494:pharmacology*
chemical_list: D000981:Antiprotozoal Agents; D012965:Sodium Chloride